FOUS30 KWBC 200805
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
405 AM EDT Sat Sep 20 2025

Day 1
Valid 12Z Sat Sep 20 2025 - 12Z Sun Sep 21 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE MIDWEST, THE SOUTHERN PLAINS, OZARKS, AND THE CENTRAL=20
APPALACHIANS...

...Wisconsin and northern Illinois...

A negatively-tilted upper trough will lift slowly across the mid to
upper Mississippi Valley today. The associated ascent interacting
with a ribbon of relatively deeper moisture (PWs 1.25-1.5 inches)=20
along a modest low level jet will support showers and storms=20
redeveloping this afternoon, which may potentially continue into=20
the evening. With differences in the details, the CAMs generally=20
indicate two areas of locally heavier amounts -- a north-south axis
associated with storms lifting across eastern Wisconsin during the afternoon/evening and a west-east stripe produced by storms=20
developing across Iowa and then training across northern Illinois=20
later during the overnight. HREF neighborhood probabilities=20
indicate localized amounts in excess of 2 inches are possible in=20
these areas.

...Ozarks to southwestern Oklahoma....

CAMs indicate that ongoing convection firing north of a stationary
front over southern Kansas will continue through the late morning,
potentially producing heavy amounts as they train further east=20
into the Ozark Region. The HREF shows high neighborhood=20
probabilities for accumulations over 2 inches centered over this=20
region.=20

Then, as upstream energy sliding southeast across the central=20
Plains interacts with deepening moisture that will be supported by
increasing southerly low level flow, some guidance indicate that=20
storms will redevelop over this same area later today. However,=20
other models show storms developing further to the west before=20
moving back into areas impacted by this morning's storms.=20

While there is fair amount of uncertainty on how these storms=20
across central into eastern Oklahoma will evolve, there is greater=20
model consensus that storms developing over the Texas Panhandle and
western Oklahoma by this evening will merge across southwestern=20
Oklahoma to produce locally heavy amounts across the region during
the overnight.=20

...West Virginia...

CAMs continue to show isolated heavy amounts associated with slow-
moving storms that are expected to develop over eastern West=20
Virginia this afternoon. A weak impulse lifting northeast out of=20
the Ohio Valley, interacting with pooling moisture along a slowing
front, will support storm development. HREF neighborhood=20
probabilities indicate that amounts of 2-3 inches are likely within
the highlighted area.

Pereira

Day 2 Valid 12Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL PLAINS, MID MISSISSIPPI VALLEY, AND THE SOUTHWEST...

...Eastern Kansas and northeastern Oklahoma to southern Illinois...

Deepening moisture (PWs above 1.5 inches) along an axis of
strengthening southerly to southwesterly flow ahead an amplifying
upper trough will fuel showers and storms, possibly producing=20
heavy amounts. While models differ significantly on the details,=20
the general consensus indicates widespread precipitation is likely,
with locally heavy amounts of 1-2 inches possible.

...Southwest...

An upper low dropping to the south along the California coast will
slow as it becomes cutoff west of Southern California. Southerly=20
flow ahead of the system will support increasing moisture and the
chances for precipitation across parts of Southern California and=20
Arizona. Both the GFS and ECMWF show PW anomalies increasing to 2.5
to 3 standard deviations above normal across far Southern=20
California through the lower Colorado Basin into Arizona.=20

Pereira

Day 3
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHWEST AND FROM KANSAS AND OKLAHOMA TO THE OHIO VALLEY...

...Kansas and Oklahoma to the Ohio Valley...

Unsettled weather will continue, with the footprint for potentially
heavy rain expanding as energy moving through the base of a broad
upper trough interacts with deep moisture that will be supported=20
persistent southwesterly flow. While models generally agree on a=20
large footprint of moderate to heavy amounts, they lack agreement=20
on the details. At least locally heavy amounts are expected,=20
especially within the western portions of the highlighted area as=20
a well-defined shortwave dives southeast and is expected to=20
interact with a pool of deepening moisture along a strong=20
southwesterly low level jet. Given the indication of 2-3 inches in
some of the models, which is forecast to fall in addition to the=20
previous days' amounts, an upgrade to a Slight Risk may be=20
forthcoming if the signal persists and the guidance moves into=20
better agreement.

...Southwest...

An upper low is forecast to remain cutoff and drift slowly east=20
along the Southern California coast. Anomalous moisture in place=20
across Arizona is expected to spread east into parts of New Mexico,
extending the chances for showers and storms, with potentially=20
heavy amounts into the region.

Pereira


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8pQe_tdoCfnj7adGK831Q_zOMCD5YW0IWloZQV_8pvYM= PtkZSKzaW4kxYXGO2_QGvpZTQ_3u6HWv2H6-15xunQxUopQ$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8pQe_tdoCfnj7adGK831Q_zOMCD5YW0IWloZQV_8pvYM= PtkZSKzaW4kxYXGO2_QGvpZTQ_3u6HWv2H6-15xuKZRskZg$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8pQe_tdoCfnj7adGK831Q_zOMCD5YW0IWloZQV_8pvYM= PtkZSKzaW4kxYXGO2_QGvpZTQ_3u6HWv2H6-15xuyZmrDMg$=20

=3D =3D =3D
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FOUS30 KWBC 200821
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
421 AM EDT Sat Sep 20 2025

Day 1
Valid 12Z Sat Sep 20 2025 - 12Z Sun Sep 21 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE MIDWEST, THE SOUTHERN PLAINS, OZARKS, AND THE CENTRAL
APPALACHIANS...

...Wisconsin and northern Illinois...

A negatively-tilted upper trough will lift slowly across the mid to
upper Mississippi Valley today. The associated ascent interacting
with a ribbon of relatively deeper moisture (PWs 1.25-1.5 inches)
along a modest low level jet will support showers and storms
redeveloping this afternoon, which may potentially continue into
the evening. With differences in the details, the CAMs generally
indicate two areas of locally heavier amounts -- a north-south axis
associated with storms lifting across eastern Wisconsin during the afternoon/evening and a west-east stripe produced by storms
developing across Iowa and then training across northern Illinois
later during the overnight. HREF neighborhood probabilities
indicate localized amounts in excess of 2 inches are possible in
these areas.

...Ozarks to southwestern Oklahoma....

CAMs indicate that ongoing convection firing north of a stationary
front over southern Kansas will continue through the late morning,
potentially producing heavy amounts as they train further east
into the Ozark Region. The HREF shows high neighborhood
probabilities for accumulations over 2 inches centered over this
region.

Then, as upstream energy sliding southeast across the central
Plains interacts with deepening moisture that will be supported by
increasing southerly low level flow, some guidance indicate that
storms will redevelop over this same area later today. However,
other models show storms developing further to the west before
moving back into areas impacted by this morning's storms.

While there is fair amount of uncertainty on how these storms
across central into eastern Oklahoma will evolve, there is greater
model consensus that storms developing over the Texas Panhandle and
western Oklahoma by this evening will merge across southwestern
Oklahoma to produce locally heavy amounts across the region during
the overnight.

...West Virginia...

CAMs continue to show isolated heavy amounts associated with slow-
moving storms that are expected to develop over eastern West
Virginia this afternoon. A weak impulse lifting northeast out of
the Ohio Valley, interacting with pooling moisture along a slowing
front, will support storm development. HREF neighborhood
probabilities indicate that amounts of 2-3 inches are likely within
the highlighted area.

Pereira


Day 2
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL PLAINS, MID MISSISSIPPI VALLEY, AND THE SOUTHWEST...

...Eastern Kansas and northeastern Oklahoma to southern Illinois...

Deepening moisture (PWs above 1.5 inches) along an axis of
strengthening southerly to southwesterly flow ahead an amplifying
upper trough will fuel showers and storms, possibly producing
heavy amounts. While models differ significantly on the details,
the general consensus indicates widespread precipitation is likely,
with locally heavy amounts of 1-2 inches possible.

...Southwest...

An upper low dropping to the south along the California coast will
slow as it becomes cutoff west of Southern California. Southerly
flow ahead of the system will support increasing moisture and the
chances for precipitation across parts of Southern California and
Arizona. Both the GFS and ECMWF show PW anomalies increasing to 2.5
to 3 standard deviations above normal across far Southern
California through the lower Colorado Basin into Arizona.

Pereira


Day 3
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHWEST AND FROM KANSAS AND OKLAHOMA TO THE OHIO VALLEY...

...Kansas and Oklahoma to the Ohio Valley...

Unsettled weather will continue, with the footprint for potentially
heavy rain expanding as energy moving through the base of a broad
upper trough interacts with deep moisture that will be supported
persistent southwesterly flow. While models generally agree on a
large footprint of moderate to heavy amounts, they lack agreement
on the details. At least locally heavy amounts are expected,
especially within the western portions of the highlighted area as
a well-defined shortwave dives southeast and is expected to
interact with a pool of deepening moisture along a strong
southwesterly low level jet. Given the indication of 2-3 inches in
some of the models, which is forecast to fall in addition to the
previous days' amounts, an upgrade to a Slight Risk may be
forthcoming if the signal persists and the guidance moves into
better agreement.

...Southwest...

An upper low is forecast to remain cutoff and drift slowly east
along the Southern California coast. Anomalous moisture in place
across Arizona is expected to spread east into parts of New Mexico,
extending the chances for showers and storms, with potentially
heavy amounts into the region.

Pereira


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8eaviJ_qpft5dZopaMAa1QvUnsZIfTVnJuRpu4zupRPu= uOBqIIfwQJvRBxF6h-0ozvDI5QdJ46NvX6T3IgyQsKm7ydk$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8eaviJ_qpft5dZopaMAa1QvUnsZIfTVnJuRpu4zupRPu= uOBqIIfwQJvRBxF6h-0ozvDI5QdJ46NvX6T3IgyQz6ZFUhk$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8eaviJ_qpft5dZopaMAa1QvUnsZIfTVnJuRpu4zupRPu= uOBqIIfwQJvRBxF6h-0ozvDI5QdJ46NvX6T3IgyQ-sD-HIA$=20

=3D =3D =3D
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FOUS30 KWBC 201557
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1157 AM EDT Sat Sep 20 2025

Day 1
Valid 16Z Sat Sep 20 2025 - 12Z Sun Sep 21 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE MIDWEST, THE SOUTHERN PLAINS AND OZARKS, AND THE CENTRAL=20 APPALACHIANS...

...16Z Update...

Overall, the 3 inherited Marginal Risk areas were only tweaked a
little bit each.=20

...Southern Plains and Ozarks...

An ongoing area of convection near the Moksarok continues to be a
Marginal flooding threat as the storms either linger or reform over
this same area later this afternoon. Most of the Moksarok has seen
about 1-2 inches of rain areally, but with locally higher amounts.
Thus, soils in this small region have become saturated enough that
additional rainfall from stronger storms later this afternoon could
cause isolated instances of flash flooding. Meanwhile, further
southwest, a secondary area of convection that is more aligned with
the core of the low level jet, will likely form very late tonight
across the Texas Panhandle, southwest Oklahoma and far north
Texas. These storms will pose an isolated overnight flash flooding
risk, and should be entirely separate from the storms ongoing near
the Moksarok. Since they will both be along the same boundary, the
Marginal remains in place across central Oklahoma, though it
appears likely the I-44 corridor from the Oklahoma City metro=20
through the Tulsa metro will see less in the way of total rainfall.

...Midwest...

The inherited Marginal Risk across Wisconsin and Illinois was
expanded just a bit to include the Green Bay, Milwaukee, and
Chicagoland regions with this update. A slow moving occluded front
attached to a low currently along the ND/MN border will push
eastward towards the western shores of Lake Michigan this
afternoon. Scattered showers and thunderstorms are likely to sweep
across the metros this afternoon and evening as a result, which
could themselves pose an urban and small stream flooding threat.
Behind the line, however, guidance suggests there could be
additional rainfall, most likely in the form of just showers, but
that will train over some of these same areas. Since guidance has
shifted a bit to the east with the greatest instability and
moisture advection this afternoon to along the Lake Michigan
shoreline, the urban I-94 & I-43 corridors were added to the
Marginal, which now generally spans from I-90/I-39 east to the=20
lakeshore.

...Central Appalachians...

The inherited Marginal Risk across portions of West Virginia was
nudged north just a bit in keeping with the latest guidance.
Generally areas east of the Appalachians should not be under much
flooding threat, as the heaviest rainfall remains in the portion of
eastern West Virginia from the southern tip of Maryland's western
Panhandle south to the Highland County, VA's northernmost point.
Guidance has been very consistent highlighting this area for the
most rainfall. Given the ongoing moderate to severe drought
conditions, it's likely there will be storms that may have embedded
heavy rain cores outside of the Marginal Risk area, but it will
take the persistence of heavy rain highlighted in this region in
the guidance to result in isolated instances of flash flooding.

Wegman

...Previous Discussion...

...Wisconsin and northern Illinois...

A negatively-tilted upper trough will lift slowly across the mid to
upper Mississippi Valley today. The associated ascent interacting
with a ribbon of relatively deeper moisture (PWs 1.25-1.5 inches)
along a modest low level jet will support showers and storms
redeveloping this afternoon, which may potentially continue into
the evening. With differences in the details, the CAMs generally
indicate two areas of locally heavier amounts -- a north-south axis
associated with storms lifting across eastern Wisconsin during the afternoon/evening and a west-east stripe produced by storms
developing across Iowa and then training across northern Illinois
later during the overnight. HREF neighborhood probabilities
indicate localized amounts in excess of 2 inches are possible in
these areas.

...Ozarks to southwestern Oklahoma....

CAMs indicate that ongoing convection firing north of a stationary
front over southern Kansas will continue through the late morning,
potentially producing heavy amounts as they train further east
into the Ozark Region. The HREF shows high neighborhood
probabilities for accumulations over 2 inches centered over this
region.

Then, as upstream energy sliding southeast across the central
Plains interacts with deepening moisture that will be supported by
increasing southerly low level flow, some guidance indicate that
storms will redevelop over this same area later today. However,
other models show storms developing further to the west before
moving back into areas impacted by this morning's storms.

While there is fair amount of uncertainty on how these storms
across central into eastern Oklahoma will evolve, there is greater
model consensus that storms developing over the Texas Panhandle and
western Oklahoma by this evening will merge across southwestern
Oklahoma to produce locally heavy amounts across the region during
the overnight.

...West Virginia...

CAMs continue to show isolated heavy amounts associated with slow-
moving storms that are expected to develop over eastern West
Virginia this afternoon. A weak impulse lifting northeast out of
the Ohio Valley, interacting with pooling moisture along a slowing
front, will support storm development. HREF neighborhood
probabilities indicate that amounts of 2-3 inches are likely within
the highlighted area.

Pereira


Day 2
Valid 12Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL PLAINS, MID MISSISSIPPI VALLEY, AND THE SOUTHWEST...

...Eastern Kansas and northeastern Oklahoma to southern Illinois...

Deepening moisture (PWs above 1.5 inches) along an axis of
strengthening southerly to southwesterly flow ahead an amplifying
upper trough will fuel showers and storms, possibly producing
heavy amounts. While models differ significantly on the details,
the general consensus indicates widespread precipitation is likely,
with locally heavy amounts of 1-2 inches possible.

...Southwest...

An upper low dropping to the south along the California coast will
slow as it becomes cutoff west of Southern California. Southerly
flow ahead of the system will support increasing moisture and the
chances for precipitation across parts of Southern California and
Arizona. Both the GFS and ECMWF show PW anomalies increasing to 2.5
to 3 standard deviations above normal across far Southern
California through the lower Colorado Basin into Arizona.

Pereira


Day 3
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHWEST AND FROM KANSAS AND OKLAHOMA TO THE OHIO VALLEY...

...Kansas and Oklahoma to the Ohio Valley...

Unsettled weather will continue, with the footprint for potentially
heavy rain expanding as energy moving through the base of a broad
upper trough interacts with deep moisture that will be supported
persistent southwesterly flow. While models generally agree on a
large footprint of moderate to heavy amounts, they lack agreement
on the details. At least locally heavy amounts are expected,
especially within the western portions of the highlighted area as
a well-defined shortwave dives southeast and is expected to
interact with a pool of deepening moisture along a strong
southwesterly low level jet. Given the indication of 2-3 inches in
some of the models, which is forecast to fall in addition to the
previous days' amounts, an upgrade to a Slight Risk may be
forthcoming if the signal persists and the guidance moves into
better agreement.

...Southwest...

An upper low is forecast to remain cutoff and drift slowly east
along the Southern California coast. Anomalous moisture in place
across Arizona is expected to spread east into parts of New Mexico,
extending the chances for showers and storms, with potentially
heavy amounts into the region.

Pereira


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4vorv7wPyzXg_TocNka6JuSEQZ0wkXx5Y4krahy1mdsO= ywtRd3H2PXjh4-Szwa30XMiQiWMhZ7SGqi52-TRdv12RGKw$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4vorv7wPyzXg_TocNka6JuSEQZ0wkXx5Y4krahy1mdsO= ywtRd3H2PXjh4-Szwa30XMiQiWMhZ7SGqi52-TRdBqbSoDk$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4vorv7wPyzXg_TocNka6JuSEQZ0wkXx5Y4krahy1mdsO= ywtRd3H2PXjh4-Szwa30XMiQiWMhZ7SGqi52-TRd9MJxIWo$=20

=3D =3D =3D
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FOUS30 KWBC 201854
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
254 PM EDT Sat Sep 20 2025

Day 1
Valid 16Z Sat Sep 20 2025 - 12Z Sun Sep 21 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE MIDWEST, THE SOUTHERN PLAINS AND OZARKS, AND THE CENTRAL
APPALACHIANS...

...16Z Update...

Overall, the 3 inherited Marginal Risk areas were only tweaked a
little bit each.

...Southern Plains and Ozarks...

An ongoing area of convection near the Moksarok continues to be a
Marginal flooding threat as the storms either linger or reform over
this same area later this afternoon. Most of the Moksarok has seen
about 1-2 inches of rain areally, but with locally higher amounts.
Thus, soils in this small region have become saturated enough that
additional rainfall from stronger storms later this afternoon could
cause isolated instances of flash flooding. Meanwhile, further
southwest, a secondary area of convection that is more aligned with
the core of the low level jet, will likely form very late tonight
across the Texas Panhandle, southwest Oklahoma and far north
Texas. These storms will pose an isolated overnight flash flooding
risk, and should be entirely separate from the storms ongoing near
the Moksarok. Since they will both be along the same boundary, the
Marginal remains in place across central Oklahoma, though it
appears likely the I-44 corridor from the Oklahoma City metro
through the Tulsa metro will see less in the way of total rainfall.

...Midwest...

The inherited Marginal Risk across Wisconsin and Illinois was
expanded just a bit to include the Green Bay, Milwaukee, and
Chicagoland regions with this update. A slow moving occluded front
attached to a low currently along the ND/MN border will push
eastward towards the western shores of Lake Michigan this
afternoon. Scattered showers and thunderstorms are likely to sweep
across the metros this afternoon and evening as a result, which
could themselves pose an urban and small stream flooding threat.
Behind the line, however, guidance suggests there could be
additional rainfall, most likely in the form of just showers, but
that will train over some of these same areas. Since guidance has
shifted a bit to the east with the greatest instability and
moisture advection this afternoon to along the Lake Michigan
shoreline, the urban I-94 & I-43 corridors were added to the
Marginal, which now generally spans from I-90/I-39 east to the
lakeshore.

...Central Appalachians...

The inherited Marginal Risk across portions of West Virginia was
nudged north just a bit in keeping with the latest guidance.
Generally areas east of the Appalachians should not be under much
flooding threat, as the heaviest rainfall remains in the portion of
eastern West Virginia from the southern tip of Maryland's western
Panhandle south to the Highland County, VA's northernmost point.
Guidance has been very consistent highlighting this area for the
most rainfall. Given the ongoing moderate to severe drought
conditions, it's likely there will be storms that may have embedded
heavy rain cores outside of the Marginal Risk area, but it will
take the persistence of heavy rain highlighted in this region in
the guidance to result in isolated instances of flash flooding.

Wegman

...Previous Discussion...

...Wisconsin and northern Illinois...

A negatively-tilted upper trough will lift slowly across the mid to
upper Mississippi Valley today. The associated ascent interacting
with a ribbon of relatively deeper moisture (PWs 1.25-1.5 inches)
along a modest low level jet will support showers and storms
redeveloping this afternoon, which may potentially continue into
the evening. With differences in the details, the CAMs generally
indicate two areas of locally heavier amounts -- a north-south axis
associated with storms lifting across eastern Wisconsin during the afternoon/evening and a west-east stripe produced by storms
developing across Iowa and then training across northern Illinois
later during the overnight. HREF neighborhood probabilities
indicate localized amounts in excess of 2 inches are possible in
these areas.

...Ozarks to southwestern Oklahoma....

CAMs indicate that ongoing convection firing north of a stationary
front over southern Kansas will continue through the late morning,
potentially producing heavy amounts as they train further east
into the Ozark Region. The HREF shows high neighborhood
probabilities for accumulations over 2 inches centered over this
region.

Then, as upstream energy sliding southeast across the central
Plains interacts with deepening moisture that will be supported by
increasing southerly low level flow, some guidance indicate that
storms will redevelop over this same area later today. However,
other models show storms developing further to the west before
moving back into areas impacted by this morning's storms.

While there is fair amount of uncertainty on how these storms
across central into eastern Oklahoma will evolve, there is greater
model consensus that storms developing over the Texas Panhandle and
western Oklahoma by this evening will merge across southwestern
Oklahoma to produce locally heavy amounts across the region during
the overnight.

...West Virginia...

CAMs continue to show isolated heavy amounts associated with slow-
moving storms that are expected to develop over eastern West
Virginia this afternoon. A weak impulse lifting northeast out of
the Ohio Valley, interacting with pooling moisture along a slowing
front, will support storm development. HREF neighborhood
probabilities indicate that amounts of 2-3 inches are likely within
the highlighted area.

Pereira


Day 2
Valid 12Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL PLAINS, MID MISSISSIPPI VALLEY, AND THE SOUTHWEST...

...19Z Update...

...Plains to Mid-Mississippi Valley...

Overall across the middle of the country, the signal for heavy rain
on Sunday remains quite diffuse. There will be a corridor where
heavier rain will be more likely, which includes the Marginal Risk
region from Oklahoma through Illinois. However, the guidance is in
otherwise poor agreement on where any clusters of storms will
develop and how much rain they will produce. Thus, taking
antecedent dry soil conditions into account across nearly all of
the Marginal Risk area, it remains a rather low-end Marginal.

...Southwest...

Very few changes needed across the Southwest as monsoonal moisture
in place across much of Arizona and portions of the California
Deserts may allow for some limited shower and thunderstorm
development. A positively tilted longwave trough approaching the
area from the northwest will increase the large scale forcing in
the area, which should allow for some "slopover" of any storms into
the normally drier desert areas. Couple that with the western
portion of the area (far southern California and far western
Arizona) having recently picked up locally flooding rains, the
Marginal Risk remains in place largely unchanged. As usual, burn
scar areas will be particularly susceptible to renewed flooding
should heavy rains occur over or near them.=20

Wegman

...Previous Discussion...

...Eastern Kansas and northeastern Oklahoma to southern Illinois...

Deepening moisture (PWs above 1.5 inches) along an axis of
strengthening southerly to southwesterly flow ahead an amplifying
upper trough will fuel showers and storms, possibly producing
heavy amounts. While models differ significantly on the details,
the general consensus indicates widespread precipitation is likely,
with locally heavy amounts of 1-2 inches possible.

...Southwest...

An upper low dropping to the south along the California coast will
slow as it becomes cutoff west of Southern California. Southerly
flow ahead of the system will support increasing moisture and the
chances for precipitation across parts of Southern California and
Arizona. Both the GFS and ECMWF show PW anomalies increasing to 2.5
to 3 standard deviations above normal across far Southern
California through the lower Colorado Basin into Arizona.

Pereira


Day 3
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHWEST AND FROM KANSAS AND OKLAHOMA TO THE OHIO VALLEY...

...19Z Update...

...Kansas/Oklahoma to the Ohio Valley...

A plume of moisture streaming off the Gulf will collide with a
stalled frontal boundary from Kansas through the Ohio Valley on
Monday. Expect multiple clusters of storms riding up that boundary
from southwest to northeast to douse the region with periodically
heavy rain. The details of where any such clusters of storms are
likely to form remain highly uncertain. Thus, while the signal for
heavy rain across the region is significantly higher than the Day
2/Sunday period, there remains little agreement on where and
whether any persistent heavy rain will significantly impact any
areas hit with heavy rain on previous days. Thus, once again taking
into account antecedent conditions, which only get drier the
further north and east you go, the large Marginal Risk area across
the area remains valid.

...Southwest...

Very little has changed in the forecast with another day of
afternoon showers and storms likely to impact much of eastern
Arizona into portions of western New Mexico Monday afternoon. With
ridging aloft and therefore no larger scale areas of forcing, the
storms will likely be tied to topography, such as the Mogollon Rim,
limiting the flash flood threat to isolated instances.

Wegman

...Previous Discussion...

...Kansas and Oklahoma to the Ohio Valley...

Unsettled weather will continue, with the footprint for potentially
heavy rain expanding as energy moving through the base of a broad
upper trough interacts with deep moisture that will be supported
persistent southwesterly flow. While models generally agree on a
large footprint of moderate to heavy amounts, they lack agreement
on the details. At least locally heavy amounts are expected,
especially within the western portions of the highlighted area as
a well-defined shortwave dives southeast and is expected to
interact with a pool of deepening moisture along a strong
southwesterly low level jet. Given the indication of 2-3 inches in
some of the models, which is forecast to fall in addition to the
previous days' amounts, an upgrade to a Slight Risk may be
forthcoming if the signal persists and the guidance moves into
better agreement.

...Southwest...

An upper low is forecast to remain cutoff and drift slowly east
along the Southern California coast. Anomalous moisture in place
across Arizona is expected to spread east into parts of New Mexico,
extending the chances for showers and storms, with potentially
heavy amounts into the region.

Pereira


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8OmcS63tFkaYvO5D2NPueyTVMjGpuy5Lzno_TkdNXzMG= uX1pGhJ5EK6BcWVUGJ7_QRKo9BLSbRvR8Mbowv1kGLrKVHg$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8OmcS63tFkaYvO5D2NPueyTVMjGpuy5Lzno_TkdNXzMG= uX1pGhJ5EK6BcWVUGJ7_QRKo9BLSbRvR8Mbowv1khYOuuUU$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8OmcS63tFkaYvO5D2NPueyTVMjGpuy5Lzno_TkdNXzMG= uX1pGhJ5EK6BcWVUGJ7_QRKo9BLSbRvR8Mbowv1klEZji-Y$=20

=3D =3D =3D
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FOUS30 KWBC 210039
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
839 PM EDT Sat Sep 20 2025

Day 1
Valid 01Z Sun Sep 21 2025 - 12Z Sun Sep 21 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHERN PLAINS, OZARKS, & CENTRAL APPALACHIANS...

...Southern Plains and Ozarks...
A festering area of convection across OK & near the MO/AR border continues
to be sufficient for a Marginal flooding threat. Earlier rainfall
should have partially saturated soils, and with the topography
across some locales, at least isolated instances of flash flooding
are anticipated. A later complex will likely form very late=20
tonight near the Red River of the South. These storms should also=20
pose an isolated overnight flash flooding risk. Regionally, there
is a pool of 1000-3500 J/kg of MU CAPE to feed thunderstorms and
about 25 kts of effective bulk shear which should lead to
organization at times. With precipitable water values ~1.5", hourly
amounts to 2" with local amounts to 4" should be possible.


...Central Appalachians...
Ongoing pulse convection should continue for several more hours=20
near the Virginia/West Virginia border before MU CAPE fades and/or=20
CIN wins out. Precipitable water values above 1.25" along with MU=20
CAPE of up to 1000 J/kg are feeding them currently. Until they=20
dissipate, hourly amounts to 2" are possible as they move slowly=20
near the rough topography, continuing the Marginal Risk of=20
excessive rainfall.

Roth


Day 2
Valid 12Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE CENTRAL PLAINS, MID MISSISSIPPI VALLEY, AND THE SOUTHWEST...

...19Z Update...

...Plains to Mid-Mississippi Valley...

Overall across the middle of the country, the signal for heavy rain
on Sunday remains quite diffuse. There will be a corridor where
heavier rain will be more likely, which includes the Marginal Risk
region from Oklahoma through Illinois. However, the guidance is in
otherwise poor agreement on where any clusters of storms will
develop and how much rain they will produce. Thus, taking
antecedent dry soil conditions into account across nearly all of
the Marginal Risk area, it remains a rather low-end Marginal.

...Southwest...

Very few changes needed across the Southwest as monsoonal moisture
in place across much of Arizona and portions of the California
Deserts may allow for some limited shower and thunderstorm
development. A positively tilted longwave trough approaching the
area from the northwest will increase the large scale forcing in
the area, which should allow for some "slopover" of any storms into
the normally drier desert areas. Couple that with the western
portion of the area (far southern California and far western
Arizona) having recently picked up locally flooding rains, the
Marginal Risk remains in place largely unchanged. As usual, burn
scar areas will be particularly susceptible to renewed flooding
should heavy rains occur over or near them.

Wegman

...Previous Discussion...

...Eastern Kansas and northeastern Oklahoma to southern Illinois...

Deepening moisture (PWs above 1.5 inches) along an axis of
strengthening southerly to southwesterly flow ahead an amplifying
upper trough will fuel showers and storms, possibly producing
heavy amounts. While models differ significantly on the details,
the general consensus indicates widespread precipitation is likely,
with locally heavy amounts of 1-2 inches possible.

...Southwest...

An upper low dropping to the south along the California coast will
slow as it becomes cutoff west of Southern California. Southerly
flow ahead of the system will support increasing moisture and the
chances for precipitation across parts of Southern California and
Arizona. Both the GFS and ECMWF show PW anomalies increasing to 2.5
to 3 standard deviations above normal across far Southern
California through the lower Colorado Basin into Arizona.

Pereira


Day 3
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS
OF THE SOUTHWEST AND FROM KANSAS AND OKLAHOMA TO THE OHIO VALLEY...

...19Z Update...

...Kansas/Oklahoma to the Ohio Valley...

A plume of moisture streaming off the Gulf will collide with a
stalled frontal boundary from Kansas through the Ohio Valley on
Monday. Expect multiple clusters of storms riding up that boundary
from southwest to northeast to douse the region with periodically
heavy rain. The details of where any such clusters of storms are
likely to form remain highly uncertain. Thus, while the signal for
heavy rain across the region is significantly higher than the Day
2/Sunday period, there remains little agreement on where and
whether any persistent heavy rain will significantly impact any
areas hit with heavy rain on previous days. Thus, once again taking
into account antecedent conditions, which only get drier the
further north and east you go, the large Marginal Risk area across
the area remains valid.

...Southwest...

Very little has changed in the forecast with another day of
afternoon showers and storms likely to impact much of eastern
Arizona into portions of western New Mexico Monday afternoon. With
ridging aloft and therefore no larger scale areas of forcing, the
storms will likely be tied to topography, such as the Mogollon Rim,
limiting the flash flood threat to isolated instances.

Wegman

...Previous Discussion...

...Kansas and Oklahoma to the Ohio Valley...

Unsettled weather will continue, with the footprint for potentially
heavy rain expanding as energy moving through the base of a broad
upper trough interacts with deep moisture that will be supported
persistent southwesterly flow. While models generally agree on a
large footprint of moderate to heavy amounts, they lack agreement
on the details. At least locally heavy amounts are expected,
especially within the western portions of the highlighted area as
a well-defined shortwave dives southeast and is expected to
interact with a pool of deepening moisture along a strong
southwesterly low level jet. Given the indication of 2-3 inches in
some of the models, which is forecast to fall in addition to the
previous days' amounts, an upgrade to a Slight Risk may be
forthcoming if the signal persists and the guidance moves into
better agreement.

...Southwest...

An upper low is forecast to remain cutoff and drift slowly east
along the Southern California coast. Anomalous moisture in place
across Arizona is expected to spread east into parts of New Mexico,
extending the chances for showers and storms, with potentially
heavy amounts into the region.

Pereira


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5dYUTd9YHCCo5BqlE_nbMUgURPa5l2yb1Rem_wl9VvKb= FhcyE-LhEl4C9yiWyMCBZUNQFvF60fl3YI89yJAdkURTWtk$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5dYUTd9YHCCo5BqlE_nbMUgURPa5l2yb1Rem_wl9VvKb= FhcyE-LhEl4C9yiWyMCBZUNQFvF60fl3YI89yJAdOOsCxlw$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5dYUTd9YHCCo5BqlE_nbMUgURPa5l2yb1Rem_wl9VvKb= FhcyE-LhEl4C9yiWyMCBZUNQFvF60fl3YI89yJAd8G0duIM$=20

=3D =3D =3D
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FOUS30 KWBC 210821
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
421 AM EDT Sun Sep 21 2025

Day 1
Valid 12Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE VICINITY OF
THE KANSAS/OKLAHOMA/ARKANSAS/MISSOURI BORDER AREA...

...Central-Southern Plains into the Mid Mississippi Valley...
Additional shortwave energy will be diving east southeastward=20
through the base of the mean trof centered through the Central to=20
Southern Plains into the Middle Mississippi Valley. These height=20
falls will help strengthen the low level west south west to=20
southwesterly flow into a west to east northeasterly oriented low=20
level boundary stretching from the Southern Plains into the Middle
Mississippi Valley. This will support another round of convection=20
pushing east from central to eastern KS/OK into much of MO,=20
northwest AR and central to Southern IL. A slight risk area was=20
added in the vicinity of the KS/OK/AR/MO border area that has seen=20
heavy rains over the past 24 hours and may see additional heavy=20
totals later in the upcoming day 1 period. Otherwise, there were no
significant changes made to the previous marginal risk area, that=20
continues to fit well with the latest axis of high HREF=20
neighborhood probabilities for 1 and 2"+ amounts during the=20
upcoming day 1 period. Across these areas, relative soil moistures=20
remain very low, which should help mitigate runoff issues, at least
initially.

...Southern California into Arizona...
The closed low initially off the Central California coast will be
drifting only slowly southward day 1 to a position off the=20
Southern California coast. A jet streak on the eastern side of this
upper trof will keep favorable right entrance region jet dynamics=20
over Southern CA into Arizona. This will help accentuate lift in=20
an axis of anomalous PW values, 1 to 3+ standard deviations above=20
the mean that are expected to persist across these areas day 1.=20
This should support potential for additional widespread scattered=20 convection, locally heavy rains and isolated runoff issues.

Oravec

Day 2
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE=20=20
CENTRAL TO SOUTHERN PLAINS, MIDDLE TO LOWER MISSISSIPPI VALLEY AND=20
OHIO VALLEY AND ACROSS ARIZONA INTO WESTERN NEW MEXICO...

...Mid to Lower Mississippi Valley into the Ohio Valley...
The height falls pushing east southeastward day 1 into the Central
to Southern Plains and toward the Mid Mississippi Valley will=20
continue to move eastward through the Ohio Valley day 2. Well=20
defined large scale lift in an axis of above average PW values, 1=20
to 1.5+ standard deviations above the mean, will support the=20
likelihood of widespread moderate to heavy precipitation in an=20
axis from northern AR, far southeast MO, far southeast IL, western=20
to central KY, much of IN and OH. At the moment the convection=20
across these areas may be fairly progressive. This and very low=20
relative soil moistures, much of the area in moderate to severe=20
drought, will keep the risk level at marginal for the time being.=20
With respect to changes to the previous issuance, the northern edge
of the marginal risk was trimmed to the south by about 50-75 miles
to account for the latest model consensus.

...Central to Southern Plains...
The marginal risk area from the previous issuance was expanded=20
slightly westward into western KS to cover the model spread with
the next round of convection forming ahead of the upstream
amplifying height falls dropping southeastward late=20
day 1 from the Northern Rockies into the Central Rockies/Lee of the
Central Rockies on day 2. The GFS and NAM begin to diverge day 2=20
with the track of this closing off mid to upper level center, with=20
the NAM taking a more southeastward track into the Central Plains,=20
while the GFS takes a more south southeastward track into the=20
Central Rockies. The NAM solution, at the moment, is an outlier=20
with the EC, UKMET and CMC more in line with the GFS. The
differing mid to upper evolutions have more of a qpf impact over
south central WY into north central CO, where the more southeast
NAM solution is much lighter than the remainder of the guidance. Do
not believe there will be any runoff issues farther northwest
across CO/WY given lack of instability. While models differ farther
to the southeast, there are still non NAM solutions that have
potentially heavy rains as far northwest as northwest KS day 2,
supporting the west northwest expansion from the previous=20
issuance.

...Southwest...
The closed low off the Southern CA coast day 1 is expected to move
little on day 2. The right entrance region of the jet streak to=20
the east of this closed low will push eastward from its day 1=20
position, but continue to support uvvs enhancement in the above=20
average PW axis, 1 to 3 standard deviations above the mean, that=20
will remain in place across Southern CA into the Southwest.=20
Additional scattered convection across these areas will support=20
localized heavy amounts and isolated runoff issues. The previous=20
marginal risk area was expanded westward into southeast CA to cover
the model qpf spread.

Oravec

Day 3
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, NORTHERN ARKANSAS, NORTHEAST OKLAHOMA AND SOUTHEAST=20
KANSAS...

There continues to be model differences in the evolution of the mid
to upper level trof over the Central to Southern Plains toward the
Mid Mississippi Valley. The NAM continues to be an outlier in being
more amplified and faster to push the height falls downstream.
Despite the differences, models do show re-strengthening of the low
level southwesterly flow ahead of surface low pressure moving east
across Oklahoma into Arkansas. This will support potential for
organized convection, that likely forms late day 2 to the north of
this low across the Central Plains, continuing day 3 from southeast KS/northeast OK, across Southern MO and northern AR. Model
consensus is for the heaviest totals across these areas with
amounts of 2-4" possible. This heavy axis will possibly overlap
where heavy rains have fallen over the past 24 hours and where=20
additional heavy rains are possible during the day 1 period. There=20
were no major changes to the slight risk area from the previous=20
issuance. The marginal risk was extended farther westward into=20
northeast CO where several models show heavy rain potential day 3.=20
The eastern portion of the marginal risk was also extended into the
Upper OH Valley to cover the model qpf spread.=20

...Southern to Central California...
The nearly stationary closed low off the Southern CA coast day 2=20
will begin to slowly move back to the north on day 3 toward the=20
Central CA coast. This slow north movement will also allow for a=20
northward expansion of the anomalous PW values over Southern CA=20
into Central CA, with values as high as 3-4 standard deviations=20
above the mean. There are differences with qpf distributions given
differences with the northward push of the closed low. Not a lot=20
of confidence in any solution at this range, but continued=20
potential for locally heavy rains and isolated runoff issues,=20
especially over any burn scars. No changes made at the moment to=20
the previous broad marginal risk area over Southern to Central CA.

Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7a4XPBhPnupSTC6VH9finfNizRCPOtguJLc-5B9snVhV= H-SLLw0oUkaakzVj543lA06WtwL9oqC0dV7Ztx1t16xGtgU$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7a4XPBhPnupSTC6VH9finfNizRCPOtguJLc-5B9snVhV= H-SLLw0oUkaakzVj543lA06WtwL9oqC0dV7Ztx1tR_grx6s$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7a4XPBhPnupSTC6VH9finfNizRCPOtguJLc-5B9snVhV= H-SLLw0oUkaakzVj543lA06WtwL9oqC0dV7Ztx1twaZjM2Y$=20

=3D =3D =3D
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FOUS30 KWBC 211600
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1200 PM EDT Sun Sep 21 2025

Day 1
Valid 16Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE VICINITY OF
THE KANSAS/OKLAHOMA/ARKANSAS/MISSOURI BORDER AREA...

...16Z Update...

...Central/Southern Plains to the Mid-Mississippi Valley...

The inherited Slight Risk for portions of the
Missouri/Kansas/Oklahoma/Arkansas region has been expanded=20
southward across much of far eastern Oklahoma with this update. 12Z
guidance has some agreement that once the area of showers and=20
storms moving along the OK/TX border moves through eastern Oklahoma
and into Arkansas later this afternoon, a renewed area of=20
convection forms along a trailing boundary somewhere in eastern=20
Oklahoma. While the agreement on where that trailing boundary will=20
set up is poor, there is far better agreement that it may result in
multiple hours of trailing thunderstorms in a narrow corridor=20
aligned northwest to southeast. Perhaps with some persistence bias=20
given the events of last night where narrow corridors of 4-6 inches
of rain fell further north, resulting in localized flash flooding,
confidence has increased for such an event to occur again a bit=20
further south tonight. While rainfall amounts are expected to be
lesser in this area tonight, any additional rainfall on top of
areas hard hit tonight could cause renewed stream, creek, and river
rises, so the Slight Risk in that area is maintained.

Further north into Missouri, there is less confidence due to lesser instability. While the potential for training is high, how strong
those storms get and how long they persist and where those most
persistent bands set up across Missouri and into Illinois is of low
certainty. Thus, for now the Marginal is maintained, but the Slight
may need to be expanded on short-notice should the storms show the
ability to produce heavy rains for an extended period of time.

...Southwest...

Few changes were needed, as the forecast described below in the
previous discussion remains valid.

Wegman

...Previous Discussion...

...Central-Southern Plains into the Mid Mississippi Valley...
Additional shortwave energy will be diving east southeastward
through the base of the mean trof centered through the Central to
Southern Plains into the Middle Mississippi Valley. These height
falls will help strengthen the low level west south west to
southwesterly flow into a west to east northeasterly oriented low
level boundary stretching from the Southern Plains into the Middle
Mississippi Valley. This will support another round of convection
pushing east from central to eastern KS/OK into much of MO,
northwest AR and central to Southern IL. A slight risk area was
added in the vicinity of the KS/OK/AR/MO border area that has seen
heavy rains over the past 24 hours and may see additional heavy
totals later in the upcoming day 1 period. Otherwise, there were no
significant changes made to the previous marginal risk area, that
continues to fit well with the latest axis of high HREF
neighborhood probabilities for 1 and 2"+ amounts during the
upcoming day 1 period. Across these areas, relative soil moistures
remain very low, which should help mitigate runoff issues, at least
initially.

...Southern California into Arizona...
The closed low initially off the Central California coast will be
drifting only slowly southward day 1 to a position off the
Southern California coast. A jet streak on the eastern side of this
upper trof will keep favorable right entrance region jet dynamics
over Southern CA into Arizona. This will help accentuate lift in
an axis of anomalous PW values, 1 to 3+ standard deviations above
the mean that are expected to persist across these areas day 1.
This should support potential for additional widespread scattered
convection, locally heavy rains and isolated runoff issues.

Oravec

Day 2
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE
CENTRAL TO SOUTHERN PLAINS, MIDDLE TO LOWER MISSISSIPPI VALLEY AND
OHIO VALLEY AND ACROSS ARIZONA INTO WESTERN NEW MEXICO...

...Mid to Lower Mississippi Valley into the Ohio Valley...
The height falls pushing east southeastward day 1 into the Central
to Southern Plains and toward the Mid Mississippi Valley will
continue to move eastward through the Ohio Valley day 2. Well
defined large scale lift in an axis of above average PW values, 1
to 1.5+ standard deviations above the mean, will support the
likelihood of widespread moderate to heavy precipitation in an
axis from northern AR, far southeast MO, far southeast IL, western
to central KY, much of IN and OH. At the moment the convection
across these areas may be fairly progressive. This and very low
relative soil moistures, much of the area in moderate to severe
drought, will keep the risk level at marginal for the time being.
With respect to changes to the previous issuance, the northern edge
of the marginal risk was trimmed to the south by about 50-75 miles
to account for the latest model consensus.

...Central to Southern Plains...
The marginal risk area from the previous issuance was expanded
slightly westward into western KS to cover the model spread with
the next round of convection forming ahead of the upstream
amplifying height falls dropping southeastward late
day 1 from the Northern Rockies into the Central Rockies/Lee of the
Central Rockies on day 2. The GFS and NAM begin to diverge day 2
with the track of this closing off mid to upper level center, with
the NAM taking a more southeastward track into the Central Plains,
while the GFS takes a more south southeastward track into the
Central Rockies. The NAM solution, at the moment, is an outlier
with the EC, UKMET and CMC more in line with the GFS. The
differing mid to upper evolutions have more of a qpf impact over
south central WY into north central CO, where the more southeast
NAM solution is much lighter than the remainder of the guidance. Do
not believe there will be any runoff issues farther northwest
across CO/WY given lack of instability. While models differ farther
to the southeast, there are still non NAM solutions that have
potentially heavy rains as far northwest as northwest KS day 2,
supporting the west northwest expansion from the previous
issuance.

...Southwest...
The closed low off the Southern CA coast day 1 is expected to move
little on day 2. The right entrance region of the jet streak to
the east of this closed low will push eastward from its day 1
position, but continue to support uvvs enhancement in the above
average PW axis, 1 to 3 standard deviations above the mean, that
will remain in place across Southern CA into the Southwest.
Additional scattered convection across these areas will support
localized heavy amounts and isolated runoff issues. The previous
marginal risk area was expanded westward into southeast CA to cover
the model qpf spread.

Oravec

Day 3
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, NORTHERN ARKANSAS, NORTHEAST OKLAHOMA AND SOUTHEAST
KANSAS...

There continues to be model differences in the evolution of the mid
to upper level trof over the Central to Southern Plains toward the
Mid Mississippi Valley. The NAM continues to be an outlier in being
more amplified and faster to push the height falls downstream.
Despite the differences, models do show re-strengthening of the low
level southwesterly flow ahead of surface low pressure moving east
across Oklahoma into Arkansas. This will support potential for
organized convection, that likely forms late day 2 to the north of
this low across the Central Plains, continuing day 3 from southeast KS/northeast OK, across Southern MO and northern AR. Model
consensus is for the heaviest totals across these areas with
amounts of 2-4" possible. This heavy axis will possibly overlap
where heavy rains have fallen over the past 24 hours and where
additional heavy rains are possible during the day 1 period. There
were no major changes to the slight risk area from the previous
issuance. The marginal risk was extended farther westward into
northeast CO where several models show heavy rain potential day 3.
The eastern portion of the marginal risk was also extended into the
Upper OH Valley to cover the model qpf spread.

...Southern to Central California...
The nearly stationary closed low off the Southern CA coast day 2
will begin to slowly move back to the north on day 3 toward the
Central CA coast. This slow north movement will also allow for a
northward expansion of the anomalous PW values over Southern CA
into Central CA, with values as high as 3-4 standard deviations
above the mean. There are differences with qpf distributions given
differences with the northward push of the closed low. Not a lot
of confidence in any solution at this range, but continued
potential for locally heavy rains and isolated runoff issues,
especially over any burn scars. No changes made at the moment to
the previous broad marginal risk area over Southern to Central CA.

Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_5UsLwW_eu2rF1FjfyQGvaVBr7V1tf5So_rFXDDMpaTc= 15dP6e8YyZhEE0di6PiYzab1SUeMVl1joYCWdRVc9WYLsF0$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_5UsLwW_eu2rF1FjfyQGvaVBr7V1tf5So_rFXDDMpaTc= 15dP6e8YyZhEE0di6PiYzab1SUeMVl1joYCWdRVcDESC76U$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_5UsLwW_eu2rF1FjfyQGvaVBr7V1tf5So_rFXDDMpaTc= 15dP6e8YyZhEE0di6PiYzab1SUeMVl1joYCWdRVcfEaLhrY$=20

=3D =3D =3D
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FOUS30 KWBC 211902
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
302 PM EDT Sun Sep 21 2025

Day 1
Valid 16Z Sun Sep 21 2025 - 12Z Mon Sep 22 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN THE VICINITY OF
THE KANSAS/OKLAHOMA/ARKANSAS/MISSOURI BORDER AREA...

...16Z Update...

...Central/Southern Plains to the Mid-Mississippi Valley...

The inherited Slight Risk for portions of the
Missouri/Kansas/Oklahoma/Arkansas region has been expanded
southward across much of far eastern Oklahoma with this update. 12Z
guidance has some agreement that once the area of showers and
storms moving along the OK/TX border moves through eastern Oklahoma
and into Arkansas later this afternoon, a renewed area of
convection forms along a trailing boundary somewhere in eastern
Oklahoma. While the agreement on where that trailing boundary will
set up is poor, there is far better agreement that it may result in
multiple hours of trailing thunderstorms in a narrow corridor
aligned northwest to southeast. Perhaps with some persistence bias
given the events of last night where narrow corridors of 4-6 inches
of rain fell further north, resulting in localized flash flooding,
confidence has increased for such an event to occur again a bit
further south tonight. While rainfall amounts are expected to be
lesser in this area tonight, any additional rainfall on top of
areas hard hit tonight could cause renewed stream, creek, and river
rises, so the Slight Risk in that area is maintained.

Further north into Missouri, there is less confidence due to lesser instability. While the potential for training is high, how strong
those storms get and how long they persist and where those most
persistent bands set up across Missouri and into Illinois is of low
certainty. Thus, for now the Marginal is maintained, but the Slight
may need to be expanded on short-notice should the storms show the
ability to produce heavy rains for an extended period of time.

...Southwest...

Few changes were needed, as the forecast described below in the
previous discussion remains valid.

Wegman

...Previous Discussion...

...Central-Southern Plains into the Mid Mississippi Valley...
Additional shortwave energy will be diving east southeastward
through the base of the mean trof centered through the Central to
Southern Plains into the Middle Mississippi Valley. These height
falls will help strengthen the low level west south west to
southwesterly flow into a west to east northeasterly oriented low
level boundary stretching from the Southern Plains into the Middle
Mississippi Valley. This will support another round of convection
pushing east from central to eastern KS/OK into much of MO,
northwest AR and central to Southern IL. A slight risk area was
added in the vicinity of the KS/OK/AR/MO border area that has seen
heavy rains over the past 24 hours and may see additional heavy
totals later in the upcoming day 1 period. Otherwise, there were no
significant changes made to the previous marginal risk area, that
continues to fit well with the latest axis of high HREF
neighborhood probabilities for 1 and 2"+ amounts during the
upcoming day 1 period. Across these areas, relative soil moistures
remain very low, which should help mitigate runoff issues, at least
initially.

...Southern California into Arizona...
The closed low initially off the Central California coast will be
drifting only slowly southward day 1 to a position off the
Southern California coast. A jet streak on the eastern side of this
upper trof will keep favorable right entrance region jet dynamics
over Southern CA into Arizona. This will help accentuate lift in
an axis of anomalous PW values, 1 to 3+ standard deviations above
the mean that are expected to persist across these areas day 1.
This should support potential for additional widespread scattered
convection, locally heavy rains and isolated runoff issues.

Oravec

Day 2
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE
CENTRAL TO SOUTHERN PLAINS, MIDDLE TO LOWER MISSISSIPPI VALLEY AND
OHIO VALLEY AND ACROSS ARIZONA INTO WESTERN NEW MEXICO...

19z Update: There may be an opportunity to add in a Slight risk or
two on future updates, by for now we will maintain the broad
Marginal risk from portions of the Plains into the OH and TN=20
Valley. The 12z high res guidance indicates one area of heavier
rainfall (upwards of 2-4") across portions of central KY and TN.
Considered a targeted Slight risk here, but this is a notable QPF
uptick from the previous cycle, and would prefer to wait for
another cycle to see if the signal remains consistent. On top of=20
that, FFG is quite high over this area, and so even with the=20
increased QPF signal the HREF probabilities of exceeding 3hr FFG=20
remain low.

Another area to watch is western to central KS into northern OK where
a convective complex is expected Monday night into early Tuesday.=20
At least some training appears probable, but the extent remains a=20
bit uncertain. Thus the Marginal risk should suffice for now.

Chenard

...Previous Discussion...

...Mid to Lower Mississippi Valley into the Ohio Valley...
The height falls pushing east southeastward day 1 into the Central
to Southern Plains and toward the Mid Mississippi Valley will
continue to move eastward through the Ohio Valley day 2. Well
defined large scale lift in an axis of above average PW values, 1
to 1.5+ standard deviations above the mean, will support the
likelihood of widespread moderate to heavy precipitation in an
axis from northern AR, far southeast MO, far southeast IL, western
to central KY, much of IN and OH. At the moment the convection
across these areas may be fairly progressive. This and very low
relative soil moistures, much of the area in moderate to severe
drought, will keep the risk level at marginal for the time being.
With respect to changes to the previous issuance, the northern edge
of the marginal risk was trimmed to the south by about 50-75 miles
to account for the latest model consensus.

...Central to Southern Plains...
The marginal risk area from the previous issuance was expanded
slightly westward into western KS to cover the model spread with
the next round of convection forming ahead of the upstream
amplifying height falls dropping southeastward late
day 1 from the Northern Rockies into the Central Rockies/Lee of the
Central Rockies on day 2. The GFS and NAM begin to diverge day 2
with the track of this closing off mid to upper level center, with
the NAM taking a more southeastward track into the Central Plains,
while the GFS takes a more south southeastward track into the
Central Rockies. The NAM solution, at the moment, is an outlier
with the EC, UKMET and CMC more in line with the GFS. The
differing mid to upper evolutions have more of a qpf impact over
south central WY into north central CO, where the more southeast
NAM solution is much lighter than the remainder of the guidance. Do
not believe there will be any runoff issues farther northwest
across CO/WY given lack of instability. While models differ farther
to the southeast, there are still non NAM solutions that have
potentially heavy rains as far northwest as northwest KS day 2,
supporting the west northwest expansion from the previous
issuance.

...Southwest...
The closed low off the Southern CA coast day 1 is expected to move
little on day 2. The right entrance region of the jet streak to
the east of this closed low will push eastward from its day 1
position, but continue to support uvvs enhancement in the above
average PW axis, 1 to 3 standard deviations above the mean, that
will remain in place across Southern CA into the Southwest.
Additional scattered convection across these areas will support
localized heavy amounts and isolated runoff issues. The previous
marginal risk area was expanded westward into southeast CA to cover
the model qpf spread.

Oravec

Day 3
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, NORTHERN ARKANSAS, NORTHEAST OKLAHOMA AND SOUTHEAST
KANSAS...

19z Update: On Tuesday an uptick in the flash flood risk is=20
expected across portions of eastern OK, southeast KS, southern MO=20
and northern AR. Mid level shortwave energy, favorable upper jet
dynamics and strong low level moisture transport all support an
organized convective risk. Model instability forecasts are
sufficient for deep convection capable of heavy rainfall rates,=20
and PWs of at least 1-2 SD above average are expected. The current=20
model consensus is for the max rainfall axis to stretch from west=20
to east near the AR/MO border. This axis also saw heavy rainfall=20
last night, and could very well see additional areas of heavier=20
rain through Monday. When considering these antecedent conditions,
an upgrade to a MDT risk may be needed on future updates across=20
portions of the area. However, we are still pretty far out, and=20
there remains some latitudinal spread with the heaviest rainfall=20
axis. This event will soon move into the range of more of the high=20
res models, at which point we will likely see some fine tuning and=20
adjusting of the rainfall axis and magnitudes. Thus we will hold=20
off on any upgrade, and still consider this a higher end Slight=20
risk area. Either way would expect at least scattered instances of
flash flooding Tuesday, some of which could be locally considerable.

Chenard

...Previous Discussion...

There continues to be model differences in the evolution of the mid
to upper level trof over the Central to Southern Plains toward the
Mid Mississippi Valley. The NAM continues to be an outlier in being
more amplified and faster to push the height falls downstream.
Despite the differences, models do show re-strengthening of the low
level southwesterly flow ahead of surface low pressure moving east
across Oklahoma into Arkansas. This will support potential for
organized convection, that likely forms late day 2 to the north of
this low across the Central Plains, continuing day 3 from southeast KS/northeast OK, across Southern MO and northern AR. Model
consensus is for the heaviest totals across these areas with
amounts of 2-4" possible. This heavy axis will possibly overlap
where heavy rains have fallen over the past 24 hours and where
additional heavy rains are possible during the day 1 period. There
were no major changes to the slight risk area from the previous
issuance. The marginal risk was extended farther westward into
northeast CO where several models show heavy rain potential day 3.
The eastern portion of the marginal risk was also extended into the
Upper OH Valley to cover the model qpf spread.

...Southern to Central California...
The nearly stationary closed low off the Southern CA coast day 2
will begin to slowly move back to the north on day 3 toward the
Central CA coast. This slow north movement will also allow for a
northward expansion of the anomalous PW values over Southern CA
into Central CA, with values as high as 3-4 standard deviations
above the mean. There are differences with qpf distributions given
differences with the northward push of the closed low. Not a lot
of confidence in any solution at this range, but continued
potential for locally heavy rains and isolated runoff issues,
especially over any burn scars. No changes made at the moment to
the previous broad marginal risk area over Southern to Central CA.

Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!53vZvBQjfeVOLpokbfnH09UBUnsiIhQycEtcm6bf2K9U= MBmjS7vMUF4hwmskHlj62euYqyxNkTTRnlXgtWTWxmlIigg$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!53vZvBQjfeVOLpokbfnH09UBUnsiIhQycEtcm6bf2K9U= MBmjS7vMUF4hwmskHlj62euYqyxNkTTRnlXgtWTWvkAhyQ4$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!53vZvBQjfeVOLpokbfnH09UBUnsiIhQycEtcm6bf2K9U= MBmjS7vMUF4hwmskHlj62euYqyxNkTTRnlXgtWTWVyGByEs$=20

=3D =3D =3D
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FOUS30 KWBC 220046
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
846 PM EDT Sun Sep 21 2025

Day 1
Valid 01Z Mon Sep 22 2025 - 12Z Mon Sep 22 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN AND NEAR
NORTHWEST ARKANSAS...

...Central-Southern Plains into the Mid Mississippi Valley...
While an initial shortwave is moving towards the MO/AR/OK border
junction currently, another shortwave is upstream across eastern
KS. Fairly unidirectional flow out of the west-southwest will exist
ahead of the KS shortwave. Along with 25-35 kts of effective bulk
shear and a broad area of 500-1500 J/kg of MU CAPE will support=20
continued convection from southeast OK through northwest AR into
southern MO. Adding to the flash flood sensitivity is heavy=20
rainfall which occurred across portions of northeast OK, northwest=20
AR, and southwest MO over the past 24 hours. A Slight Risk area=20
remains across portions of this region, which were advised by
continuity, radar reflectivity trends, the 18z HREF, and the 12z=20
REFS guidance.


...Southern California into Arizona...
An upper level trough across central CA will keep favorable right=20
entrance region jet dynamics over Southern CA into Arizona. While
ongoing convection has been mainly constrained to southeast AZ,
some of the mesoscale guidance suggests renewed activity across
portions of western and central AZ as the upper level trough
interacts with lingering 500-3000 J/kg of MU CAPE, with more than=20
sufficient effective bulk shear available to organize convection.=20
As moisture remains above average here as well, locally heavy rains
and isolated runoff issues are expected intermittently through=20
12z.


...Southern Minnesota...
Convection under the base of an upper level low moving across
central MN is expected to persist overnight within an environment
of 1.25"+ precipitable water values and 1000-2000 J/kg of MU CAPE,
with plentiful effective bulk shear to potentially enhance=20
convective organization. Given the moisture values, believe any
heavy rain-related issues would be isolated. Added a Marginal Risk
into this area per the ingredients listed above and the 12z=20
REFS/18z HREF probabilities of 2"+ through 12z. Hourly amounts to
1.5" with local totals to 3" are possible where cells manage to
train and/or merge.

Roth


Day 2
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL FROM THE
CENTRAL TO SOUTHERN PLAINS, MIDDLE TO LOWER MISSISSIPPI VALLEY AND
OHIO VALLEY AND ACROSS ARIZONA INTO WESTERN NEW MEXICO...

19z Update: There may be an opportunity to add in a Slight risk or
two on future updates, by for now we will maintain the broad
Marginal risk from portions of the Plains into the OH and TN
Valley. The 12z high res guidance indicates one area of heavier
rainfall (upwards of 2-4") across portions of central KY and TN.
Considered a targeted Slight risk here, but this is a notable QPF
uptick from the previous cycle, and would prefer to wait for
another cycle to see if the signal remains consistent. On top of
that, FFG is quite high over this area, and so even with the
increased QPF signal the HREF probabilities of exceeding 3hr FFG
remain low.

Another area to watch is western to central KS into northern OK where
a convective complex is expected Monday night into early Tuesday.
At least some training appears probable, but the extent remains a
bit uncertain. Thus the Marginal risk should suffice for now.

Chenard

...Previous Discussion...

...Mid to Lower Mississippi Valley into the Ohio Valley...
The height falls pushing east southeastward day 1 into the Central
to Southern Plains and toward the Mid Mississippi Valley will
continue to move eastward through the Ohio Valley day 2. Well
defined large scale lift in an axis of above average PW values, 1
to 1.5+ standard deviations above the mean, will support the
likelihood of widespread moderate to heavy precipitation in an
axis from northern AR, far southeast MO, far southeast IL, western
to central KY, much of IN and OH. At the moment the convection
across these areas may be fairly progressive. This and very low
relative soil moistures, much of the area in moderate to severe
drought, will keep the risk level at marginal for the time being.
With respect to changes to the previous issuance, the northern edge
of the marginal risk was trimmed to the south by about 50-75 miles
to account for the latest model consensus.

...Central to Southern Plains...
The marginal risk area from the previous issuance was expanded
slightly westward into western KS to cover the model spread with
the next round of convection forming ahead of the upstream
amplifying height falls dropping southeastward late
day 1 from the Northern Rockies into the Central Rockies/Lee of the
Central Rockies on day 2. The GFS and NAM begin to diverge day 2
with the track of this closing off mid to upper level center, with
the NAM taking a more southeastward track into the Central Plains,
while the GFS takes a more south southeastward track into the
Central Rockies. The NAM solution, at the moment, is an outlier
with the EC, UKMET and CMC more in line with the GFS. The
differing mid to upper evolutions have more of a qpf impact over
south central WY into north central CO, where the more southeast
NAM solution is much lighter than the remainder of the guidance. Do
not believe there will be any runoff issues farther northwest
across CO/WY given lack of instability. While models differ farther
to the southeast, there are still non NAM solutions that have
potentially heavy rains as far northwest as northwest KS day 2,
supporting the west northwest expansion from the previous
issuance.

...Southwest...
The closed low off the Southern CA coast day 1 is expected to move
little on day 2. The right entrance region of the jet streak to
the east of this closed low will push eastward from its day 1
position, but continue to support uvvs enhancement in the above
average PW axis, 1 to 3 standard deviations above the mean, that
will remain in place across Southern CA into the Southwest.
Additional scattered convection across these areas will support
localized heavy amounts and isolated runoff issues. The previous
marginal risk area was expanded westward into southeast CA to cover
the model qpf spread.

Oravec

Day 3
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, NORTHERN ARKANSAS, NORTHEAST OKLAHOMA AND SOUTHEAST
KANSAS...

19z Update: On Tuesday an uptick in the flash flood risk is
expected across portions of eastern OK, southeast KS, southern MO
and northern AR. Mid level shortwave energy, favorable upper jet
dynamics and strong low level moisture transport all support an
organized convective risk. Model instability forecasts are
sufficient for deep convection capable of heavy rainfall rates,
and PWs of at least 1-2 SD above average are expected. The current
model consensus is for the max rainfall axis to stretch from west
to east near the AR/MO border. This axis also saw heavy rainfall
last night, and could very well see additional areas of heavier
rain through Monday. When considering these antecedent conditions,
an upgrade to a MDT risk may be needed on future updates across
portions of the area. However, we are still pretty far out, and
there remains some latitudinal spread with the heaviest rainfall
axis. This event will soon move into the range of more of the high
res models, at which point we will likely see some fine tuning and
adjusting of the rainfall axis and magnitudes. Thus we will hold
off on any upgrade, and still consider this a higher end Slight
risk area. Either way would expect at least scattered instances of
flash flooding Tuesday, some of which could be locally considerable.

Chenard

...Previous Discussion...

There continues to be model differences in the evolution of the mid
to upper level trof over the Central to Southern Plains toward the
Mid Mississippi Valley. The NAM continues to be an outlier in being
more amplified and faster to push the height falls downstream.
Despite the differences, models do show re-strengthening of the low
level southwesterly flow ahead of surface low pressure moving east
across Oklahoma into Arkansas. This will support potential for
organized convection, that likely forms late day 2 to the north of
this low across the Central Plains, continuing day 3 from southeast KS/northeast OK, across Southern MO and northern AR. Model
consensus is for the heaviest totals across these areas with
amounts of 2-4" possible. This heavy axis will possibly overlap
where heavy rains have fallen over the past 24 hours and where
additional heavy rains are possible during the day 1 period. There
were no major changes to the slight risk area from the previous
issuance. The marginal risk was extended farther westward into
northeast CO where several models show heavy rain potential day 3.
The eastern portion of the marginal risk was also extended into the
Upper OH Valley to cover the model qpf spread.

...Southern to Central California...
The nearly stationary closed low off the Southern CA coast day 2
will begin to slowly move back to the north on day 3 toward the
Central CA coast. This slow north movement will also allow for a
northward expansion of the anomalous PW values over Southern CA
into Central CA, with values as high as 3-4 standard deviations
above the mean. There are differences with qpf distributions given
differences with the northward push of the closed low. Not a lot
of confidence in any solution at this range, but continued
potential for locally heavy rains and isolated runoff issues,
especially over any burn scars. No changes made at the moment to
the previous broad marginal risk area over Southern to Central CA.

Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!89DQGVhHmg8BsgSkY1cstxr58Oofnh1tlb8fZWzWw-CZ= TPjBP-9z2Mh_WmDRg4l9C5ERosBnoUHnVsQ0xzckXP0FuJc$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!89DQGVhHmg8BsgSkY1cstxr58Oofnh1tlb8fZWzWw-CZ= TPjBP-9z2Mh_WmDRg4l9C5ERosBnoUHnVsQ0xzckPdPtY_E$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!89DQGVhHmg8BsgSkY1cstxr58Oofnh1tlb8fZWzWw-CZ= TPjBP-9z2Mh_WmDRg4l9C5ERosBnoUHnVsQ0xzckjhFycl8$=20

=3D =3D =3D
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FOUS30 KWBC 220821
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
421 AM EDT Mon Sep 22 2025

Day 1
Valid 12Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTH
CENTRAL KANSAS INTO NORTH CENTRAL OKLAHOMA...

...Central to Southern Plains...
The latest model suite is in better agreement with the evolution=20
of the amplifying upper trof across the Northern to Central Rockies
day 1 and the downstream outbreak of organized convection along=20
and to the north of the path of the associated surface low moving=20
west to east from the TX Panhandle into western OK. A slight risk=20
area was added for the potential for organized convection along and
to the north of this low, across areas of south-central KS into=20 north-central OK where the low level southerly flow will be
strengthening and the corresponding 850-700 mb moisture flux
becoming anomalous, upwards to 2 to 3 standard deviations above=20
the mean by the end of the day 1 period. The neighborhood=20
probabilities are high in both the HREF and RRFS for 1 and 2"+=20
amounts across these areas. Additionally, both the HREF and RRFS=20
show a defined area of probabilities exceeding the 3 hourly FFG=20
values in the 0000-1200 UTC Tuesday time frame as the potentially=20
organized convection presses east southeastward.=20

...Mid to Lower Mississippi Valley into the Ohio Valley...
A broad marginal risk area was maintained in association with height
falls pushing east northeastward from the Mid Mississippi Valley=20
through the Ohio Valley. Well defined large scale lift in an axis=20
of above average PW values, 1 to 1.5+ standard deviations above the
mean, will support the likelihood of widespread moderate to heavy=20 precipitation in an axis from northern AR, far southeast MO, far=20
southeast IL, western to central KY, much of IN and OH. At the=20
moment the convection across these areas may be fairly progressive.
This and very low relative soil moistures, much of the area in=20
moderate to severe drought, will keep the risk level at marginal=20
for the time being. While the HREF and RRFS neighborhood=20
probabilities are fairly high for 1 and 2"+ amounts day 1, the HREF
and RRFS probabilities for 3 hour rainfall exceeding FFG values=20
remains very low, reflecting the antecedent very dry conditions.=20

...Southwest...
The closed low off the Southern CA coast is expected to move=20
little during the upcoming day 1 period. The right entrance region
of the jet streak to the east of this closed low will push=20
eastward, but continue to support uvvs enhancement in the above=20
average PW axis, 1 to 3 standard deviations above the mean, that=20
will remain in place across Southern CA into the Southwest.=20
Additional scattered convection across these areas will support=20
localized heavy amounts and isolated runoff issues. No changes were
made to the previous marginal risk area.

Oravec

Day 2
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, NORTHERN ARKANSAS, NORTHEAST OKLAHOMA AND SOUTHEAST
KANSAS...


The strengthening 850-700 mb moisture flux late day 1 over the
Southern Plains will remain anomalous day 2 as surface low=20
pressure continues to push eastward from the Southern Plains toward
the Lower Mississippi Valley. 850-700 mb moisture flux anomalies=20
are forecast to remain in the 2 to 3+ standard deviation above the=20
mean level. This will support the likelihood for the continuation=20
of the day 1 organized convection over the Southern Plains, pushing
eastward into the Lower Arkansas Valley and toward the Mid to Lower
MS Valley. There are differences with the track of the primary
surface low, resulting in north to south spread with respect to
where the max precip axis will be. WPC is favoring the more
southern qpf axes solutions, with the max axis depicted from far
eastern OK, northern OK/far southern MO into western TN. This is a
slight southward trend from previous forecasts, reflecting a
southward trend in qpf guidance. Changes to the previous slight and
25% areas were to follow the slight southward qpf axis trend,
pushing them approximately 40-60 miles farther to the south.=20=20

...Coastal Central California...=20
There is good model agreement with the nearly stationary closed=20
low off the Southern CA coast day 1 beginning to slowly move back=20
to the north on day 2 toward the Central CA coast. This slow north
movement will also allow for a northward expansion of the=20
anomalous PW values over Southern CA into coastal Central CA, with
values as high as 3-4 standard deviations above the mean. With good
model agreement on the closed low track day 2, there is also good
agreement on potential for areal average moderate precip totals,
with potential for locally heavier amount along the Central CA
coast. Isolated runoff issues are possible, especially over any=20
burn scars.=20

Oravec

Day 3
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

The mid to upper level trof moving east from the Southern Plains
day 2 will amplify day 3 as it pushes into the Lower MS Valley.
Anomalous PW and 850-700 moisture flux values will stretch across a
large area from the Lower MS Valley, and into the TN & OH Valley,=20
Central Appalachians and the Mid-Atlantic. Model consensus is for a
broad region of moderate to heavy precip in this anomalous PW and=20
850-700 mb moisture flux axis. There is a typical amount of qpf=20
spread for a day 3 time period. WPC is leaning more toward the=20
multi model ensemble qpf mean axis/NBM axis to drive our qpf and=20
excessive rainfall axis. While a large portion of the day 3 QPF and
ERO axes are currently in moderate to severe drought, there may be
overlap in qpf areas from day 3 and day 1 over the TN and OH=20
Valley regions and overlap between the day 2 and day 3 qpf axes=20
across the Lower MS Valley into the TN Valley, which will likely=20
increase soil saturations and increase stream flows. The previous=20
slight risk area was trimmed on the western edge by approximately=20
75-100 miles across far southeast MO, southern IL and southern IN=20
to better fit the latest QPF.=20


...Central California...
The slow moving closed low approaching the central CA coast late
day 2 will continue to push slowly eastward day 3 and push inland
by early Thursday morning. Similar to the day 2 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across
Central CA. Scattered convection in this anomalous PW axis will
support locally heavy rains across Central CA and isolated runoff
issues, especially across burn scar regions. Only some small
changes made to the previous marginal risk area, trimming it
westward across western NV.

...Far southeast Arizona into New Mexico...
No changes of note made to the previous marginal risk area across
this region. Scattered convection possible, with localized heavy
rain and isolated runoff issues, especially in burn scar regions.

Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5sFWbwUeOsvsKSUj3ywufAO3nYvTJ2sjZINHDiEIQdyA= o0ulud_GO1mRLAqiQWKoJ4cZHDmgs2qGRv1NNDdVnBBDDKE$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5sFWbwUeOsvsKSUj3ywufAO3nYvTJ2sjZINHDiEIQdyA= o0ulud_GO1mRLAqiQWKoJ4cZHDmgs2qGRv1NNDdVrDNVvAU$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5sFWbwUeOsvsKSUj3ywufAO3nYvTJ2sjZINHDiEIQdyA= o0ulud_GO1mRLAqiQWKoJ4cZHDmgs2qGRv1NNDdV_AEo_Gc$=20

=3D =3D =3D
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FOUS30 KWBC 221559
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1159 AM EDT Mon Sep 22 2025

Day 1
Valid 16Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTH
CENTRAL KANSAS INTO NORTH CENTRAL OKLAHOMA...

...16z update...

The marginal risk area was expanded into southern Minnesota, where
a surface boundary, 1500J/Kg+ CAPE, and 1in.+ PWATs could continue
to produce thunderstorms leading to localized flash flooding
through early this evening. The marginal risk in the Southwest was
expanded slightly into southwestern New Mexico to account for=20
wetter trends in the guidance and antecedent conditions (anomalous=20
moisture and notable instability).

Kebede

...Previous Discussion...

...Central to Southern Plains...
The latest model suite is in better agreement with the evolution
of the amplifying upper trof across the Northern to Central Rockies
day 1 and the downstream outbreak of organized convection along
and to the north of the path of the associated surface low moving
west to east from the TX Panhandle into western OK. A slight risk
area was added for the potential for organized convection along and
to the north of this low, across areas of south-central KS into
north-central OK where the low level southerly flow will be
strengthening and the corresponding 850-700 mb moisture flux
becoming anomalous, upwards to 2 to 3 standard deviations above
the mean by the end of the day 1 period. The neighborhood
probabilities are high in both the HREF and RRFS for 1 and 2"+
amounts across these areas. Additionally, both the HREF and RRFS
show a defined area of probabilities exceeding the 3 hourly FFG
values in the 0000-1200 UTC Tuesday time frame as the potentially
organized convection presses east southeastward.

...Mid to Lower Mississippi Valley into the Ohio Valley...
A broad marginal risk area was maintained in association with height
falls pushing east northeastward from the Mid Mississippi Valley
through the Ohio Valley. Well defined large scale lift in an axis
of above average PW values, 1 to 1.5+ standard deviations above the
mean, will support the likelihood of widespread moderate to heavy
precipitation in an axis from northern AR, far southeast MO, far
southeast IL, western to central KY, much of IN and OH. At the
moment the convection across these areas may be fairly progressive.
This and very low relative soil moistures, much of the area in
moderate to severe drought, will keep the risk level at marginal
for the time being. While the HREF and RRFS neighborhood
probabilities are fairly high for 1 and 2"+ amounts day 1, the HREF
and RRFS probabilities for 3 hour rainfall exceeding FFG values
remains very low, reflecting the antecedent very dry conditions.

...Southwest...
The closed low off the Southern CA coast is expected to move
little during the upcoming day 1 period. The right entrance region
of the jet streak to the east of this closed low will push
eastward, but continue to support uvvs enhancement in the above
average PW axis, 1 to 3 standard deviations above the mean, that
will remain in place across Southern CA into the Southwest.
Additional scattered convection across these areas will support
localized heavy amounts and isolated runoff issues. No changes were
made to the previous marginal risk area.

Oravec

Day 2
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, NORTHERN ARKANSAS, NORTHEAST OKLAHOMA AND SOUTHEAST
KANSAS...


The strengthening 850-700 mb moisture flux late day 1 over the
Southern Plains will remain anomalous day 2 as surface low
pressure continues to push eastward from the Southern Plains toward
the Lower Mississippi Valley. 850-700 mb moisture flux anomalies
are forecast to remain in the 2 to 3+ standard deviation above the
mean level. This will support the likelihood for the continuation
of the day 1 organized convection over the Southern Plains, pushing
eastward into the Lower Arkansas Valley and toward the Mid to Lower
MS Valley. There are differences with the track of the primary
surface low, resulting in north to south spread with respect to
where the max precip axis will be. WPC is favoring the more
southern qpf axes solutions, with the max axis depicted from far
eastern OK, northern OK/far southern MO into western TN. This is a
slight southward trend from previous forecasts, reflecting a
southward trend in qpf guidance. Changes to the previous slight and
25% areas were to follow the slight southward qpf axis trend,
pushing them approximately 40-60 miles farther to the south.

...Coastal Central California...
There is good model agreement with the nearly stationary closed
low off the Southern CA coast day 1 beginning to slowly move back
to the north on day 2 toward the Central CA coast. This slow north
movement will also allow for a northward expansion of the
anomalous PW values over Southern CA into coastal Central CA, with
values as high as 3-4 standard deviations above the mean. With good
model agreement on the closed low track day 2, there is also good
agreement on potential for areal average moderate precip totals,
with potential for locally heavier amount along the Central CA
coast. Isolated runoff issues are possible, especially over any
burn scars.

Oravec

Day 3
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

The mid to upper level trof moving east from the Southern Plains
day 2 will amplify day 3 as it pushes into the Lower MS Valley.
Anomalous PW and 850-700 moisture flux values will stretch across a
large area from the Lower MS Valley, and into the TN & OH Valley,
Central Appalachians and the Mid-Atlantic. Model consensus is for a
broad region of moderate to heavy precip in this anomalous PW and
850-700 mb moisture flux axis. There is a typical amount of qpf
spread for a day 3 time period. WPC is leaning more toward the
multi model ensemble qpf mean axis/NBM axis to drive our qpf and
excessive rainfall axis. While a large portion of the day 3 QPF and
ERO axes are currently in moderate to severe drought, there may be
overlap in qpf areas from day 3 and day 1 over the TN and OH
Valley regions and overlap between the day 2 and day 3 qpf axes
across the Lower MS Valley into the TN Valley, which will likely
increase soil saturations and increase stream flows. The previous
slight risk area was trimmed on the western edge by approximately
75-100 miles across far southeast MO, southern IL and southern IN
to better fit the latest QPF.


...Central California...
The slow moving closed low approaching the central CA coast late
day 2 will continue to push slowly eastward day 3 and push inland
by early Thursday morning. Similar to the day 2 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across
Central CA. Scattered convection in this anomalous PW axis will
support locally heavy rains across Central CA and isolated runoff
issues, especially across burn scar regions. Only some small
changes made to the previous marginal risk area, trimming it
westward across western NV.

...Far southeast Arizona into New Mexico...
No changes of note made to the previous marginal risk area across
this region. Scattered convection possible, with localized heavy
rain and isolated runoff issues, especially in burn scar regions.

Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_5OmZ-_rto3E1zVHtueb8p5dpRdXQfvsFO0GahsHNlCK= dXoOqmZCMtDac-NtjBBW6zWEBYpxCuar9UGOHI2yQdF4ISg$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_5OmZ-_rto3E1zVHtueb8p5dpRdXQfvsFO0GahsHNlCK= dXoOqmZCMtDac-NtjBBW6zWEBYpxCuar9UGOHI2ytdO7o-k$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_5OmZ-_rto3E1zVHtueb8p5dpRdXQfvsFO0GahsHNlCK= dXoOqmZCMtDac-NtjBBW6zWEBYpxCuar9UGOHI2y8bm5CXo$=20

=3D =3D =3D
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FOUS30 KWBC 221900
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Mon Sep 22 2025

Day 1
Valid 16Z Mon Sep 22 2025 - 12Z Tue Sep 23 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTH
CENTRAL KANSAS INTO NORTH CENTRAL OKLAHOMA...

...16z update...

The marginal risk area was expanded into southern Minnesota, where
a surface boundary, 1500J/Kg+ CAPE, and 1in.+ PWATs could continue
to produce thunderstorms leading to localized flash flooding
through early this evening. The marginal risk in the Southwest was
expanded slightly into southwestern New Mexico to account for
wetter trends in the guidance and antecedent conditions (anomalous
moisture and notable instability).

Kebede

...Previous Discussion...

...Central to Southern Plains...
The latest model suite is in better agreement with the evolution
of the amplifying upper trof across the Northern to Central Rockies
day 1 and the downstream outbreak of organized convection along
and to the north of the path of the associated surface low moving
west to east from the TX Panhandle into western OK. A slight risk
area was added for the potential for organized convection along and
to the north of this low, across areas of south-central KS into
north-central OK where the low level southerly flow will be
strengthening and the corresponding 850-700 mb moisture flux
becoming anomalous, upwards to 2 to 3 standard deviations above
the mean by the end of the day 1 period. The neighborhood
probabilities are high in both the HREF and RRFS for 1 and 2"+
amounts across these areas. Additionally, both the HREF and RRFS
show a defined area of probabilities exceeding the 3 hourly FFG
values in the 0000-1200 UTC Tuesday time frame as the potentially
organized convection presses east southeastward.

...Mid to Lower Mississippi Valley into the Ohio Valley...
A broad marginal risk area was maintained in association with height
falls pushing east northeastward from the Mid Mississippi Valley
through the Ohio Valley. Well defined large scale lift in an axis
of above average PW values, 1 to 1.5+ standard deviations above the
mean, will support the likelihood of widespread moderate to heavy
precipitation in an axis from northern AR, far southeast MO, far
southeast IL, western to central KY, much of IN and OH. At the
moment the convection across these areas may be fairly progressive.
This and very low relative soil moistures, much of the area in
moderate to severe drought, will keep the risk level at marginal
for the time being. While the HREF and RRFS neighborhood
probabilities are fairly high for 1 and 2"+ amounts day 1, the HREF
and RRFS probabilities for 3 hour rainfall exceeding FFG values
remains very low, reflecting the antecedent very dry conditions.

...Southwest...
The closed low off the Southern CA coast is expected to move
little during the upcoming day 1 period. The right entrance region
of the jet streak to the east of this closed low will push
eastward, but continue to support uvvs enhancement in the above
average PW axis, 1 to 3 standard deviations above the mean, that
will remain in place across Southern CA into the Southwest.
Additional scattered convection across these areas will support
localized heavy amounts and isolated runoff issues. No changes were
made to the previous marginal risk area.

Oravec

Day 2
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS MISSOURI,=20
ARKANSAS, EASTERN OKLAHOMA, WESTERN TENNESSEE, WESTERN KENTUCKY,
SOUTHERN ILLINOIS, NORTHWESTERN MISSISSIPPI AND SOUTHEAST=20
KANSAS...

...2030z update...

The marginal risk area over central/southern California was removed
from the Bay area based on drier trends in the qpf.=20

The risk areas over the Central U.S. were expanded based on high=20
12z HREF exceedence probabilities (2+ inches) across the Middle=20
Mississippi Valley. Anomalous moisture and instability along a=20
strong surface front should promote heavy rainfall. There's=20
uncertainty on where exactly the axis of maximum rainfall will=20
develop, due to the global and hires models' difficulty resolving=20
potential phasing over the Central U.S. on Tuesday.

Kebede

The strengthening 850-700 mb moisture flux late day 1 over the
Southern Plains will remain anomalous day 2 as surface low
pressure continues to push eastward from the Southern Plains toward
the Lower Mississippi Valley. 850-700 mb moisture flux anomalies
are forecast to remain in the 2 to 3+ standard deviation above the
mean level. This will support the likelihood for the continuation
of the day 1 organized convection over the Southern Plains, pushing
eastward into the Lower Arkansas Valley and toward the Mid to Lower
MS Valley. There are differences with the track of the primary
surface low, resulting in north to south spread with respect to
where the max precip axis will be. WPC is favoring the more
southern qpf axes solutions, with the max axis depicted from far
eastern OK, northern OK/far southern MO into western TN. This is a
slight southward trend from previous forecasts, reflecting a
southward trend in qpf guidance. Changes to the previous slight and
25% areas were to follow the slight southward qpf axis trend,
pushing them approximately 40-60 miles farther to the south.

...Coastal Central California...
There is good model agreement with the nearly stationary closed
low off the Southern CA coast day 1 beginning to slowly move back
to the north on day 2 toward the Central CA coast. This slow north
movement will also allow for a northward expansion of the
anomalous PW values over Southern CA into coastal Central CA, with
values as high as 3-4 standard deviations above the mean. With good
model agreement on the closed low track day 2, there is also good
agreement on potential for areal average moderate precip totals,
with potential for locally heavier amount along the Central CA
coast. Isolated runoff issues are possible, especially over any
burn scars.

Oravec

Day 3
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

...2030z update...

The marginal risk area over central/southern California was removed
from the Bay area due to recent drier qpf trends. The Marginal=20
risk area over the Southwest was confined to southern New Mexico,=20
where the tail end of the Tennessee/Ohio Valley front may produce=20
localized instances of flash flooding early on Wednesday.

The slight and marginal risk areas over the Ohio/Tennessee Valleys
were expanded to account for antecedent rainfall from today's
storms. There isn't enough of a qpf signal to overcome the severe
to extreme drought across the region so an ERO upgrade did not
occur with this cycle.

Kebede

The mid to upper level trof moving east from the Southern Plains
day 2 will amplify day 3 as it pushes into the Lower MS Valley.
Anomalous PW and 850-700 moisture flux values will stretch across a
large area from the Lower MS Valley, and into the TN & OH Valley,
Central Appalachians and the Mid-Atlantic. Model consensus is for a
broad region of moderate to heavy precip in this anomalous PW and
850-700 mb moisture flux axis. There is a typical amount of qpf
spread for a day 3 time period. WPC is leaning more toward the
multi model ensemble qpf mean axis/NBM axis to drive our qpf and
excessive rainfall axis. While a large portion of the day 3 QPF and
ERO axes are currently in moderate to severe drought, there may be
overlap in qpf areas from day 3 and day 1 over the TN and OH
Valley regions and overlap between the day 2 and day 3 qpf axes
across the Lower MS Valley into the TN Valley, which will likely
increase soil saturations and increase stream flows. The previous
slight risk area was trimmed on the western edge by approximately
75-100 miles across far southeast MO, southern IL and southern IN
to better fit the latest QPF.


...Central California...
The slow moving closed low approaching the central CA coast late
day 2 will continue to push slowly eastward day 3 and push inland
by early Thursday morning. Similar to the day 2 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across
Central CA. Scattered convection in this anomalous PW axis will
support locally heavy rains across Central CA and isolated runoff
issues, especially across burn scar regions. Only some small
changes made to the previous marginal risk area, trimming it
westward across western NV.

...Far southeast Arizona into New Mexico...
No changes of note made to the previous marginal risk area across
this region. Scattered convection possible, with localized heavy
rain and isolated runoff issues, especially in burn scar regions.

Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-LzW6GfC-4ChtFkqik62XxDvzkfb_sDCz9Sk7c_rqE9L= 7RCiU6E6MtmDVqcw0HHljvnjsKXx6MarSNLb8W6Z27HGVOo$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-LzW6GfC-4ChtFkqik62XxDvzkfb_sDCz9Sk7c_rqE9L= 7RCiU6E6MtmDVqcw0HHljvnjsKXx6MarSNLb8W6ZO0KtN7E$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-LzW6GfC-4ChtFkqik62XxDvzkfb_sDCz9Sk7c_rqE9L= 7RCiU6E6MtmDVqcw0HHljvnjsKXx6MarSNLb8W6ZKoMkinc$=20

=3D =3D =3D
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FOUS30 KWBC 230045
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
845 PM EDT Mon Sep 22 2025

Day 1
Valid 01Z Tue Sep 23 2025 - 12Z Tue Sep 23 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL IN AND NEAR KANSAS...

...Central to Southern Plains...
Thunderstorms with heavy rainfall are near the Black Hills of SD,=20
northern IA, and generally near the northern CO/KS border at the=20
time of this discussion's writing. The most organized convection=20
capable of heavy rain is forming near and north of a surface low=20
across northwest KS. The 850-700 mb moisture flux becomes=20
anomalous, upwards to 2 to 3 standard deviations above the mean by=20
Tuesday morning. The neighborhood probabilities in both the HREF=20
and RRFS for 3"+ amounts through 12z remain high enough to keep the
Slight Risk in place. With time convection moving through eastern=20
CO should merge with the northwest KS convection and form a cold=20
pool to allow the activity to drop east-southeast as it tries to=20
ride in an near an instability gradient, with a similar expectation
for the southwest SD thunderstorm cluster. Wherever cell mergers,=20 mesocyclones, or training elements occur, hourly amounts to 2.5"=20
are possible which would be most problematic in urban areas.


...Mid to Lower Mississippi Valley into the Ohio Valley...
A broad marginal risk area was maintained in association with an
upper level trough pushing east northeastward from the Mid=20
Mississippi Valley through the Ohio Valley. Well defined large=20
scale lift in an axis of above average PW values, 1 to 1.5+=20
standard deviations above the mean, will support the likelihood of=20 widespread moderate to heavy precipitation in an axis from northern
AR, far southeast MO, far southern IL, KY, and the Upper OH Valley.
Convection across these areas appears progressive. This and very=20
low relative soil moistures, much of the area in moderate to severe
drought, keep the risk level at marginal for the time being. The
guidance is unclear whether or not a heavier rain signal occurs
near the KY/TN border overnight, which bears watch. Isolated Slight
Risk impacts cannot be ruled out in that area.

Roth


Day 2
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS MISSOURI,
ARKANSAS, EASTERN OKLAHOMA, WESTERN TENNESSEE, WESTERN KENTUCKY,
SOUTHERN ILLINOIS, NORTHWESTERN MISSISSIPPI AND SOUTHEAST
KANSAS...

...2030z update...

The marginal risk area over central/southern California was removed
from the Bay area based on drier trends in the qpf.

The risk areas over the Central U.S. were expanded based on high
12z HREF exceedance probabilities (2+ inches) across the Middle
Mississippi Valley. Anomalous moisture and instability along a
strong surface front should promote heavy rainfall. There's
uncertainty on where exactly the axis of maximum rainfall will
develop, due to the global and hires models' difficulty resolving
potential phasing over the Central U.S. on Tuesday.

Kebede

The strengthening 850-700 mb moisture flux late day 1 over the
Southern Plains will remain anomalous day 2 as surface low
pressure continues to push eastward from the Southern Plains toward
the Lower Mississippi Valley. 850-700 mb moisture flux anomalies
are forecast to remain in the 2 to 3+ standard deviation above the
mean level. This will support the likelihood for the continuation
of the day 1 organized convection over the Southern Plains, pushing
eastward into the Lower Arkansas Valley and toward the Mid to Lower
MS Valley. There are differences with the track of the primary
surface low, resulting in north to south spread with respect to
where the max precip axis will be. WPC is favoring the more
southern qpf axes solutions, with the max axis depicted from far
eastern OK, northern OK/far southern MO into western TN. This is a
slight southward trend from previous forecasts, reflecting a
southward trend in qpf guidance. Changes to the previous slight and
25% areas were to follow the slight southward qpf axis trend,
pushing them approximately 40-60 miles farther to the south.

...Coastal Central California...
There is good model agreement with the nearly stationary closed
low off the Southern CA coast day 1 beginning to slowly move back
to the north on day 2 toward the Central CA coast. This slow north
movement will also allow for a northward expansion of the
anomalous PW values over Southern CA into coastal Central CA, with
values as high as 3-4 standard deviations above the mean. With good
model agreement on the closed low track day 2, there is also good
agreement on potential for areal average moderate precip totals,
with potential for locally heavier amount along the Central CA
coast. Isolated runoff issues are possible, especially over any
burn scars.

Oravec

Day 3
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

...2030z update...

The marginal risk area over central/southern California was removed
from the Bay area due to recent drier qpf trends. The Marginal
risk area over the Southwest was confined to southern New Mexico,
where the tail end of the Tennessee/Ohio Valley front may produce
localized instances of flash flooding early on Wednesday.

The slight and marginal risk areas over the Ohio/Tennessee Valleys
were expanded to account for antecedent rainfall from today's
storms. There isn't enough of a qpf signal to overcome the severe
to extreme drought across the region so an ERO upgrade did not
occur with this cycle.

Kebede

The mid to upper level trof moving east from the Southern Plains
day 2 will amplify day 3 as it pushes into the Lower MS Valley.
Anomalous PW and 850-700 moisture flux values will stretch across a
large area from the Lower MS Valley, and into the TN & OH Valley,
Central Appalachians and the Mid-Atlantic. Model consensus is for a
broad region of moderate to heavy precip in this anomalous PW and
850-700 mb moisture flux axis. There is a typical amount of qpf
spread for a day 3 time period. WPC is leaning more toward the
multi model ensemble qpf mean axis/NBM axis to drive our qpf and
excessive rainfall axis. While a large portion of the day 3 QPF and
ERO axes are currently in moderate to severe drought, there may be
overlap in qpf areas from day 3 and day 1 over the TN and OH
Valley regions and overlap between the day 2 and day 3 qpf axes
across the Lower MS Valley into the TN Valley, which will likely
increase soil saturations and increase stream flows. The previous
slight risk area was trimmed on the western edge by approximately
75-100 miles across far southeast MO, southern IL and southern IN
to better fit the latest QPF.


...Central California...
The slow moving closed low approaching the central CA coast late
day 2 will continue to push slowly eastward day 3 and push inland
by early Thursday morning. Similar to the day 2 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across
Central CA. Scattered convection in this anomalous PW axis will
support locally heavy rains across Central CA and isolated runoff
issues, especially across burn scar regions. Only some small
changes made to the previous marginal risk area, trimming it
westward across western NV.

...Far southeast Arizona into New Mexico...
No changes of note made to the previous marginal risk area across
this region. Scattered convection possible, with localized heavy
rain and isolated runoff issues, especially in burn scar regions.

Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!59bEQ8SMoGRUIJDRrYci71k3kiwLN5p7dPOklpa_wI6d= Qsa8aotAoU2BPAlv4C5Xx2XxZDMmfKgzepgc4Xqj3j9C1rY$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!59bEQ8SMoGRUIJDRrYci71k3kiwLN5p7dPOklpa_wI6d= Qsa8aotAoU2BPAlv4C5Xx2XxZDMmfKgzepgc4XqjrhrCVN8$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!59bEQ8SMoGRUIJDRrYci71k3kiwLN5p7dPOklpa_wI6d= Qsa8aotAoU2BPAlv4C5Xx2XxZDMmfKgzepgc4XqjPLgGsIo$=20

=3D =3D =3D
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FOUS30 KWBC 230759
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
359 AM EDT Tue Sep 23 2025

Day 1
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, FAR SOUTHEAST KANSAS, EASTERN OKLAHOMA, FAR NORTHEAST=20
TEXAS, ARKANSAS, WESTERN TENNESSEE, WESTERN KENTUCKY, AND SOUTHERN=20
ILLINOIS AND SOUTHERN INDIANA...

...Lower Arkansas Valley, Lower Mississippi Valley into the Lower
Ohio Valley...

The strengthening low level southerly flow/anomalous 850-700 mb=20
moisture flux that have supported organized convection over the=20
Central to Southern Plains early Tuesday will continue to support=20
the downstream push of this organized convection post 1200 UTC,=20
with these anomalous 850-700 mb moisture flux values of 2-3+=20
standard deviations above the mean moving from the eastern sections
of the Southern Plains into the Lower AR Valley, Lower MS, TN and=20
OH Valleys. There continues to be some north south spread in the=20
models with respect to the position of the max precip axis.=20
Generally, the non-CAMs are farther north and the CAMs farther=20
south. WPC continues to support the farther south qpf solutions,=20
with our day 1 risk areas drawn toward them. Overall, not a lot of=20
changes to the previous slight risk areas. We did extend the slight
risk farther east into the Lower OH Valley where there is expected
to be overlap of day 1 heavy precip with observed precip over the=20
past 24 hours. We also extended the slight risk area farther south=20
into northeast TX where several of the new 0000 UTC hi-res runs and subsequently the new HREF mean show heavy precip. Otherwise, the=20
slight and 25% areas fit well with where the HREF and RRFS=20
neighborhood probabilities are high day 1 for 2" and 3+ amounts.


...Coastal Central California...
There continues to be good model agreement with the nearly=20
stationary closed low off the Southern CA coast beginning to=20
slowly move back to the north on day 1 toward the Central CA=20
coast. This slow north movement will also allow for a northward=20
expansion of the anomalous PW values over Southern CA into coastal=20
Central CA, with values as high as 3-4 standard deviations above=20
the mean. With good model agreement on the closed low track day 1,
there is also good agreement on potential for areal average=20
moderate precip totals, with potential for locally heavier amount=20
along the Central CA coast. Isolated runoff issues are possible,=20
especially over any burn scars.

Oravec

Day 2
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

Anomalous PW and 850-700 moisture flux values will stretch across a
large area from the Lower MS Valley, and into the TN & OH Valleys,
Central Appalachians and the Mid-Atlantic, ahead of the amplifying
longwave trof stretching from the Great Lakes, southward into the
Lower MS Valley. There still is a fair amount of qpf spread with
the max axis day 2. WPC is leaning more toward the multi model
ensemble qpf mean/NBM to drive our qpf and excessive rainfall=20
axes. This will support a widespread axis of moderate to heavy
precip amounts from eastern TX into the Lower MS Valley, TN and OH
Valleys. While a large portion of the day 2 QPF and ERO axes are=20
currently in moderate to severe drought, there may be overlap in=20
qpf areas from day 2 and what has fallen over the past 24 hours=20
from eastern TN into central to eastern KY, and the Upper OH Valley
region. The previous slight risk was narrowed to better fit this=20
potential overlap areas. The marginal risk was also trimmed=20
significantly from southern L.P. of MI, IL, southeast MO and AR to
better fit the latest qpf update.

...Central California...
The slow moving closed low approaching the central CA coast late
day 1 will continue to push slowly eastward day 2 and push inland=20
by early Thursday morning. Similar to the day 1 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,=20
will persist to the east northeast of the closed low across Central
CA. Scattered convection in this anomalous PW axis will support=20
locally heavy rains across Central CA and isolated runoff issues,=20
especially across burn scar regions.

...Far southeast Arizona into New Mexico...
No changes made to the previous marginal risk area across this=20
region. Scattered convection possible, with localized heavy rain=20
and isolated runoff issues, especially in burn scar regions.

Oravec

Day 3 Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

The slow moving closed low moving inland into Central CA day 2 will
drop back to the south southeast toward Southern CA day 3. This
system will continue to have an area of anomalous PW values in the
vicinity of the upper center across Central CA into the Great
Basin. This closed low will also begin to tap anomalous PW values
over northwestern Mexico, transporting them into southeast Arizona
day 3. Model consensus is for a max precip area over Southeast
Arizona and far southwest New Mexico. The previous slight risk
across this area was only modified slightly, expanding it slightly
to the north and east to cover the model max qpf spread. Only some
minor changes to the marginal risk to the northwest of this across
northern AZ, southern NV, far southwest UT and into the central=20
Sierra. Locally heavy rains and isolated runoff issues possible=20
across these areas, especially over burn scars.=20

...Southern to Central Appalachians...
There will continue to be a broad axis of above average PW values
pushing eastward day 3 ahead of the elongated upper trof=20
stretching from the Great Lakes into the OH and TN Valleys. There=20
is a lot of qpf differences in this high PW axis, leading to low=20
confidence in where to put risk areas. Much of the eastern U.S. is=20
in drought conditions with low relative soil moisture levels. One=20
exception is over portions of the Southern to Central Appalachians
from eastern TN/far western NC/far southwest VA and eastern WV.=20
Kept the day 3 marginal confined to these areas and removed the=20
broader marginal from the previous issuance that extended north and
east into the Mid-Atlantic and southwestward to the Gulf Coast.=20


Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7nMcMn1P-s2Hl2lWZQErm_CuK4LRr5gTTWq-gfMgZt5x= 0ZRJMkjOdDFAmh9AZFPATtIf62o3pdoPsKPnJnuTkV5DYqw$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7nMcMn1P-s2Hl2lWZQErm_CuK4LRr5gTTWq-gfMgZt5x= 0ZRJMkjOdDFAmh9AZFPATtIf62o3pdoPsKPnJnuTV3apz4A$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7nMcMn1P-s2Hl2lWZQErm_CuK4LRr5gTTWq-gfMgZt5x= 0ZRJMkjOdDFAmh9AZFPATtIf62o3pdoPsKPnJnuTnEKgbE0$=20

=3D =3D =3D
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FOUS30 KWBC 230825
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
425 AM EDT Tue Sep 23 2025

Day 1
Valid 12Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, FAR SOUTHEAST KANSAS, EASTERN OKLAHOMA, FAR NORTHEAST
TEXAS, ARKANSAS, WESTERN TENNESSEE, WESTERN KENTUCKY, AND SOUTHERN
ILLINOIS AND SOUTHERN INDIANA...

...Lower Arkansas Valley, Lower Mississippi Valley into the Lower
Ohio Valley...

The strengthening low level southerly flow/anomalous 850-700 mb
moisture flux that have supported organized convection over the
Central to Southern Plains early Tuesday will continue to support
the downstream push of this organized convection post 1200 UTC,
with these anomalous 850-700 mb moisture flux values of 2-3+
standard deviations above the mean moving from the eastern sections
of the Southern Plains into the Lower AR Valley, Lower MS, TN and
OH Valleys. There continues to be some north south spread in the
models with respect to the position of the max precip axis.
Generally, the non-CAMs are farther north and the CAMs farther
south. WPC continues to support the farther south qpf solutions,
with our day 1 risk areas drawn toward them. Overall, not a lot of
changes to the previous slight risk areas. We did extend the slight
risk farther east into the Lower OH Valley where there is expected
to be overlap of day 1 heavy precip with observed precip over the
past 24 hours. We also extended the slight risk area farther south
into northeast TX where several of the new 0000 UTC hi-res runs and subsequently the new HREF mean show heavy precip. Otherwise, the
slight and 25% areas fit well with where the HREF and RRFS
neighborhood probabilities are high day 1 for 2" and 3+ amounts.


...Coastal Central California...
There continues to be good model agreement with the nearly
stationary closed low off the Southern CA coast beginning to
slowly move back to the north on day 1 toward the Central CA
coast. This slow north movement will also allow for a northward
expansion of the anomalous PW values over Southern CA into coastal
Central CA, with values as high as 3-4 standard deviations above
the mean. With good model agreement on the closed low track day 1,
there is also good agreement on potential for areal average
moderate precip totals, with potential for locally heavier amount
along the Central CA coast. Isolated runoff issues are possible,
especially over any burn scars.

Oravec

Day 2
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

Anomalous PW and 850-700 moisture flux values will stretch across a
large area from the Lower MS Valley, and into the TN & OH Valleys,
Central Appalachians and the Mid-Atlantic, ahead of the amplifying
longwave trof stretching from the Great Lakes, southward into the
Lower MS Valley. There still is a fair amount of qpf spread with
the max axis day 2. WPC is leaning more toward the multi model
ensemble qpf mean/NBM to drive our qpf and excessive rainfall
axes. This will support a widespread axis of moderate to heavy
precip amounts from eastern TX into the Lower MS Valley, TN and OH
Valleys. While a large portion of the day 2 QPF and ERO axes are
currently in moderate to severe drought, there may be overlap in
qpf areas from day 2 and what has fallen over the past 24 hours
from eastern TN into central to eastern KY, and the Upper OH Valley
region. The previous slight risk was narrowed to better fit this
potential overlap areas. The marginal risk was also trimmed
significantly from southern L.P. of MI, IL, southeast MO and AR to
better fit the latest qpf update.

...Central California...
The slow moving closed low approaching the central CA coast late
day 1 will continue to push slowly eastward day 2 and push inland
by early Thursday morning. Similar to the day 1 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across Central
CA. Scattered convection in this anomalous PW axis will support
locally heavy rains across Central CA and isolated runoff issues,
especially across burn scar regions.

...Far southeast Arizona into New Mexico...
No changes made to the previous marginal risk area across this
region. Scattered convection possible, with localized heavy rain
and isolated runoff issues, especially in burn scar regions.

Oravec

Day 3
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

The slow moving closed low moving inland into Central CA day 2 will
drop back to the south southeast toward Southern CA day 3. This
system will continue to have an area of anomalous PW values in the
vicinity of the upper center across Central CA into the Great
Basin. This closed low will also begin to tap anomalous PW values
over northwestern Mexico, transporting them into southeast Arizona
day 3. Model consensus is for a max precip area over Southeast
Arizona and far southwest New Mexico. The previous slight risk
across this area was only modified slightly, expanding it slightly
to the north and east to cover the model max qpf spread. Only some
minor changes to the marginal risk to the northwest of this across
northern AZ, southern NV, far southwest UT and into the central
Sierra. Locally heavy rains and isolated runoff issues possible
across these areas, especially over burn scars.

...Southern to Central Appalachians...
There will continue to be a broad axis of above average PW values
pushing eastward day 3 ahead of the elongated upper trof
stretching from the Great Lakes into the OH and TN Valleys. There
is a lot of qpf differences in this high PW axis, leading to low
confidence in where to put risk areas. Much of the eastern U.S. is
in drought conditions with low relative soil moisture levels. One
exception is over portions of the Southern to Central Appalachians
from eastern TN/far western NC/far southwest VA and eastern WV.
Kept the day 3 marginal confined to these areas and removed the
broader marginal from the previous issuance that extended north and
east into the Mid-Atlantic and southwestward to the Gulf Coast.


Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8Zu8ZnL1PPrE0Wx6wMUWtfPThSPOny5Dxs22C7qC2cZw= VGe2DnNYUBD8tyXBMSa6eaVoiGaStbv9ULX8CM8LV_WWBhE$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8Zu8ZnL1PPrE0Wx6wMUWtfPThSPOny5Dxs22C7qC2cZw= VGe2DnNYUBD8tyXBMSa6eaVoiGaStbv9ULX8CM8LDObXeQ4$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8Zu8ZnL1PPrE0Wx6wMUWtfPThSPOny5Dxs22C7qC2cZw= VGe2DnNYUBD8tyXBMSa6eaVoiGaStbv9ULX8CM8LEHiSYnE$=20

=3D =3D =3D
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FOUS30 KWBC 231554
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1154 AM EDT Tue Sep 23 2025

Day 1
Valid 16Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, FAR SOUTHEAST KANSAS, EASTERN OKLAHOMA, FAR NORTHEAST
TEXAS, ARKANSAS, WESTERN TENNESSEE, WESTERN KENTUCKY, AND SOUTHERN
ILLINOIS AND SOUTHERN INDIANA...

...Lower Arkansas Valley, Lower Mississippi Valley into the Lower
Ohio Valley...

16Z Update: No significant changes to the risk areas with the main
area of concern being southern Missouri, northern Arkansas, eastern
Oklahoma, and far southeast Kansas where a frontal boundary draped
across interacts with copious amounts of moisture. The 12Z HREF
probabilities align fairly well with the inherited Slight Risk=20
area with only minimal adjustments needed.=20

---previous discussion---=20

The strengthening low level southerly flow/anomalous 850-700 mb
moisture flux that have supported organized convection over the
Central to Southern Plains early Tuesday will continue to support
the downstream push of this organized convection post 1200 UTC,
with these anomalous 850-700 mb moisture flux values of 2-3+
standard deviations above the mean moving from the eastern sections
of the Southern Plains into the Lower AR Valley, Lower MS, TN and
OH Valleys. There continues to be some north south spread in the
models with respect to the position of the max precip axis.
Generally, the non-CAMs are farther north and the CAMs farther
south. WPC continues to support the farther south qpf solutions,
with our day 1 risk areas drawn toward them. Overall, not a lot of
changes to the previous slight risk areas. We did extend the slight
risk farther east into the Lower OH Valley where there is expected
to be overlap of day 1 heavy precip with observed precip over the
past 24 hours. We also extended the slight risk area farther south
into northeast TX where several of the new 0000 UTC hi-res runs and subsequently the new HREF mean show heavy precip. Otherwise, the
slight and 25% areas fit well with where the HREF and RRFS
neighborhood probabilities are high day 1 for 2" and 3+ amounts.


...Coastal Central California...
There continues to be good model agreement with the nearly
stationary closed low off the Southern CA coast beginning to
slowly move back to the north on day 1 toward the Central CA
coast. This slow north movement will also allow for a northward
expansion of the anomalous PW values over Southern CA into coastal
Central CA, with values as high as 3-4 standard deviations above
the mean. With good model agreement on the closed low track day 1,
there is also good agreement on potential for areal average
moderate precip totals, with potential for locally heavier amount
along the Central CA coast. Isolated runoff issues are possible,
especially over any burn scars.

...New Mexico...
The combination of upper level divergence bringing large scale
forcing for ascent along with an axis of slightly above normal
moisture will bring the threat of isolated to scattered
thunderstorms to the area. A Marginal Risk was introduced for the
threat of isolated flash flooding, particularly over any sensitive
areas like recent burn scars.=20

Oravec/Taylor

Day 2
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

Anomalous PW and 850-700 moisture flux values will stretch across a
large area from the Lower MS Valley, and into the TN & OH Valleys,
Central Appalachians and the Mid-Atlantic, ahead of the amplifying
longwave trof stretching from the Great Lakes, southward into the
Lower MS Valley. There still is a fair amount of qpf spread with
the max axis day 2. WPC is leaning more toward the multi model
ensemble qpf mean/NBM to drive our qpf and excessive rainfall
axes. This will support a widespread axis of moderate to heavy
precip amounts from eastern TX into the Lower MS Valley, TN and OH
Valleys. While a large portion of the day 2 QPF and ERO axes are
currently in moderate to severe drought, there may be overlap in
qpf areas from day 2 and what has fallen over the past 24 hours
from eastern TN into central to eastern KY, and the Upper OH Valley
region. The previous slight risk was narrowed to better fit this
potential overlap areas. The marginal risk was also trimmed
significantly from southern L.P. of MI, IL, southeast MO and AR to
better fit the latest qpf update.

...Central California...
The slow moving closed low approaching the central CA coast late
day 1 will continue to push slowly eastward day 2 and push inland
by early Thursday morning. Similar to the day 1 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across Central
CA. Scattered convection in this anomalous PW axis will support
locally heavy rains across Central CA and isolated runoff issues,
especially across burn scar regions.

...Far southeast Arizona into New Mexico...
No changes made to the previous marginal risk area across this
region. Scattered convection possible, with localized heavy rain
and isolated runoff issues, especially in burn scar regions.

Oravec

Day 3
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

The slow moving closed low moving inland into Central CA day 2 will
drop back to the south southeast toward Southern CA day 3. This
system will continue to have an area of anomalous PW values in the
vicinity of the upper center across Central CA into the Great
Basin. This closed low will also begin to tap anomalous PW values
over northwestern Mexico, transporting them into southeast Arizona
day 3. Model consensus is for a max precip area over Southeast
Arizona and far southwest New Mexico. The previous slight risk
across this area was only modified slightly, expanding it slightly
to the north and east to cover the model max qpf spread. Only some
minor changes to the marginal risk to the northwest of this across
northern AZ, southern NV, far southwest UT and into the central
Sierra. Locally heavy rains and isolated runoff issues possible
across these areas, especially over burn scars.

...Southern to Central Appalachians...
There will continue to be a broad axis of above average PW values
pushing eastward day 3 ahead of the elongated upper trof
stretching from the Great Lakes into the OH and TN Valleys. There
is a lot of qpf differences in this high PW axis, leading to low
confidence in where to put risk areas. Much of the eastern U.S. is
in drought conditions with low relative soil moisture levels. One
exception is over portions of the Southern to Central Appalachians
from eastern TN/far western NC/far southwest VA and eastern WV.
Kept the day 3 marginal confined to these areas and removed the
broader marginal from the previous issuance that extended north and
east into the Mid-Atlantic and southwestward to the Gulf Coast.


Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8HoWOi37BSa4wePhgYbJqOTQ5T6Zw7VBD5qIkNCFtsR3= qrGD81y0M4rM_nssEOiAkMMvayQEvR1yY6CHkD3S3sh9Itw$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8HoWOi37BSa4wePhgYbJqOTQ5T6Zw7VBD5qIkNCFtsR3= qrGD81y0M4rM_nssEOiAkMMvayQEvR1yY6CHkD3S_5foOx0$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8HoWOi37BSa4wePhgYbJqOTQ5T6Zw7VBD5qIkNCFtsR3= qrGD81y0M4rM_nssEOiAkMMvayQEvR1yY6CHkD3Sc7YbA7I$=20

=3D =3D =3D
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FOUS30 KWBC 231953
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
353 PM EDT Tue Sep 23 2025

Day 1
Valid 16Z Tue Sep 23 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHERN
MISSOURI, FAR SOUTHEAST KANSAS, EASTERN OKLAHOMA, FAR NORTHEAST
TEXAS, ARKANSAS, WESTERN TENNESSEE, WESTERN KENTUCKY, AND SOUTHERN
ILLINOIS AND SOUTHERN INDIANA...

...Lower Arkansas Valley, Lower Mississippi Valley into the Lower
Ohio Valley...

16Z Update: No significant changes to the risk areas with the main
area of concern being southern Missouri, northern Arkansas, eastern
Oklahoma, and far southeast Kansas where a frontal boundary draped
across interacts with copious amounts of moisture. The 12Z HREF
probabilities align fairly well with the inherited Slight Risk
area with only minimal adjustments needed.

---previous discussion---

The strengthening low level southerly flow/anomalous 850-700 mb
moisture flux that have supported organized convection over the
Central to Southern Plains early Tuesday will continue to support
the downstream push of this organized convection post 1200 UTC,
with these anomalous 850-700 mb moisture flux values of 2-3+
standard deviations above the mean moving from the eastern sections
of the Southern Plains into the Lower AR Valley, Lower MS, TN and
OH Valleys. There continues to be some north south spread in the
models with respect to the position of the max precip axis.
Generally, the non-CAMs are farther north and the CAMs farther
south. WPC continues to support the farther south qpf solutions,
with our day 1 risk areas drawn toward them. Overall, not a lot of
changes to the previous slight risk areas. We did extend the slight
risk farther east into the Lower OH Valley where there is expected
to be overlap of day 1 heavy precip with observed precip over the
past 24 hours. We also extended the slight risk area farther south
into northeast TX where several of the new 0000 UTC hi-res runs and subsequently the new HREF mean show heavy precip. Otherwise, the
slight and 25% areas fit well with where the HREF and RRFS
neighborhood probabilities are high day 1 for 2" and 3+ amounts.


...Coastal Central California...
There continues to be good model agreement with the nearly
stationary closed low off the Southern CA coast beginning to
slowly move back to the north on day 1 toward the Central CA
coast. This slow north movement will also allow for a northward
expansion of the anomalous PW values over Southern CA into coastal
Central CA, with values as high as 3-4 standard deviations above
the mean. With good model agreement on the closed low track day 1,
there is also good agreement on potential for areal average
moderate precip totals, with potential for locally heavier amount
along the Central CA coast. Isolated runoff issues are possible,
especially over any burn scars.

...New Mexico...
The combination of upper level divergence bringing large scale
forcing for ascent along with an axis of slightly above normal
moisture will bring the threat of isolated to scattered
thunderstorms to the area. A Marginal Risk was introduced for the
threat of isolated flash flooding, particularly over any sensitive
areas like recent burn scars.

Oravec/Taylor

Day 2
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

20Z Update:=20
No significant adjustments made to this update with the greatest
threat of intense rain rates and repeated rounds of thunderstorms
over the TN and OH Valleys into portions of the central
Appalachians. Other areas with locally higher rainfall and rain
rates are across portions of northern NJ, eastern PA, and southern
NY late in the period and then across portions of eastern TX as the
convective complexes shift southward.=20

---previous discussion---

Anomalous PW and 850-700 moisture flux values will stretch across=20
a large area from the Lower MS Valley, and into the TN & OH=20
Valleys, Central Appalachians and the Mid- Atlantic, ahead of the=20
amplifying longwave trof stretching from the Great Lakes, southward
into the Lower MS Valley. There still is a fair amount of qpf=20
spread with the max axis day 2. WPC is leaning more toward the=20
multi model ensemble qpf mean/NBM to drive our qpf and excessive=20
rainfall axes. This will support a widespread axis of moderate to=20
heavy precip amounts from eastern TX into the Lower MS Valley, TN=20
and OH Valleys. While a large portion of the day 2 QPF and ERO axes
are currently in moderate to severe drought, there may be overlap=20
in qpf areas from day 2 and what has fallen over the past 24 hours=20
from eastern TN into central to eastern KY, and the Upper OH Valley
region. The previous slight risk was narrowed to better fit this=20
potential overlap areas. The marginal risk was also trimmed=20
significantly from southern L.P. of MI, IL, southeast MO and AR to=20
better fit the latest qpf update.

...Central California...
The slow moving closed low approaching the central CA coast late
day 1 will continue to push slowly eastward day 2 and push inland
by early Thursday morning. Similar to the day 1 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across Central
CA. Scattered convection in this anomalous PW axis will support
locally heavy rains across Central CA and isolated runoff issues,
especially across burn scar regions.

...Far southeast Arizona into New Mexico...
No changes made to the previous marginal risk area across this
region. Scattered convection possible, with localized heavy rain
and isolated runoff issues, especially in burn scar regions.

Oravec

Day 3
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

The slow moving closed low moving inland into Central CA day 2 will
drop back to the south southeast toward Southern CA day 3. This
system will continue to have an area of anomalous PW values in the
vicinity of the upper center across Central CA into the Great
Basin. This closed low will also begin to tap anomalous PW values
over northwestern Mexico, transporting them into southeast Arizona
day 3. Model consensus is for a max precip area over Southeast
Arizona and far southwest New Mexico. The previous slight risk
across this area was only modified slightly, expanding it slightly
to the north and east to cover the model max qpf spread. Only some
minor changes to the marginal risk to the northwest of this across
northern AZ, southern NV, far southwest UT and into the central
Sierra. Locally heavy rains and isolated runoff issues possible
across these areas, especially over burn scars.

...Southern to Central Appalachians...
There will continue to be a broad axis of above average PW values
pushing eastward day 3 ahead of the elongated upper trof
stretching from the Great Lakes into the OH and TN Valleys. There
is a lot of qpf differences in this high PW axis, leading to low
confidence in where to put risk areas. Much of the eastern U.S. is
in drought conditions with low relative soil moisture levels. One
exception is over portions of the Southern to Central Appalachians
from eastern TN/far western NC/far southwest VA and eastern WV.
Kept the day 3 marginal confined to these areas and removed the
broader marginal from the previous issuance that extended north and
east into the Mid-Atlantic and southwestward to the Gulf Coast.


Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!45wsvkduC9LWxSdoGKkG5ccYyRNDwsbzD6jV44zf-p3W= rAmQ35ZQu2rsK6Fqo8wGVTKE0sj8OdXIV4zXuPPZVEQIqU4$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!45wsvkduC9LWxSdoGKkG5ccYyRNDwsbzD6jV44zf-p3W= rAmQ35ZQu2rsK6Fqo8wGVTKE0sj8OdXIV4zXuPPZhs_YKNQ$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!45wsvkduC9LWxSdoGKkG5ccYyRNDwsbzD6jV44zf-p3W= rAmQ35ZQu2rsK6Fqo8wGVTKE0sj8OdXIV4zXuPPZLvB3kc4$=20

=3D =3D =3D
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FOUS30 KWBC 240012
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
812 PM EDT Tue Sep 23 2025

Day 1
Valid 01Z Wed Sep 24 2025 - 12Z Wed Sep 24 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE OHIO AND MID TO LOWER MISSISSIPPI VALLEYS INTO THE ARKLATEX...

...Ohio and Mississippi Valley's into ArkLaTex...

01z Update: Surface and upper level progression over the Southern
Plains will continue through the overnight hours with large scale=20
ascent still primed to impact the Mid to Lower Mississippi Valley=20
tonight into the ArkLaTex early Wednesday morning. Thunderstorm
genesis will occur over southeast OK into western AR and move
east-southeast with the mean flow as a cold front propagates out of
OK and shoves the pattern downstream. Heavy rainfall within a
corridor of modest low to mid-level lapse rates and surface based
instability will aid in convective schema leading to locally heavy
rates between 1-2"/hr at peak intensity with the strongest cores
capable of ~3"/hr given the PWATs near 2" in place over the
aforementioned area. Copious amounts of rain and flash flood
signals were prevalent earlier in the D1 period, and that threat
will continue its migration south along and ahead of the cold
front. This was more than enough to favor a general maintenance of
the SLGT risk from prior forecast, but did scale back on the
northern and western flank of the risk due to the heavy rainfall
prospects likely done with the frontal approach imminent, and/or
loss of favored ascent.=20

The threat for scattered heavy rainfall expands eastward into the=20
Southern Ohio, and Tennessee Valley's as a quasi- stationary front=20
bisects the area from the Ozarks into the western reaches of the=20
Ohio Valley. Expectation is for smaller mid- level perturbations to
ripple eastward along the front enacting focused ascent within the
boundary confines which could spell for periods of locally heavy=20
rain with some training potential in-of the front. Signal is not=20
nearly as prolific as upstream over the Mississippi Valley, mainly=20
due to the lower instability forecast over the area. That said,=20
lower FFG's add favor to a threat overnight as any cell >1"/hr will
have the capability to induce some flash flood prospects. As a=20
result, have maintained the previous SLGT risk forecast over the=20
area with some minor expansion to the east given recent hi-res
trends.=20

...Coastal Central California...

01z Update: Primary threat for flash flooding this evening across
CA will be situated within any remnant burn scars that exhibit
those isolated pockets of much lower FFG's that would favor a
better threat for flash flooding. The setup was forecast to occur
this evening, so there was no reason to deviate from continuity.
The previous MRGL was maintained with no changes.=20

...Kansas...=20

01z Update: Shortwave ejection out of the Front Range will slowly
migrate eastward with a threat of heavy rain from convection
situated in-of the axis of a weak nocturnal LLJ converging with a
residual quasi-stationary front over northwest KS. The threat is
very isolated in nature, but hi-res continues to depict a small
axis of heavy rain potential from the CO/KS border near Goodland
down into Dodge City during the evening. The threat remains within
the lower bounds of the MRGL risk threshold, but still has merit,
so maintained continuity over the region and removed the risk
downstream over central and eastern KS as the threat there has
ended.=20

Kleebauer


Day 2
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

20Z Update:
No significant adjustments made to this update with the greatest
threat of intense rain rates and repeated rounds of thunderstorms
over the TN and OH Valleys into portions of the central
Appalachians. Other areas with locally higher rainfall and rain
rates are across portions of northern NJ, eastern PA, and southern
NY late in the period and then across portions of eastern TX as the
convective complexes shift southward.

---previous discussion---

Anomalous PW and 850-700 moisture flux values will stretch across
a large area from the Lower MS Valley, and into the TN & OH
Valleys, Central Appalachians and the Mid- Atlantic, ahead of the
amplifying longwave trof stretching from the Great Lakes, southward
into the Lower MS Valley. There still is a fair amount of qpf
spread with the max axis day 2. WPC is leaning more toward the
multi model ensemble qpf mean/NBM to drive our qpf and excessive
rainfall axes. This will support a widespread axis of moderate to
heavy precip amounts from eastern TX into the Lower MS Valley, TN
and OH Valleys. While a large portion of the day 2 QPF and ERO axes
are currently in moderate to severe drought, there may be overlap
in qpf areas from day 2 and what has fallen over the past 24 hours
from eastern TN into central to eastern KY, and the Upper OH Valley
region. The previous slight risk was narrowed to better fit this
potential overlap areas. The marginal risk was also trimmed
significantly from southern L.P. of MI, IL, southeast MO and AR to
better fit the latest qpf update.

...Central California...
The slow moving closed low approaching the central CA coast late
day 1 will continue to push slowly eastward day 2 and push inland
by early Thursday morning. Similar to the day 1 period, an axis of
anomalous PW values, 2 to 3 standard deviations above the mean,
will persist to the east northeast of the closed low across Central
CA. Scattered convection in this anomalous PW axis will support
locally heavy rains across Central CA and isolated runoff issues,
especially across burn scar regions.

...Far southeast Arizona into New Mexico...
No changes made to the previous marginal risk area across this
region. Scattered convection possible, with localized heavy rain
and isolated runoff issues, especially in burn scar regions.

Oravec

Day 3
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

The slow moving closed low moving inland into Central CA day 2 will
drop back to the south southeast toward Southern CA day 3. This
system will continue to have an area of anomalous PW values in the
vicinity of the upper center across Central CA into the Great
Basin. This closed low will also begin to tap anomalous PW values
over northwestern Mexico, transporting them into southeast Arizona
day 3. Model consensus is for a max precip area over Southeast
Arizona and far southwest New Mexico. The previous slight risk
across this area was only modified slightly, expanding it slightly
to the north and east to cover the model max qpf spread. Only some
minor changes to the marginal risk to the northwest of this across
northern AZ, southern NV, far southwest UT and into the central
Sierra. Locally heavy rains and isolated runoff issues possible
across these areas, especially over burn scars.

...Southern to Central Appalachians...
There will continue to be a broad axis of above average PW values
pushing eastward day 3 ahead of the elongated upper trof
stretching from the Great Lakes into the OH and TN Valleys. There
is a lot of qpf differences in this high PW axis, leading to low
confidence in where to put risk areas. Much of the eastern U.S. is
in drought conditions with low relative soil moisture levels. One
exception is over portions of the Southern to Central Appalachians
from eastern TN/far western NC/far southwest VA and eastern WV.
Kept the day 3 marginal confined to these areas and removed the
broader marginal from the previous issuance that extended north and
east into the Mid-Atlantic and southwestward to the Gulf Coast.


Oravec

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4p_bm-eNh2_g7NQ8dqT5VqOJxwnnOneinigyAjdiEhEF= 8Vp84CGLuHD8UTziNOgK9SJGyrhcRLuNlIMz9JDU5Sc5mvY$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4p_bm-eNh2_g7NQ8dqT5VqOJxwnnOneinigyAjdiEhEF= 8Vp84CGLuHD8UTziNOgK9SJGyrhcRLuNlIMz9JDUFyNPMwI$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4p_bm-eNh2_g7NQ8dqT5VqOJxwnnOneinigyAjdiEhEF= 8Vp84CGLuHD8UTziNOgK9SJGyrhcRLuNlIMz9JDUFxuMuKM$=20

=3D =3D =3D
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FOUS30 KWBC 240831
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
431 AM EDT Wed Sep 24 2025

Day 1
Valid 12Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

...Southern Plains to the Central and Southern Appalachians...

Overall, no large-scale changes to the previous outlook areas,
maintaining a broad Marginal Risk that extends from portions of
central and southern Texas to the southern and central=20
Appalachians, with an embedded Slight Risk centered over parts of=20
the Ohio and Tennessee valleys.=20

Composite radar this morning shows widespread showers and storms=20
extending from the Ohio Valley back into the southern Plains. The=20
overnight CAMs indicate that ongoing storms along the far eastern=20 Oklahoma-Texas border into southern Arkansas will remain organized
into the late morning as the drift slowly south, with training=20
storms likely to produce heavy amounts across portions of=20
northeastern Texas and northwestern Louisiana. Supported by=20
shortwave energy moving through the base of a broader-scale=20 positively-tilted upper trough and PWs at or above 2 inches, HREF=20 probabilities indicate locally heavy amounts exceeding 3 inches are
likely. However, dry soil conditions, reflected by high FFGs, are=20
expected to limit the threat for widespread flooding concerns.

As energy continues to move through the base of the upper trough,
an area of low pressure is expected to become better organized and
track northeast through the Ohio Valley beginning later this
afternoon and continuing into the overnight. Deep southwesterly
flow ahead of the wave will support increasing moisture, with PW
anomalies increasing to over 2 std dev above normal per the GFS.
Given the ongoing rains and relatively wetter soil conditions
(lower FFGs), a Slight Risk extending from far northern Alabama to
far southern Ohio and western West Virginia was maintained. HREF=20 probabilities indicate that amounts of 1-2 inches will be common,=20
with locally heavier amounts over 3 inches possible within the=20
Slight Risk area.

In the wake of the low, showers and storms producing heavier rates
are expected along the trailing front as it sinks south through=20
the lower Mississippi Valley and along the upper Texas coast back=20
into South Texas. Here too, the HREF is indicating locally heavy=20
amounts over 3 inches are likely. But similar to areas to the=20
north, higher FFGs suggest flooding issues will be mostly contained
to vulnerable areas, including urbanized centers.

...Northeast...

The general consensus of the CAMs shows an area of showers and
storms moving northeast well in advance of the system over the Ohio
Valley. Supported by deepening moisture along a slow-moving
boundary and increasing mid-to-upper level forcing, showers and
storms will advance northeast across Pennsylvania, with repeating
storms potentially resulting in locally heavy amounts from
northeastern Pennsylvania into the lower Hudson Valley/NYC area. A
A Marginal Risk was maintained for areas where the HREF shows=20
higher probabilities for amounts over 2 inches and where FFGs are=20
relatively lower.

...Southeastern Lower Michigan...

An upper low closing off this morning is expected to remain
centered over Lower Michigan into Thursday morning. Showers and
storms are likely to develop east of the center, with relatively
deeper moisture wrapping into the system raising the potential for
locally heavy rainfall rates. A small Marginal Risk was=20
introduced, highlighting the area where the HREF shows high=20
probabilities for accumulations exceeding 2 inches.

...Central California...

A slow-moving upper low currently offshore will drift north and
begin moving inland Thursday morning. With anomalous moisture
remaining in place (2.5-3 std dev above normal), locally heavy
amounts will remain possible. Reflecting the high HREF
probabilities for amounts over an inch, a Marginal Risk was
maintained along the central California Coast from the Monterey=20
Bay south and along the adjacent mountains.=20

Pereira


Day 2
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

...Southwest to Sierra Nevada...

After moving inland early Thursday, the closed low over central
California is forecast to drop south into southern California by
early Friday. With ample moisture remaining in place (2-3 std
dev above normal) near and east of the upper center, locally heavy
amounts are possible from the Sierra Nevada east into southern=20
Nevada and southwestern Utah.

As the center drops south, increasing southerly flow east of the
low will draw deeper moisture up from Mexico, fueling widespread
shower and thunderstorm coverage, especially across southeastern
and central Arizona into southwestern New Mexico. A Slight Risk=20
was maintained across this area where PWs are forecast to increase=20
to 1-2 standard deviations above normal by the afternoon.

...Northeast...

Unsettled weather developing Day 1 is forecast to continue into=20
Thursday as showers and storms continue to develop ahead of the=20
system lifting out of the Ohio Valley into the Northeast.=20
Strengthening southwesterly flow along the Mid Atlantic coast into=20
the Northeast will support deepening moisture (PWs increasing to ~2
inches) and an increasing threat for heavy rainfall rates. A=20
Marginal Risk was maintained from northern New Jersey into southern
New England, where HREF probabilities indicate that localized=20
amounts over 3 inches are possible late Thursday morning into the=20
afternoon.

...Southern Appalachians...

The consensus of the latest guidance indicates that showers and
storms developing along and ahead of the cold front trailing the=20
low moving through the Northeast will be generally progressive.=20
With widespread heavy amounts not expected and FFGs high, the=20
previous Marginal Risk was removed from much of the Mid Atlantic.=20
However, some models do show the potential for training storms to=20
produce some localized heavy amounts (2+ inches) across parts of=20
the southern Appalachians, where a small Marginal Risk was=20
maintained.

Pereira


Day 3
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...

A second day of numerous showers and storms is expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. The upper low setting into southern
California the previous period is expected to move little this day,
remaining centered near the California/Mexico border. This will
help to maintain anomalous moisture across the region, fueling
widespread shower and thunderstorm coverage during the afternoon=20
and evening hours. A Slight Risk, with a footprint similar to the=20
Day 2 area, was maintained for Day 3 across parts of Arizona and=20
New Mexico.

...Southeast...

A boundary will remain in place across the Southeast as an upper
trough evolves into a closed low that is forecast to linger beyond
the period. Moisture and energy lifting ahead of the closing system
will support periods of shower and storms. While the guidance at
this point is not signaling any widespread heavy amounts, the
pattern does lend itself to at least the threat for locally heavy
amounts, which may raise at least isolated flooding concerns.

Pereira

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5vA739x67VpnfVraAik3IwQLSuWXLa9vminnKBPVMd88= _4ip2yq-4cSfT_dtRHVGrOOe9KqZkZf6iCg6bJT_HUWuYcM$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5vA739x67VpnfVraAik3IwQLSuWXLa9vminnKBPVMd88= _4ip2yq-4cSfT_dtRHVGrOOe9KqZkZf6iCg6bJT_2G4rUvQ$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5vA739x67VpnfVraAik3IwQLSuWXLa9vminnKBPVMd88= _4ip2yq-4cSfT_dtRHVGrOOe9KqZkZf6iCg6bJT_5YHAnno$=20

=3D =3D =3D
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FOUS30 KWBC 241557
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1157 AM EDT Wed Sep 24 2025

Day 1
Valid 16Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS...

...Southern Plains to the Central and Southern Appalachians...

Overall, no large-scale changes to the previous outlook areas,
maintaining a broad Marginal Risk that extends from portions of
central and southern Texas to the southern and central
Appalachians, with an embedded Slight Risk centered over parts of
the Ohio and Tennessee valleys.

Composite radar this morning shows widespread showers and storms
extending from the Ohio Valley back into the southern Plains. The
overnight CAMs indicate that ongoing storms along the far eastern Oklahoma-Texas border into southern Arkansas will remain organized
into the late morning as the drift slowly south, with training
storms likely to produce heavy amounts across portions of
northeastern Texas and northwestern Louisiana. Supported by
shortwave energy moving through the base of a broader-scale
positively-tilted upper trough and PWs at or above 2 inches, HREF
probabilities indicate locally heavy amounts exceeding 3 inches are
likely. However, dry soil conditions, reflected by high FFGs, are
expected to limit the threat for widespread flooding concerns.

As energy continues to move through the base of the upper trough,
an area of low pressure is expected to become better organized and
track northeast through the Ohio Valley beginning later this
afternoon and continuing into the overnight. Deep southwesterly
flow ahead of the wave will support increasing moisture, with PW
anomalies increasing to over 2 std dev above normal per the GFS.
Given the ongoing rains and relatively wetter soil conditions
(lower FFGs), a Slight Risk extending from far northern Alabama to
far southern Ohio and western West Virginia was maintained. HREF
probabilities indicate that amounts of 1-2 inches will be common,
with locally heavier amounts over 3 inches possible within the
Slight Risk area.

In the wake of the low, showers and storms producing heavier rates
are expected along the trailing front as it sinks south through
the lower Mississippi Valley and along the upper Texas coast back
into South Texas. Here too, the HREF is indicating locally heavy
amounts over 3 inches are likely. But similar to areas to the
north, higher FFGs suggest flooding issues will be mostly contained
to vulnerable areas, including urbanized centers.

...Northeast...

The general consensus of the CAMs shows an area of showers and
storms moving northeast well in advance of the system over the Ohio
Valley. Supported by deepening moisture along a slow-moving
boundary and increasing mid-to-upper level forcing, showers and
storms will advance northeast across Pennsylvania, with repeating
storms potentially resulting in locally heavy amounts from
northeastern Pennsylvania into the lower Hudson Valley/NYC area. A
A Marginal Risk was maintained for areas where the HREF shows
higher probabilities for amounts over 2 inches and where FFGs are
relatively lower.

...Southeastern Lower Michigan...

An upper low closing off this morning is expected to remain
centered over Lower Michigan into Thursday morning. Showers and
storms are likely to develop east of the center, with relatively
deeper moisture wrapping into the system raising the potential for
locally heavy rainfall rates. A small Marginal Risk was
introduced, highlighting the area where the HREF shows high
probabilities for accumulations exceeding 2 inches.

...Central California...

A slow-moving upper low currently offshore will drift north and
begin moving inland Thursday morning. With anomalous moisture
remaining in place (2.5-3 std dev above normal), locally heavy
amounts will remain possible. Reflecting the high HREF
probabilities for amounts over an inch, a Marginal Risk was
maintained along the central California Coast from the Monterey
Bay south and along the adjacent mountains.

Pereira


Day 2
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

...Southwest to Sierra Nevada...

After moving inland early Thursday, the closed low over central
California is forecast to drop south into southern California by
early Friday. With ample moisture remaining in place (2-3 std
dev above normal) near and east of the upper center, locally heavy
amounts are possible from the Sierra Nevada east into southern
Nevada and southwestern Utah.

As the center drops south, increasing southerly flow east of the
low will draw deeper moisture up from Mexico, fueling widespread
shower and thunderstorm coverage, especially across southeastern
and central Arizona into southwestern New Mexico. A Slight Risk
was maintained across this area where PWs are forecast to increase
to 1-2 standard deviations above normal by the afternoon.

...Northeast...

Unsettled weather developing Day 1 is forecast to continue into
Thursday as showers and storms continue to develop ahead of the
system lifting out of the Ohio Valley into the Northeast.
Strengthening southwesterly flow along the Mid Atlantic coast into
the Northeast will support deepening moisture (PWs increasing to ~2
inches) and an increasing threat for heavy rainfall rates. A
Marginal Risk was maintained from northern New Jersey into southern
New England, where HREF probabilities indicate that localized
amounts over 3 inches are possible late Thursday morning into the
afternoon.

...Southern Appalachians...

The consensus of the latest guidance indicates that showers and
storms developing along and ahead of the cold front trailing the
low moving through the Northeast will be generally progressive.
With widespread heavy amounts not expected and FFGs high, the
previous Marginal Risk was removed from much of the Mid Atlantic.
However, some models do show the potential for training storms to
produce some localized heavy amounts (2+ inches) across parts of
the southern Appalachians, where a small Marginal Risk was
maintained.

Pereira


Day 3
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...

A second day of numerous showers and storms is expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. The upper low setting into southern
California the previous period is expected to move little this day,
remaining centered near the California/Mexico border. This will
help to maintain anomalous moisture across the region, fueling
widespread shower and thunderstorm coverage during the afternoon
and evening hours. A Slight Risk, with a footprint similar to the
Day 2 area, was maintained for Day 3 across parts of Arizona and
New Mexico.

...Southeast...

A boundary will remain in place across the Southeast as an upper
trough evolves into a closed low that is forecast to linger beyond
the period. Moisture and energy lifting ahead of the closing system
will support periods of shower and storms. While the guidance at
this point is not signaling any widespread heavy amounts, the
pattern does lend itself to at least the threat for locally heavy
amounts, which may raise at least isolated flooding concerns.

Pereira

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!85yS_gHHnzXqyxgQt_fhXScJ1XWXrinD7B4VtLMbPcW7= L0HP2NNaLBjOQa_ks8Eqm1iNmQJvLmF3pikwl2cyj6Kwtl4$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!85yS_gHHnzXqyxgQt_fhXScJ1XWXrinD7B4VtLMbPcW7= L0HP2NNaLBjOQa_ks8Eqm1iNmQJvLmF3pikwl2cy6tLcAT0$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!85yS_gHHnzXqyxgQt_fhXScJ1XWXrinD7B4VtLMbPcW7= L0HP2NNaLBjOQa_ks8Eqm1iNmQJvLmF3pikwl2cyM4jMSdY$=20

=3D =3D =3D
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FOUS30 KWBC 241626
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1226 PM EDT Wed Sep 24 2025

Day 1
Valid 16Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS, ALONG WITH PARTS OF THE WESTERN
GULF COAST INTO THE LOWER MISSISSIPPI VALLEY...

...Southern Plains to the Central and Southern Appalachians...

...1600 UTC Update...
Based on the rainfall that has already fallen, along with the 12Z
CAM guidance (including HREF probabilistic suite), have expanded
the Slight Risk area to include western TN and more of the TN=20
Valley (northeast MS, northern AL, and northwest GA). This=20
expansion picks up on the enhanced HREF probabilities of 2+ inch/hr
rainfall rates, along with the higher probs of exceeding 5.00"=20
(isolated areas near 30 percent) through the remainder of the day 1
period (through 12Z Thu).

Meanwhile, have also expanded the Slight Risk area across parts of
the Lower MS Valley to eastern TX and along much of the TX coast.
This was a fairly sizable shift from the previous forecast, and=20
was based largely from the latest (12Z) CAM guidance as well as=20 observational trends. While the coverage may be more isolated than=20 scattered, the thermodynamic parameters (high TPWs around 2" and=20
mixed-layer CAPEs of 2000-2500 J/Kg) are optimal in maximizing the=20 precipitation efficiency. The latest CAMs, especially HREF=20
probabilities, continue to show the potential for a "high-end"=20
heavy rainfall event, again even if more isolated than scattered.=20
Certainly enough to justify the more enhanced ERO risk (Slight vs.=20 Marginal). Within this expanded Slight Risk area, the 12Z HREF=20
indicated probabilities have climbed to 40-50% in areas from=20
northeast TX into southern AR-northern LA. In addition, 5+ inch=20 probabilities are now 50-60%+ across a small portion of south-=20
central TX.=20

...Previous discussion...

Composite radar this morning shows widespread showers and storms
extending from the Ohio Valley back into the southern Plains. The
overnight CAMs indicate that ongoing storms along the far eastern Oklahoma-Texas border into southern Arkansas will remain organized
into the late morning as the drift slowly south, with training
storms likely to produce heavy amounts across portions of
northeastern Texas and northwestern Louisiana. Supported by
shortwave energy moving through the base of a broader-scale
positively-tilted upper trough and PWs at or above 2 inches, HREF
probabilities indicate locally heavy amounts exceeding 3 inches are
likely. However, dry soil conditions, reflected by high FFGs, are
expected to limit the threat for widespread flooding concerns.

As energy continues to move through the base of the upper trough,
an area of low pressure is expected to become better organized and
track northeast through the Ohio Valley beginning later this
afternoon and continuing into the overnight. Deep southwesterly
flow ahead of the wave will support increasing moisture, with PW
anomalies increasing to over 2 std dev above normal per the GFS.
Given the ongoing rains and relatively wetter soil conditions
(lower FFGs), a Slight Risk extending from far northern Alabama to
far southern Ohio and western West Virginia was maintained. HREF
probabilities indicate that amounts of 1-2 inches will be common,
with locally heavier amounts over 3 inches possible within the
Slight Risk area.

In the wake of the low, showers and storms producing heavier rates
are expected along the trailing front as it sinks south through
the lower Mississippi Valley and along the upper Texas coast back
into South Texas. Here too, the HREF is indicating locally heavy
amounts over 3 inches are likely. But similar to areas to the
north, higher FFGs suggest flooding issues will be mostly contained
to vulnerable areas, including urbanized centers.

...Northeast...

The general consensus of the CAMs shows an area of showers and
storms moving northeast well in advance of the system over the Ohio
Valley. Supported by deepening moisture along a slow-moving
boundary and increasing mid-to-upper level forcing, showers and
storms will advance northeast across Pennsylvania, with repeating
storms potentially resulting in locally heavy amounts from
northeastern Pennsylvania into the Hudson Valley, parts of far
western New England, and the NYC area. A A Marginal Risk was=20
maintained for areas where the HREF shows higher probabilities for=20
amounts over 2 inches and where FFGs are relatively lower.

...Central California...

A slow-moving upper low currently offshore will drift north and
begin moving inland Thursday morning. With anomalous moisture
remaining in place (2.5-3 std dev above normal), locally heavy
amounts will remain possible. Reflecting the high HREF
probabilities for amounts over an inch, a Marginal Risk was
maintained along the central California Coast from the Monterey
Bay south and along the adjacent mountains.

Hurley/Pereira


Day 2
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

...Southwest to Sierra Nevada...

After moving inland early Thursday, the closed low over central
California is forecast to drop south into southern California by
early Friday. With ample moisture remaining in place (2-3 std
dev above normal) near and east of the upper center, locally heavy
amounts are possible from the Sierra Nevada east into southern
Nevada and southwestern Utah.

As the center drops south, increasing southerly flow east of the
low will draw deeper moisture up from Mexico, fueling widespread
shower and thunderstorm coverage, especially across southeastern
and central Arizona into southwestern New Mexico. A Slight Risk
was maintained across this area where PWs are forecast to increase
to 1-2 standard deviations above normal by the afternoon.

...Northeast...

Unsettled weather developing Day 1 is forecast to continue into
Thursday as showers and storms continue to develop ahead of the
system lifting out of the Ohio Valley into the Northeast.
Strengthening southwesterly flow along the Mid Atlantic coast into
the Northeast will support deepening moisture (PWs increasing to ~2
inches) and an increasing threat for heavy rainfall rates. A
Marginal Risk was maintained from northern New Jersey into southern
New England, where HREF probabilities indicate that localized
amounts over 3 inches are possible late Thursday morning into the
afternoon.

...Southern Appalachians...

The consensus of the latest guidance indicates that showers and
storms developing along and ahead of the cold front trailing the
low moving through the Northeast will be generally progressive.
With widespread heavy amounts not expected and FFGs high, the
previous Marginal Risk was removed from much of the Mid Atlantic.
However, some models do show the potential for training storms to
produce some localized heavy amounts (2+ inches) across parts of
the southern Appalachians, where a small Marginal Risk was
maintained.

Pereira


Day 3
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...

A second day of numerous showers and storms is expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. The upper low setting into southern
California the previous period is expected to move little this day,
remaining centered near the California/Mexico border. This will
help to maintain anomalous moisture across the region, fueling
widespread shower and thunderstorm coverage during the afternoon
and evening hours. A Slight Risk, with a footprint similar to the
Day 2 area, was maintained for Day 3 across parts of Arizona and
New Mexico.

...Southeast...

A boundary will remain in place across the Southeast as an upper
trough evolves into a closed low that is forecast to linger beyond
the period. Moisture and energy lifting ahead of the closing system
will support periods of shower and storms. While the guidance at
this point is not signaling any widespread heavy amounts, the
pattern does lend itself to at least the threat for locally heavy
amounts, which may raise at least isolated flooding concerns.

Pereira

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6IOgtnsNUs9Vul3LxDZK_cWnJhfkyR2n3cL3tfG8rVqf= do8bGqz74mG8lVEoGDXNcV-j6tkRha585SaABISHZInaJms$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6IOgtnsNUs9Vul3LxDZK_cWnJhfkyR2n3cL3tfG8rVqf= do8bGqz74mG8lVEoGDXNcV-j6tkRha585SaABISHl6XUVCA$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6IOgtnsNUs9Vul3LxDZK_cWnJhfkyR2n3cL3tfG8rVqf= do8bGqz74mG8lVEoGDXNcV-j6tkRha585SaABISHYu7MWmc$=20

=3D =3D =3D
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FOUS30 KWBC 241902
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
302 PM EDT Wed Sep 24 2025

Day 1
Valid 16Z Wed Sep 24 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE
TENNESSEE AND OHIO VALLEY REGIONS, ALONG WITH PARTS OF THE WESTERN
GULF COAST INTO THE LOWER MISSISSIPPI VALLEY...

...Southern Plains to the Central and Southern Appalachians...

...1600 UTC Update...

Based on the rainfall that has already fallen, along with the 12Z
CAM guidance (including HREF probabilistic suite), have expanded
the Slight Risk area to include western TN and more of the TN
Valley (northeast MS, northern AL, and northwest GA). This
expansion picks up on the enhanced HREF probabilities of 2+ inch/hr
rainfall rates, along with the higher probs of exceeding 5.00"
(isolated areas near 30 percent) through the remainder of the day 1
period (through 12Z Thu).

Meanwhile, have also expanded the Slight Risk area across parts of
the Lower MS Valley to eastern TX and along much of the TX coast.
This was a fairly sizable shift from the previous forecast, and
was based largely from the latest (12Z) CAM guidance as well as
observational trends. While the coverage may be more isolated than
scattered, the thermodynamic parameters (high TPWs around 2" and
mixed-layer CAPEs of 2000-2500 J/Kg) are optimal in maximizing the precipitation efficiency. The latest CAMs, especially HREF
probabilities, continue to show the potential for a "high-end"
heavy rainfall event, again even if more isolated than scattered.
Certainly enough to justify the more enhanced ERO risk (Slight vs.
Marginal). Within this expanded Slight Risk area, the 12Z HREF
indicated probabilities have climbed to 40-50% in areas from
northeast TX into southern AR-northern LA. In addition, 5+ inch
probabilities are now 50-60%+ across a small portion of south-
central TX.

...Previous discussion...

Composite radar this morning shows widespread showers and storms
extending from the Ohio Valley back into the southern Plains. The
overnight CAMs indicate that ongoing storms along the far eastern Oklahoma-Texas border into southern Arkansas will remain organized
into the late morning as the drift slowly south, with training
storms likely to produce heavy amounts across portions of
northeastern Texas and northwestern Louisiana. Supported by
shortwave energy moving through the base of a broader-scale
positively-tilted upper trough and PWs at or above 2 inches, HREF
probabilities indicate locally heavy amounts exceeding 3 inches are
likely. However, dry soil conditions, reflected by high FFGs, are
expected to limit the threat for widespread flooding concerns.

As energy continues to move through the base of the upper trough,
an area of low pressure is expected to become better organized and
track northeast through the Ohio Valley beginning later this
afternoon and continuing into the overnight. Deep southwesterly
flow ahead of the wave will support increasing moisture, with PW
anomalies increasing to over 2 std dev above normal per the GFS.
Given the ongoing rains and relatively wetter soil conditions
(lower FFGs), a Slight Risk extending from far northern Alabama to
far southern Ohio and western West Virginia was maintained. HREF
probabilities indicate that amounts of 1-2 inches will be common,
with locally heavier amounts over 3 inches possible within the
Slight Risk area.

In the wake of the low, showers and storms producing heavier rates
are expected along the trailing front as it sinks south through
the lower Mississippi Valley and along the upper Texas coast back
into South Texas. Here too, the HREF is indicating locally heavy
amounts over 3 inches are likely. But similar to areas to the
north, higher FFGs suggest flooding issues will be mostly contained
to vulnerable areas, including urbanized centers.

...Northeast...

The general consensus of the CAMs shows an area of showers and
storms moving northeast well in advance of the system over the Ohio
Valley. Supported by deepening moisture along a slow-moving
boundary and increasing mid-to-upper level forcing, showers and
storms will advance northeast across Pennsylvania, with repeating
storms potentially resulting in locally heavy amounts from
northeastern Pennsylvania into the Hudson Valley, parts of far
western New England, and the NYC area. A A Marginal Risk was
maintained for areas where the HREF shows higher probabilities for
amounts over 2 inches and where FFGs are relatively lower.

...Central California...

A slow-moving upper low currently offshore will drift north and
begin moving inland Thursday morning. With anomalous moisture
remaining in place (2.5-3 std dev above normal), locally heavy
amounts will remain possible. Reflecting the high HREF
probabilities for amounts over an inch, a Marginal Risk was
maintained along the central California Coast from the Monterey
Bay south and along the adjacent mountains.

Hurley/Pereira


Day 2
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

...Southwest to Sierra Nevada...

After moving inland early Thursday, the closed low over central
California is forecast to drop south into southern California by
early Friday. With ample moisture remaining in place (2-3 std
dev above normal) near and east of the upper center, locally heavy
amounts are possible from the Sierra Nevada east into southern
Nevada and southwestern Utah.

As the center drops south, increasing southerly flow east of the
low will draw deeper moisture up from Mexico, fueling widespread
shower and thunderstorm coverage, especially across southeastern
and central Arizona into southwestern New Mexico. A Slight Risk
was maintained across this area where PWs are forecast to increase
to 1-2 standard deviations above normal by the afternoon.

...Northeast...

Unsettled weather developing Day 1 is forecast to continue into
Thursday as showers and storms continue to develop ahead of the
system lifting out of the Ohio Valley into the Northeast.
Strengthening southwesterly flow along the Mid Atlantic coast into
the Northeast will support deepening moisture (PWs increasing to ~2
inches) and an increasing threat for heavy rainfall rates. A
Marginal Risk was maintained from northern New Jersey into southern
New England, where HREF probabilities indicate that localized
amounts over 3 inches are possible late Thursday morning into the
afternoon.

...Southern Appalachians into parts of the Southeast and Eastern=20
Gulf Coast...

...2000 UTC Update...

Amplifying mid-upper trough digging into the northwest and north-=20
central Gulf Thu-Thu night will slow the eastward progression of=20
the surface cold front and thus favorable pre-frontal buoyant=20
airmass (ribbon of higher TPW and deep-layer instability). More=20
protracted period of favorable low-level moisture transport ahead=20
of the upper trough/surface front. 12Z HREF probabilities depict
this idea well, with several hours of spotty areas with enhanced=20
probs for 1-2+ in/hr rainfall rates. Therefore, supported by the
latest CSU UFVS-verified ERO First-Guess field, have expanded the
Marginal Risk south to the MS-AL-western FL Panhandle Gulf Coast.=20


...Previous Discussion...

The consensus of the latest guidance indicates that showers and
storms developing along and ahead of the cold front trailing the
low moving through the Northeast will be generally progressive.
With widespread heavy amounts not expected and FFGs high, the
previous Marginal Risk was removed from much of the Mid Atlantic.
However, some models do show the potential for training storms to
produce some localized heavy amounts (2+ inches) across parts of
the southern Appalachians, where a small Marginal Risk was
maintained.

Hurley/Pereira


Day 3
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...

A second day of numerous showers and storms is expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. The upper low setting into southern
California the previous period is expected to move little this day,
remaining centered near the California/Mexico border. This will
help to maintain anomalous moisture across the region, fueling
widespread shower and thunderstorm coverage during the afternoon
and evening hours. A Slight Risk, with a footprint similar to the
Day 2 area, was maintained for Day 3 across parts of Arizona and
New Mexico.

...Southeast...

A boundary will remain in place across the Southeast as an upper
trough evolves into a closed low that is forecast to linger beyond
the period. Moisture and energy lifting ahead of the closing system
will support periods of shower and storms. While the guidance at
this point is not signaling any widespread heavy amounts, the
pattern does lend itself to at least the threat for locally heavy
amounts, which may raise at least isolated flooding concerns.

Pereira

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7h4VVW7j7L5JsErW2RNQmscZ04LZff35tUvNiuqwwR1X= Ab5Lcbz3WllKKKh2XWXbxH3PmOkY19s6T_hRas36BwJgqKg$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7h4VVW7j7L5JsErW2RNQmscZ04LZff35tUvNiuqwwR1X= Ab5Lcbz3WllKKKh2XWXbxH3PmOkY19s6T_hRas36N8rbaAc$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7h4VVW7j7L5JsErW2RNQmscZ04LZff35tUvNiuqwwR1X= Ab5Lcbz3WllKKKh2XWXbxH3PmOkY19s6T_hRas36NAnUHvc$=20

=3D =3D =3D
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FOUS30 KWBC 250046
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
846 PM EDT Wed Sep 24 2025

Day 1
Valid 01Z Thu Sep 25 2025 - 12Z Thu Sep 25 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE OHIO=20
VALLEY AND PORTIONS OF SOUTH TEXAS...

...01Z Update...

...Ohio and Tennessee Valleys...

Rain associated with a pair of disturbances is developing across
the lower Ohio Valley this evening. The locally heavy rain
associated with embedded convection will spread northeast up the
Ohio Valley, where rain from recent days has moistened the soils
somewhat. Thus, the Slight Risk was adjusted north, but remains in
place for the potential for widely scattered instances of flash
flooding. Further south into the Tennessee Valley the rain is
generally more progressive, less widespread, and there are large
areas with no rain occurring. Those areas have been dropped down to
a Marginal with this update.

...South Texas...

Developing convection along a cold frontal interface is expected to
become more widespread overnight, though model agreement on how
that convection behaves once formed is poor. The frontal interface
will likely be where the most persistent convection forms and
remains before likely pushing south into the heat and instability
in place across Deep South Texas. Thus, the rather narrow corridor
from Corpus Christi on the coast to Laredo on the Rio Grande is=20
likely where the highest chances for flash flooding will be through
tonight.

Wegman


Day 2
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

...Southwest to Sierra Nevada...

After moving inland early Thursday, the closed low over central
California is forecast to drop south into southern California by
early Friday. With ample moisture remaining in place (2-3 std
dev above normal) near and east of the upper center, locally heavy
amounts are possible from the Sierra Nevada east into southern
Nevada and southwestern Utah.

As the center drops south, increasing southerly flow east of the
low will draw deeper moisture up from Mexico, fueling widespread
shower and thunderstorm coverage, especially across southeastern
and central Arizona into southwestern New Mexico. A Slight Risk
was maintained across this area where PWs are forecast to increase
to 1-2 standard deviations above normal by the afternoon.

...Northeast...

Unsettled weather developing Day 1 is forecast to continue into
Thursday as showers and storms continue to develop ahead of the
system lifting out of the Ohio Valley into the Northeast.
Strengthening southwesterly flow along the Mid Atlantic coast into
the Northeast will support deepening moisture (PWs increasing to ~2
inches) and an increasing threat for heavy rainfall rates. A
Marginal Risk was maintained from northern New Jersey into southern
New England, where HREF probabilities indicate that localized
amounts over 3 inches are possible late Thursday morning into the
afternoon.

...Southern Appalachians into parts of the Southeast and Eastern
Gulf Coast...

...2000 UTC Update...

Amplifying mid-upper trough digging into the northwest and north-
central Gulf Thu-Thu night will slow the eastward progression of
the surface cold front and thus favorable pre-frontal buoyant
airmass (ribbon of higher TPW and deep-layer instability). More
protracted period of favorable low-level moisture transport ahead
of the upper trough/surface front. 12Z HREF probabilities depict
this idea well, with several hours of spotty areas with enhanced
probs for 1-2+ in/hr rainfall rates. Therefore, supported by the
latest CSU UFVS-verified ERO First-Guess field, have expanded the
Marginal Risk south to the MS-AL-western FL Panhandle Gulf Coast.


...Previous Discussion...

The consensus of the latest guidance indicates that showers and
storms developing along and ahead of the cold front trailing the
low moving through the Northeast will be generally progressive.
With widespread heavy amounts not expected and FFGs high, the
previous Marginal Risk was removed from much of the Mid Atlantic.
However, some models do show the potential for training storms to
produce some localized heavy amounts (2+ inches) across parts of
the southern Appalachians, where a small Marginal Risk was
maintained.

Hurley/Pereira


Day 3
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...

A second day of numerous showers and storms is expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. The upper low setting into southern
California the previous period is expected to move little this day,
remaining centered near the California/Mexico border. This will
help to maintain anomalous moisture across the region, fueling
widespread shower and thunderstorm coverage during the afternoon
and evening hours. A Slight Risk, with a footprint similar to the
Day 2 area, was maintained for Day 3 across parts of Arizona and
New Mexico.

...Southeast...

A boundary will remain in place across the Southeast as an upper
trough evolves into a closed low that is forecast to linger beyond
the period. Moisture and energy lifting ahead of the closing system
will support periods of shower and storms. While the guidance at
this point is not signaling any widespread heavy amounts, the
pattern does lend itself to at least the threat for locally heavy
amounts, which may raise at least isolated flooding concerns.

Pereira

Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!4QDYoBFeNMOd1Ld9bCQPgYzlRQX5emLDwLwCBoyFY48R= Clcn8tnCyqBzBMMpEAOMrOQUBya-8ZfpL6lqWvLjXgO07DA$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!4QDYoBFeNMOd1Ld9bCQPgYzlRQX5emLDwLwCBoyFY48R= Clcn8tnCyqBzBMMpEAOMrOQUBya-8ZfpL6lqWvLjv9146VM$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!4QDYoBFeNMOd1Ld9bCQPgYzlRQX5emLDwLwCBoyFY48R= Clcn8tnCyqBzBMMpEAOMrOQUBya-8ZfpL6lqWvLjPA8nWGM$=20

=3D =3D =3D
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FOUS30 KWBC 250744
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
344 AM EDT Thu Sep 25 2025

Day 1
Valid 12Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO...

...Southwest to Sierra Nevada...
A cold low near the central California coast is forecast to drop=20
southeast into southern California by early Friday. With cold air=20
aloft overlying sufficient moisture near and east of the upper=20
center, locally heavy amounts are possible from the Sierra Nevada=20
east into southern Nevada and southwestern Utah.

Ahead of the system, increasing southerly flow will draw deeper=20
moisture into the Southwest from the Gulf of CA, fueling=20
widespread shower and thunderstorm coverage, especially across=20
southeastern and central Arizona into southwestern New Mexico. ML=20
CAPE should rise into the 1000-2000 J/kg range. A Slight Risk was=20
maintained across this area where cold air aloft interacts with=20
monsoon-like moisture, with precipitable water values as high as=20
1.25-1.5". Hourly rain amounts to 2" are possible where cells merge
and/or train.


...Northeast/Upper Ohio Valley...
Unsettled weather at the present time is forecast to continue into
Thursday as showers and storms stream east across the Upper Ohio
Valley, WV, and southwest PA ahead of a shortwave aloft and surface
frontal wave. While there may be a gap in heavy rainfall between=20
this region and points farther east, chose to connect the areas=20
and significantly broaden the inherited Marginal Risk.=20
Strengthening southwesterly flow along the Mid Atlantic coast into=20
the Northeast will support deepening moisture (PWs increasing to=20
~2") and ML CAPE surpasses 1000 J/kg. Hourly amounts to 2.5" are=20
possible in this region with local totals to 4", but coverage of
such amounts should be sparse enough for a Marginal Risk to still
apply.


...Southern Appalachians into parts of the Gulf Coast...
Amplifying mid-upper trough digging into the northwest and north-=20
central Gulf will slow the south and east progression of the=20
surface cold front and pre-frontal buoyant airmass. ML CAPE values
should rise to 1000 J/kg or so across the southernmost=20
Appalachians while areas of the Gulf Coast see 2000-3000 J/kg of ML
CAPE. With precipitable water values at or above 2", hourly rain=20
amounts to 2.5" with local totals to 4" are possible wherever short
periods of training or cell mergers are able to occur. Activity=20
currently across South TX should survive past 12z, so looped the=20
Marginal Risk to encompass this area. At the present time, any
flash flood issues are expected to be isolated to widely scattered.

Roth


Day 2
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...
Numerous showers and thunderstorms are expected across the=20
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. An upper low should slow to a crawl=20
across southeast California. Precipitable water values should=20
remain as high as 1.25-1.5" in spots, but the guidance shows more=20
potential on the ML CAPE front when compared to Thursday, with=20
values of 2000-3000 J/kg possible as available moisture interacts=20
with the cold pool aloft. Widespread shower and thunderstorm=20
coverage is expected, particularly during the afternoon and evening
hours. A Slight Risk, with a footprint similar to the Day 2 area,=20
was maintained for Day 3 across parts of Arizona and New Mexico,=20
but it could be higher end Slight Risk. Hourly rain amounts to 2"=20
are possible where cells merge and/or train.

...Southeast...
A boundary will remain in place as a cold low forms near the base
of an upper level trough, a feature that lingers for a while near
the Southern Appalachians. Moisture and instability lifting ahead=20
of the closing system will support periods of showers and storms.=20 Precipitable water values of up to 2" with ML CAPE to 1000 J/kg=20
across the Piedmont and 2000-3000 J/kg in coastal areas are=20
expected, which could yield hourly rain amounts to 2.5" and local=20
totals to 4".

Roth


Day 3
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS & NEW MEXICO...

Southwest/Southern Rockies...
An upper low remains fixed across the Lower Colorado River while=20
Gulf Moisture streams into the TX Big Bend and New Mexico, moving=20
up the Rio Grande. Precipitable water values of 1.25-1.5" are=20
forecast, which when combined with up to 1000 J/kg of ML CAPE could
yield hourly amounts to 2.5" and local totals to 4" where cells=20
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far=20
west TX and NM. Closer to the upper level center across the=20
Southwest, slow-moving convection is possible under the cold pool=20
aloft. Based on the decline of the 1000-500 hPa thickness across UT
towards 5670 meters, limited the northern extent of the Marginal=20
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value, which was coordinated with the SLC/Salt=20
Lake City forecast office.


Carolinas/Southern Mid-Atlantic States...
Divergence aloft around the eastern periphery of a cold low near=20
the Southern Appalachians maintains precipitable water values of=20
2"+ near the coast, which should also see the greatest instability,
up to 1000 J/kg. The guidance shows a bit of dispersion here in=20 placement/northeast movement of the heavy rain area with the GFS=20
and NAM in their usual camps (fast and slow, respectively). Hourly
rain amounts to 2.5" and local totals to 4" are expected, similar=20
to previous days. Forecast uncertainty, as much as anything else,
maintained the risk level as a Marginal. Should the guidance
converge, areas of risk overlap between Friday and Saturday across
portions of the coastal plain of the Carolinas could see an upgrade
to a Slight Risk at some point as we get closer to Saturday.

Roth


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8d6S6hXccTsH19rRH0Qi33rV8GxukYYaBJ1hptk_YTN2= AWJBYiyy2bTfeMod-9cDlmloi4Pv0WJhyUPQNkA4bHetHY4$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8d6S6hXccTsH19rRH0Qi33rV8GxukYYaBJ1hptk_YTN2= AWJBYiyy2bTfeMod-9cDlmloi4Pv0WJhyUPQNkA4iTG57mM$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8d6S6hXccTsH19rRH0Qi33rV8GxukYYaBJ1hptk_YTN2= AWJBYiyy2bTfeMod-9cDlmloi4Pv0WJhyUPQNkA4OZkyHfw$=20

=3D =3D =3D
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FOUS30 KWBC 251558
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1158 AM EDT Thu Sep 25 2025

Day 1
Valid 16Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO, ALONG WITH PARTS OF EASTERN
CALIFORNIA INTO WESTERN NEVADA...

...Southwest to Sierra Nevada...

...1600 UTC Update...

Per collaboration with affected WFOs, have hoisted a Slight Risk
area across the central Sierra (south of Lake Tahoe) into parts of
western NV. This was based on some of the guidance trends,
including the 06Z HREF and RRFS ensembles, and continuing with the
12Z CAMs. The 12Z HREF Z HREF probs of 0.50+ in/hr rates are aoa=20
70% between 19-03Z this evening, while probs of 3-hourly QPF=20
exceeding 3-hourly FFG top out between 40-50%, which is impressive.

...Previous discussion...

A cold low near the central California coast is forecast to drop
southeast into southern California by early Friday. With cold air
aloft overlying sufficient moisture near and east of the upper
center, locally heavy amounts are possible from the Sierra Nevada
east into southern Nevada and southwestern Utah.

Ahead of the system, increasing southerly flow will draw deeper
moisture into the Southwest from the Gulf of CA, fueling
widespread shower and thunderstorm coverage, especially across
southeastern and central Arizona into southwestern New Mexico. ML
CAPE should rise into the 1000-2000 J/kg range. A Slight Risk was
maintained across this area where cold air aloft interacts with
monsoon-like moisture, with precipitable water values as high as
1.25-1.5". Hourly rain amounts to 2" are possible where cells merge
and/or train.


...Northeast/Upper Ohio Valley...
Unsettled weather at the present time is forecast to continue into
Thursday as showers and storms stream east across the Upper Ohio
Valley, WV, and southwest PA ahead of a shortwave aloft and surface
frontal wave. While there may be a gap in heavy rainfall between
this region and points farther east, chose to connect the areas
and significantly broaden the inherited Marginal Risk.
Strengthening southwesterly flow along the Mid Atlantic coast into
the Northeast will support deepening moisture (PWs increasing to
~2") and ML CAPE surpasses 1000 J/kg. Hourly amounts to 2.5" are
possible in this region with local totals to 4", but coverage of
such amounts should be sparse enough for a Marginal Risk to still
apply.


...Southern Appalachians into parts of the Gulf Coast...
Amplifying mid-upper trough digging into the northwest and north-
central Gulf will slow the south and east progression of the
surface cold front and pre-frontal buoyant airmass. ML CAPE values
should rise to 1000 J/kg or so across the southernmost
Appalachians while areas of the Gulf Coast see 2000-3000 J/kg of ML
CAPE. With precipitable water values at or above 2", hourly rain
amounts to 2.5" with local totals to 4" are possible wherever short
periods of training or cell mergers are able to occur. Activity
currently across South TX should survive past 12z, so looped the
Marginal Risk to encompass this area. At the present time, any
flash flood issues are expected to be isolated to widely scattered.

Roth


Day 2
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...
Numerous showers and thunderstorms are expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. An upper low should slow to a crawl
across southeast California. Precipitable water values should
remain as high as 1.25-1.5" in spots, but the guidance shows more
potential on the ML CAPE front when compared to Thursday, with
values of 2000-3000 J/kg possible as available moisture interacts
with the cold pool aloft. Widespread shower and thunderstorm
coverage is expected, particularly during the afternoon and evening
hours. A Slight Risk, with a footprint similar to the Day 2 area,
was maintained for Day 3 across parts of Arizona and New Mexico,
but it could be higher end Slight Risk. Hourly rain amounts to 2"
are possible where cells merge and/or train.

...Southeast...
A boundary will remain in place as a cold low forms near the base
of an upper level trough, a feature that lingers for a while near
the Southern Appalachians. Moisture and instability lifting ahead
of the closing system will support periods of showers and storms.
Precipitable water values of up to 2" with ML CAPE to 1000 J/kg
across the Piedmont and 2000-3000 J/kg in coastal areas are
expected, which could yield hourly rain amounts to 2.5" and local
totals to 4".

Roth


Day 3
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS & NEW MEXICO...

Southwest/Southern Rockies...
An upper low remains fixed across the Lower Colorado River while
Gulf Moisture streams into the TX Big Bend and New Mexico, moving
up the Rio Grande. Precipitable water values of 1.25-1.5" are
forecast, which when combined with up to 1000 J/kg of ML CAPE could
yield hourly amounts to 2.5" and local totals to 4" where cells
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far
west TX and NM. Closer to the upper level center across the
Southwest, slow-moving convection is possible under the cold pool
aloft. Based on the decline of the 1000-500 hPa thickness across UT
towards 5670 meters, limited the northern extent of the Marginal
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value, which was coordinated with the SLC/Salt
Lake City forecast office.


Carolinas/Southern Mid-Atlantic States...
Divergence aloft around the eastern periphery of a cold low near
the Southern Appalachians maintains precipitable water values of
2"+ near the coast, which should also see the greatest instability,
up to 1000 J/kg. The guidance shows a bit of dispersion here in placement/northeast movement of the heavy rain area with the GFS
and NAM in their usual camps (fast and slow, respectively). Hourly
rain amounts to 2.5" and local totals to 4" are expected, similar
to previous days. Forecast uncertainty, as much as anything else,
maintained the risk level as a Marginal. Should the guidance
converge, areas of risk overlap between Friday and Saturday across
portions of the coastal plain of the Carolinas could see an upgrade
to a Slight Risk at some point as we get closer to Saturday.

Roth


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5Tqu12PgsKTP4SrXRi0HHmNGrgquFsh7PveHA1GRB2ab= e6avY1VTV7Mpxt0LZe9v8I-z_t5o3mbeDtjolqO7Sq3Zl00$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5Tqu12PgsKTP4SrXRi0HHmNGrgquFsh7PveHA1GRB2ab= e6avY1VTV7Mpxt0LZe9v8I-z_t5o3mbeDtjolqO7Uxmygm0$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5Tqu12PgsKTP4SrXRi0HHmNGrgquFsh7PveHA1GRB2ab= e6avY1VTV7Mpxt0LZe9v8I-z_t5o3mbeDtjolqO7CxXHzDw$=20

=3D =3D =3D
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FOUS30 KWBC 251559
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1159 AM EDT Thu Sep 25 2025

Day 1
Valid 16Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO, ALONG WITH PARTS OF EASTERN
CALIFORNIA INTO WESTERN NEVADA...

...Southwest to Sierra Nevada...

...1600 UTC Update...

Per collaboration with affected WFOs, have hoisted a Slight Risk
area across the central Sierra (south of Lake Tahoe) into parts of
western NV. This was based on some of the guidance trends,
including the 06Z HREF and RRFS ensembles, and continuing with the
12Z CAMs. The 12Z HREF Z HREF probs of 0.50+ in/hr rates are aoa
70% between 19-03Z this evening, while probs of 3-hourly QPF
exceeding 3-hourly FFG top out between 40-50%, which is impressive.

...Previous discussion...

A cold low near the central California coast is forecast to drop
southeast into southern California by early Friday. With cold air
aloft overlying sufficient moisture near and east of the upper
center, locally heavy amounts are possible from the Sierra Nevada
east into southern Nevada and southwestern Utah.

Ahead of the system, increasing southerly flow will draw deeper
moisture into the Southwest from the Gulf of CA, fueling
widespread shower and thunderstorm coverage, especially across
southeastern and central Arizona into southwestern New Mexico. ML
CAPE should rise into the 1000-2000 J/kg range. A Slight Risk was
maintained across this area where cold air aloft interacts with
monsoon-like moisture, with precipitable water values as high as
1.25-1.5". Hourly rain amounts to 2" are possible where cells merge
and/or train.


...Northeast/Upper Ohio Valley...
Unsettled weather at the present time is forecast to continue into
Thursday as showers and storms stream east across the Upper Ohio
Valley, WV, and southwest PA ahead of a shortwave aloft and surface
frontal wave. While there may be a gap in heavy rainfall between
this region and points farther east, chose to connect the areas
and significantly broaden the inherited Marginal Risk.
Strengthening southwesterly flow along the Mid Atlantic coast into
the Northeast will support deepening moisture (PWs increasing to
~2") and ML CAPE surpasses 1000 J/kg. Hourly amounts to 2.5" are
possible in this region with local totals to 4", but coverage of
such amounts should be sparse enough for a Marginal Risk to still
apply.


...Southern Appalachians into parts of the Gulf Coast...
Amplifying mid-upper trough digging into the northwest and north-
central Gulf will slow the south and east progression of the
surface cold front and pre-frontal buoyant airmass. ML CAPE values
should rise to 1000 J/kg or so across the southernmost
Appalachians while areas of the Gulf Coast see 2000-3000 J/kg of ML
CAPE. With precipitable water values at or above 2", hourly rain
amounts to 2.5" with local totals to 4" are possible wherever short
periods of training or cell mergers are able to occur. At the=20
present time, any flash flood issues are expected to be isolated to
widely scattered.

Roth


Day 2
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...
Numerous showers and thunderstorms are expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. An upper low should slow to a crawl
across southeast California. Precipitable water values should
remain as high as 1.25-1.5" in spots, but the guidance shows more
potential on the ML CAPE front when compared to Thursday, with
values of 2000-3000 J/kg possible as available moisture interacts
with the cold pool aloft. Widespread shower and thunderstorm
coverage is expected, particularly during the afternoon and evening
hours. A Slight Risk, with a footprint similar to the Day 2 area,
was maintained for Day 3 across parts of Arizona and New Mexico,
but it could be higher end Slight Risk. Hourly rain amounts to 2"
are possible where cells merge and/or train.

...Southeast...
A boundary will remain in place as a cold low forms near the base
of an upper level trough, a feature that lingers for a while near
the Southern Appalachians. Moisture and instability lifting ahead
of the closing system will support periods of showers and storms.
Precipitable water values of up to 2" with ML CAPE to 1000 J/kg
across the Piedmont and 2000-3000 J/kg in coastal areas are
expected, which could yield hourly rain amounts to 2.5" and local
totals to 4".

Roth


Day 3
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS & NEW MEXICO...

Southwest/Southern Rockies...
An upper low remains fixed across the Lower Colorado River while
Gulf Moisture streams into the TX Big Bend and New Mexico, moving
up the Rio Grande. Precipitable water values of 1.25-1.5" are
forecast, which when combined with up to 1000 J/kg of ML CAPE could
yield hourly amounts to 2.5" and local totals to 4" where cells
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far
west TX and NM. Closer to the upper level center across the
Southwest, slow-moving convection is possible under the cold pool
aloft. Based on the decline of the 1000-500 hPa thickness across UT
towards 5670 meters, limited the northern extent of the Marginal
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value, which was coordinated with the SLC/Salt
Lake City forecast office.


Carolinas/Southern Mid-Atlantic States...
Divergence aloft around the eastern periphery of a cold low near
the Southern Appalachians maintains precipitable water values of
2"+ near the coast, which should also see the greatest instability,
up to 1000 J/kg. The guidance shows a bit of dispersion here in placement/northeast movement of the heavy rain area with the GFS
and NAM in their usual camps (fast and slow, respectively). Hourly
rain amounts to 2.5" and local totals to 4" are expected, similar
to previous days. Forecast uncertainty, as much as anything else,
maintained the risk level as a Marginal. Should the guidance
converge, areas of risk overlap between Friday and Saturday across
portions of the coastal plain of the Carolinas could see an upgrade
to a Slight Risk at some point as we get closer to Saturday.

Roth


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5rFIq1evtVlwy1YC8dPM6VZyWSFgQI-8Dro3_N3WA49_= snStVkXqJPbLL755PAet-tPqsJqaq4oTD5PU6_EEE5LXC0o$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5rFIq1evtVlwy1YC8dPM6VZyWSFgQI-8Dro3_N3WA49_= snStVkXqJPbLL755PAet-tPqsJqaq4oTD5PU6_EEQ4VMtUQ$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5rFIq1evtVlwy1YC8dPM6VZyWSFgQI-8Dro3_N3WA49_= snStVkXqJPbLL755PAet-tPqsJqaq4oTD5PU6_EEXceNI-k$=20

=3D =3D =3D
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FOUS30 KWBC 251947
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
347 PM EDT Thu Sep 25 2025

Day 1
Valid 16Z Thu Sep 25 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO, ALONG WITH PARTS OF EASTERN
CALIFORNIA INTO WESTERN NEVADA...

...Southwest to Sierra Nevada...

...1600 UTC Update...
Per collaboration with affected WFOs, have hoisted a Slight Risk=20
area across the central Sierra (south of Lake Tahoe) into parts of=20
western NV. This was based on some of the guidance trends,=20
including the 06Z HREF and RRFS ensembles, and continuing with the=20
12Z CAMs. The 12Z HREF Z HREF probs of 0.50+ in/hr rates are aoa=20
70% between 19-03Z this evening, while probs of 3-hourly QPF=20
exceeding 3-hourly FFG top out between 40-50%, which is impressive.

...Previous discussion...
A cold low near the central California coast is forecast to drop=20
southeast into southern California by early Friday. With cold air=20
aloft overlying sufficient moisture near and east of the upper=20
center, locally heavy amounts are possible from the Sierra Nevada=20
east into southern Nevada and southwestern Utah.

Ahead of the system, increasing southerly flow will draw deeper
moisture into the Southwest from the Gulf of CA, fueling
widespread shower and thunderstorm coverage, especially across
southeastern and central Arizona into southwestern New Mexico. ML
CAPE should rise into the 1000-2000 J/kg range. A Slight Risk was
maintained across this area where cold air aloft interacts with
monsoon-like moisture, with precipitable water values as high as
1.25-1.5". Hourly rain amounts to 2" are possible where cells merge
and/or train.

...Northeast/Upper Ohio Valley...
Unsettled weather at the present time is forecast to continue into
Thursday as showers and storms stream east across the Upper Ohio=20
Valley, WV, and southwest PA ahead of a shortwave aloft and surface
frontal wave. While there may be a gap in heavy rainfall between=20
this region and points farther east, chose to connect the areas and significantly broaden the inherited Marginal Risk. Strengthening=20 southwesterly flow along the Mid Atlantic coast into the Northeast=20
will support deepening moisture (PWs increasing to ~2") and ML CAPE
surpasses 1000 J/kg. Hourly amounts to 2.5" are possible in this=20
region with local totals to 4", but coverage of such amounts should
be sparse enough for a Marginal Risk to still apply.

...Southern Appalachians into parts of the Gulf Coast...
Amplifying mid-upper trough digging into the northwest and north-=20
central Gulf will slow the south and east progression of the=20
surface cold front and pre-frontal buoyant airmass. ML CAPE values=20
should rise to 1000 J/kg or so across the southernmost Appalachians
while areas of the Gulf Coast see 2000-3000 J/kg of ML CAPE. With=20 precipitable water values at or above 2", hourly rain amounts to=20
2.5" with local totals to 4" are possible wherever short periods of
training or cell mergers are able to occur. At the present time,=20
any flash flood issues are expected to be isolated to widely=20
scattered.

Hurley/Roth


Day 2
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...

...2000 UTC Update...
At most, only minor changes made to the Day 2 ERO. Most notably,=20
we expanded the Slight Risk area slightly westward, which now=20
includes the Phoenix metro region and is closer to to Prescott and=20 Flagstaff. This is based on the latest (more elevated_ HREF and=20
RRFS rainfall exceedance probabilities for Friday afternoon and=20
evening, especially the probs for 0.50-1.00+ in/hr rainfall, along=20
with the probs of 3-hourly rainfall exceeding current 3-hour FFG=20

40% within the Slight Risk area between 20-03Z).

...Previous Discussion...
Numerous showers and thunderstorms are expected across the=20
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. An upper low should slow to a crawl=20
across southeast California. Precipitable water values should=20
remain as high as 1.25-1.5" in spots, but the guidance shows more=20
potential on the ML CAPE front when compared to Thursday, with=20
values of 2000-3000 J/kg possible as available moisture interacts=20
with the cold pool aloft. Widespread shower and thunderstorm=20
coverage is expected, particularly during the afternoon and evening
hours. A Slight Risk, with a footprint similar to the Day 2 area,=20
was maintained for Day 3 across parts of Arizona and New Mexico,=20
but it could be higher end Slight Risk. Hourly rain amounts to 2"=20
are possible where cells merge and/or train.

...Southeast...
A boundary will remain in place as a cold low forms near the base=20
of an upper level trough, a feature that lingers for a while near=20
the Southern Appalachians. Moisture and instability lifting ahead=20
of the closing system will support periods of showers and storms.=20 Precipitable water values of up to 2" with ML CAPE to 1000 J/kg=20
across the Piedmont and 2000-3000 J/kg in coastal areas are=20
expected, which could yield hourly rain amounts to 2.5" and local=20
totals to 4".

Roth


Day 3
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS & NEW MEXICO...

...Southwest/Southern Rockies...

...2000 UTC Update...
Expanded the Slight Risk area across NM, particularly northwest=20
NM, based on the latest (12Z) deterministic and probabilistic=20
guidance trends with the deepening low eventually cutting over=20
southeast CA/southwest AZ by Saturday. Model QPFs seem to be=20
convergence, which is boosting confidence to expand the Slight=20
farther north toward the NM-CO border. The area also aligns with=20
where the ECMWF and GFS show highest MUCAPEs (at least 500 J/Kg).=20

...Previous Discussion...
An upper low remains fixed across the Lower Colorado River while=20
Gulf Moisture streams into the TX Big Bend and New Mexico, moving=20
up the Rio Grande. Precipitable water values of 1.25-1.5" are=20
forecast, which when combined with up to 1000 J/kg of ML CAPE could
yield hourly amounts to 2.5" and local totals to 4" where cells=20
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far=20
west TX and NM. Closer to the upper level center across the=20
Southwest, slow-moving convection is possible under the cold pool=20
aloft. Based on the decline of the 1000-500 hPa thickness across UT
towards 5670 meters, limited the northern extent of the Marginal=20
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value, which was coordinated with the SLC/Salt=20
Lake City forecast office.

...Carolinas/Southern Mid-Atlantic States...

...2000 UTC Update...
Minimal changes made to the previous Day 3 ERO in this area. Still
cannot rule an upgrade to a Slight Risk somewhere over the Coastal
Plain from SC-VA (see previous discussion); however, the guidance=20
spread with respect to the QPF remains quite a bit high at this=20
time to include a targeted Slight Risk area.

...Previous Discussion...
Divergence aloft around the eastern periphery of a cold low near=20
the Southern Appalachians maintains precipitable water values of=20
2"+ near the coast, which should also see the greatest instability,
up to 1000 J/kg. The guidance shows a bit of dispersion here in=20 placement/northeast movement of the heavy rain area with the GFS=20
and NAM in their usual camps (fast and slow, respectively). Hourly=20
rain amounts to 2.5" and local totals to 4" are expected, similar=20
to previous days. Forecast uncertainty, as much as anything else,=20
maintained the risk level as a Marginal. Should the guidance=20
converge, areas of risk overlap between Friday and Saturday across=20
portions of the coastal plain of the Carolinas could see an upgrade
to a Slight Risk at some point as we get closer to Saturday.

Hurley/Roth


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-h3bSQrJyfY3Z5jDR128vyuG0vaHTpcJTNKqqKe1_Lo_= UUO6AwusAYuGLUenFtvOVVvse12ErqsVBQJ1leSktUVghXA$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-h3bSQrJyfY3Z5jDR128vyuG0vaHTpcJTNKqqKe1_Lo_= UUO6AwusAYuGLUenFtvOVVvse12ErqsVBQJ1leSk1-OEGKs$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-h3bSQrJyfY3Z5jDR128vyuG0vaHTpcJTNKqqKe1_Lo_= UUO6AwusAYuGLUenFtvOVVvse12ErqsVBQJ1leSkF5k59XU$=20

=3D =3D =3D
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FOUS30 KWBC 260038
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
838 PM EDT Thu Sep 25 2025

Day 1
Valid 01Z Fri Sep 26 2025 - 12Z Fri Sep 26 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND FAR SOUTHWEST NEW MEXICO, ALONG WITH PARTS OF EASTERN
CALIFORNIA INTO WESTERN NEVADA...

...01Z Update...

...Southwest...

Moisture streaming north around a digging positively tilted trough
has resulting in a corridor of showers and thunderstorms extending
from the AZ/NM/Mexico tripoint north and west to west-central
Nevada. The strongest storms and by far the most prolific flash
flooding are across eastern Arizona into southwestern New Mexico,
where atmospheric moisture levels are their highest. Heavy rain
associated with scattered thunderstorms will likely continue for a
few more hours with daytime heating, then will rapidly diminish in
coverage and intensity after sunset. A similar scenario is also
occurring up north, where a Slight Risk area covers a portion of
the NV/CA border south of Lake Tahoe. In similar fashion as=20
further south, the steady rain will likely persist for another few=20
hours, followed by rapid weakening and dissipation of all=20
precipitation producing showers and storms soon after sunset. The=20
Slight Risk in this area was expanded north to cover some of the=20
flash flooding occurring southeast of Lake Tahoe, but overall a=20
very minor adjustment.

...Northeast...

The inherited Marginal Risk across the Northeast was split with
this update to the area around the OH/WV/PA tripoint and the
northern West Virginia Panhandle, with a second one for much of
southern New England. In the upper Ohio Valley, scattered showers
and storms over southeastern Ohio are moving into an area hard hit
with heavy rain in recent days. Thus, even small amounts of rain in
this terrain may result in renewed flash flooding. Into New
England, a line of moderate to heavy rain is moving into western
New England, and may cause isolated flash flooding in areas that
have seen more rain from the area of rain now moving across Maine,
otherwise the flash flooding threat has largely ended, especially
in most of PA and NY.

...Southeast...

No major changes were made as ongoing clusters of showers and
thunderstorms may still pose an isolated flash flooding threat into
the overnight, though overall coverage should continue gradually
decreasing with the loss of solar heating.

Wegman


Day 2
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS SOUTHEAST
ARIZONA AND SOUTHWEST NEW MEXICO...

...Southwest...

...2000 UTC Update...
At most, only minor changes made to the Day 2 ERO. Most notably,
we expanded the Slight Risk area slightly westward, which now
includes the Phoenix metro region and is closer to to Prescott and
Flagstaff. This is based on the latest (more elevated_ HREF and
RRFS rainfall exceedance probabilities for Friday afternoon and
evening, especially the probs for 0.50-1.00+ in/hr rainfall, along
with the probs of 3-hourly rainfall exceeding current 3-hour FFG

40% within the Slight Risk area between 20-03Z).

...Previous Discussion...
Numerous showers and thunderstorms are expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico. An upper low should slow to a crawl
across southeast California. Precipitable water values should
remain as high as 1.25-1.5" in spots, but the guidance shows more
potential on the ML CAPE front when compared to Thursday, with
values of 2000-3000 J/kg possible as available moisture interacts
with the cold pool aloft. Widespread shower and thunderstorm
coverage is expected, particularly during the afternoon and evening
hours. A Slight Risk, with a footprint similar to the Day 2 area,
was maintained for Day 3 across parts of Arizona and New Mexico,
but it could be higher end Slight Risk. Hourly rain amounts to 2"
are possible where cells merge and/or train.

...Southeast...
A boundary will remain in place as a cold low forms near the base
of an upper level trough, a feature that lingers for a while near
the Southern Appalachians. Moisture and instability lifting ahead
of the closing system will support periods of showers and storms.
Precipitable water values of up to 2" with ML CAPE to 1000 J/kg
across the Piedmont and 2000-3000 J/kg in coastal areas are
expected, which could yield hourly rain amounts to 2.5" and local
totals to 4".

Roth


Day 3
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS & NEW MEXICO...

...Southwest/Southern Rockies...

...2000 UTC Update...
Expanded the Slight Risk area across NM, particularly northwest
NM, based on the latest (12Z) deterministic and probabilistic
guidance trends with the deepening low eventually cutting over
southeast CA/southwest AZ by Saturday. Model QPFs seem to be
convergence, which is boosting confidence to expand the Slight
farther north toward the NM-CO border. The area also aligns with
where the ECMWF and GFS show highest MUCAPEs (at least 500 J/Kg).

...Previous Discussion...
An upper low remains fixed across the Lower Colorado River while
Gulf Moisture streams into the TX Big Bend and New Mexico, moving
up the Rio Grande. Precipitable water values of 1.25-1.5" are
forecast, which when combined with up to 1000 J/kg of ML CAPE could
yield hourly amounts to 2.5" and local totals to 4" where cells
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far
west TX and NM. Closer to the upper level center across the
Southwest, slow-moving convection is possible under the cold pool
aloft. Based on the decline of the 1000-500 hPa thickness across UT
towards 5670 meters, limited the northern extent of the Marginal
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value, which was coordinated with the SLC/Salt
Lake City forecast office.

...Carolinas/Southern Mid-Atlantic States...

...2000 UTC Update...
Minimal changes made to the previous Day 3 ERO in this area. Still
cannot rule an upgrade to a Slight Risk somewhere over the Coastal
Plain from SC-VA (see previous discussion); however, the guidance
spread with respect to the QPF remains quite a bit high at this
time to include a targeted Slight Risk area.

...Previous Discussion...
Divergence aloft around the eastern periphery of a cold low near
the Southern Appalachians maintains precipitable water values of
2"+ near the coast, which should also see the greatest instability,
up to 1000 J/kg. The guidance shows a bit of dispersion here in placement/northeast movement of the heavy rain area with the GFS
and NAM in their usual camps (fast and slow, respectively). Hourly
rain amounts to 2.5" and local totals to 4" are expected, similar
to previous days. Forecast uncertainty, as much as anything else,
maintained the risk level as a Marginal. Should the guidance
converge, areas of risk overlap between Friday and Saturday across
portions of the coastal plain of the Carolinas could see an upgrade
to a Slight Risk at some point as we get closer to Saturday.

Hurley/Roth


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6YmSsLc3Hz2al0zQa0LUEiA65zKbo3NmcArBMC2w4u0j= 6sIEdJQsLJb9ozBTBFysqxBt2hYZ-jgkY4SDI6ZyvOoooXk$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6YmSsLc3Hz2al0zQa0LUEiA65zKbo3NmcArBMC2w4u0j= 6sIEdJQsLJb9ozBTBFysqxBt2hYZ-jgkY4SDI6ZyZmehpr0$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6YmSsLc3Hz2al0zQa0LUEiA65zKbo3NmcArBMC2w4u0j= 6sIEdJQsLJb9ozBTBFysqxBt2hYZ-jgkY4SDI6ZyOY64Im8$=20

=3D =3D =3D
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FOUS30 KWBC 260808
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
408 AM EDT Fri Sep 26 2025

Day 1
Valid 12Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST & IN THE VICINITY OF THE CAROLINAS...

...Southwest...
Numerous showers and thunderstorms are expected across the=20
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico, which should occur primarily during the
afternoon and evening hours. An upper low should slow to a crawl=20
across southeast California. Precipitable water values should=20
remain as high as 1.25-1.5" in spots. ML CAPE values of 2000-3000=20
J/kg are possible as available moisture interacts with the cold=20
pool aloft. A Slight Risk was maintained across parts of Arizona=20
and New Mexico, but it could be higher end Slight Risk. Hourly rain
amounts to 2" with local totals to 4" are possible where cells=20
merge and/or train.


...Southeast...
A boundary will remain in place as a cold low forms near the base
of an upper level trough, a feature that lingers for a while near
the Southern Appalachians. Farther inland across the Piedmont, some
degree of upslope flow should bring some of the higher moisture
back in from the southeast. Moisture and instability lifting ahead
of the closing system will support periods of showers and storms.=20 Precipitable water values of up to 2" with MU CAPE of 1000+ J/kg=20
across the Piedmont and 2000-3000 J/kg in coastal areas are=20
expected, which could yield hourly rain amounts to 2.5" and local=20
totals to 4". As the 00z HREF and 18z REFS had their strongest=20
signal for 3"+ and 5"+ across far southwest VA and the western=20
Carolinas, a Slight Risk was added in this update, which was=20
coordinated with the local offices. For the time being, a Slight=20
Risk was left out across the coastal plain of the Carolinas as=20
recent dryness could make a higher incidence of flash flooding=20
harder to come by, which was coordinated with the coastal Carolina=20
offices.

Roth


Day 2
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025


...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS & NEW MEXICO...

...Southwest/Southern Rockies...
An upper low remains fixed across the Lower Colorado River while=20
Gulf Moisture streams into the TX Big Bend and New Mexico, moving=20
up the Rio Grande. Precipitable water values of 1.25-1.5" are=20
forecast, which when combined with 1000+ J/kg of ML CAPE could=20
yield hourly amounts to 2.5" and local totals to 4" where cells=20
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far=20
west TX and NM. Closer to the upper level center across the=20
Southwest, slow-moving convection is possible under the cold pool=20
aloft, with ML CAPE of 1000-2000 J/kg of instability and
precipitable water values in the Lower Desert of 1-1.25" expected.
Based on the decline of the 1000-500 hPa thickness across UT=20
towards 5670 meters, limited the northern extent of the Marginal=20
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value.


...Carolinas/Southern Mid-Atlantic States...
Divergence aloft around the eastern periphery of a cold low near=20
the Southern Appalachians and what is now a tropical disturbance
moving through the Bahamas as a possible tropical cyclone on=20
Saturday team up to maintain precipitable water values of up to
2.25" across the coastal plain, which should also see the greatest
instability, 1000-2000 J/kg. The Piedmont should see times when the
MU CAPE rises above 500 J/kg. This is a PRE-like set up for the=20
region, so the heavy rainfall potential has a higher upside than=20
usual. There has been some convergence in the model guidance QPF-=20
wise, and both the 00z HREF and 18z REFS had a cohesive and=20
agreeable enough heavy rain threat of 3"+ for a new Slight Risk=20
area from roughly Richmond VA south on both sides of the fall line=20
into eastern SC. Hourly rain amounts to 3" and local totals to 6"=20
are possible, which is potentially problematic anywhere within the=20
Slight Risk area. A higher risk level can't be ruled out in future=20
updates.

Roth



Day 3
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS, NEW MEXICO, & THE CAROLINAS...

Southwest/Southern Rockies...
The combination of an upper low moving to near the Four Corners, a
kicker upper level trough moving into CA, and moisture feed from=20
the Gulf into NM persist into Sunday. Precipitable water values
remain above 1" locally in the Desert Southwest and 1-1.25" in the
Southern High Plains. Pockets of 1000+ J/kg of ML/MU CAPE are
forecast to develop and/or persist. A Slight Risk still appears=20
reasonable across portions of far west TX and NM, with a broader=20
Marginal Risk surrounding that. The guidance appears to be trending
somewhat drier across the Great Basin, so limited the northern=20
extent of the Marginal Risk area when compared to continuity.


Florida northward into the Southern Mid-Atlantic States...
A system now considered a tropical disturbance over Hispaniola
should lie somewhere north of the Bahamas and east of Florida as a
possible tropical or hybrid cyclone on Sunday. The upper level=20
environment doesn't look kind for whatever emerges, and there are=20
two scenarios -- a more convective system that remains offshore=20
during the medium range period or a more sheared system that=20
attempts to occlude when it approaches landfall early next week.=20
The guidance is not ideal in differentiating which is correct=20
during these scenarios, historically.=20

Regardless, moisture will not be a problem regionally --
precipitable water values locally 2"+. Coastal areas will see=20
1000+ J/kg of ML CAPE while 250+ J/kg of MU CAPE invades portions=20
of VA. The guidance has slowed down the approach of the tropical=20
low since yesterday, but the other players in the flow pattern=20
remain -- the upper low near the southern Appalachians/southern=20
Cumberland Plateau and the front near the East Coast. A PRE- like=20
set up appears to be in the cards, with moisture streaming into the
front from the south. The best signal for heavy rainfall on Sunday
into early Monday appears to be in the vicinity of Myrtle Beach,=20
and considering previous days of rain, thought a new Slight Risk in
that area would be prudent. In theory, hourly rain amounts to 3"=20
should be possible, which would be most problematic should=20
thunderstorms merge or train.

Roth


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7kCeOPjehPYiHHnnWyFIadM5ZEv3yQ4h7x500EE-ws-1= M87BBQ-OzLnFQYIBIvFPuY78zriws5PyHyHIhQw3T5d5Y3c$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7kCeOPjehPYiHHnnWyFIadM5ZEv3yQ4h7x500EE-ws-1= M87BBQ-OzLnFQYIBIvFPuY78zriws5PyHyHIhQw3Wqd56Fo$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7kCeOPjehPYiHHnnWyFIadM5ZEv3yQ4h7x500EE-ws-1= M87BBQ-OzLnFQYIBIvFPuY78zriws5PyHyHIhQw3FvcRo40$=20

=3D =3D =3D
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FOUS30 KWBC 261602
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1202 PM EDT Fri Sep 26 2025

Day 1
Valid 16Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST & IN THE VICINITY OF THE CAROLINAS...

16z Update: Not many changes needed to the inherited outlook from
earlier this morning. Central to southern AZ remains the focus for
potentially locally significant flash flooding. Pretty impressive
southerly inflow/moisture transport combined with upwards of 2000
J/KG of CAPE will support a backbuilding convective threat today.
Main question will be how much of this moves off the terrain and
towards the Phoenix to Tuscon urban corridor. The initial tendency
will be for convection to focus in the terrain areas, likely
growing in coverage and intensity. If a strong enough outflow can
push south out of this activity then we could see convection move
off the terrain and into the lower elevations/urban areas. If this
happens the strong southerly flow will support=20
backbuilding/training and an increased flash flood risk. HREF and=20
REFS probabilities support 2-4" rainfall totals where this training
is able to persist. However still unclear whether these totals are
able to move southward out of the higher terrain...but there is=20
certainly some potential for this scenario.

Chenard

...Previous Discussion...

...Southwest...
Numerous showers and thunderstorms are expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico, which should occur primarily during the
afternoon and evening hours. An upper low should slow to a crawl
across southeast California. Precipitable water values should
remain as high as 1.25-1.5" in spots. ML CAPE values of 2000-3000
J/kg are possible as available moisture interacts with the cold
pool aloft. A Slight Risk was maintained across parts of Arizona
and New Mexico, but it could be higher end Slight Risk. Hourly rain
amounts to 2" with local totals to 4" are possible where cells
merge and/or train.


...Southeast...
A boundary will remain in place as a cold low forms near the base
of an upper level trough, a feature that lingers for a while near
the Southern Appalachians. Farther inland across the Piedmont, some
degree of upslope flow should bring some of the higher moisture
back in from the southeast. Moisture and instability lifting ahead
of the closing system will support periods of showers and storms.
Precipitable water values of up to 2" with MU CAPE of 1000+ J/kg
across the Piedmont and 2000-3000 J/kg in coastal areas are
expected, which could yield hourly rain amounts to 2.5" and local
totals to 4". As the 00z HREF and 18z REFS had their strongest
signal for 3"+ and 5"+ across far southwest VA and the western
Carolinas, a Slight Risk was added in this update, which was
coordinated with the local offices. For the time being, a Slight
Risk was left out across the coastal plain of the Carolinas as
recent dryness could make a higher incidence of flash flooding
harder to come by, which was coordinated with the coastal Carolina
offices.

Roth


Day 2
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025


...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS & NEW MEXICO...

...Southwest/Southern Rockies...
An upper low remains fixed across the Lower Colorado River while
Gulf Moisture streams into the TX Big Bend and New Mexico, moving
up the Rio Grande. Precipitable water values of 1.25-1.5" are
forecast, which when combined with 1000+ J/kg of ML CAPE could
yield hourly amounts to 2.5" and local totals to 4" where cells
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far
west TX and NM. Closer to the upper level center across the
Southwest, slow-moving convection is possible under the cold pool
aloft, with ML CAPE of 1000-2000 J/kg of instability and
precipitable water values in the Lower Desert of 1-1.25" expected.
Based on the decline of the 1000-500 hPa thickness across UT
towards 5670 meters, limited the northern extent of the Marginal
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value.


...Carolinas/Southern Mid-Atlantic States...
Divergence aloft around the eastern periphery of a cold low near
the Southern Appalachians and what is now a tropical disturbance
moving through the Bahamas as a possible tropical cyclone on
Saturday team up to maintain precipitable water values of up to
2.25" across the coastal plain, which should also see the greatest
instability, 1000-2000 J/kg. The Piedmont should see times when the
MU CAPE rises above 500 J/kg. This is a PRE-like set up for the
region, so the heavy rainfall potential has a higher upside than
usual. There has been some convergence in the model guidance QPF-
wise, and both the 00z HREF and 18z REFS had a cohesive and
agreeable enough heavy rain threat of 3"+ for a new Slight Risk
area from roughly Richmond VA south on both sides of the fall line
into eastern SC. Hourly rain amounts to 3" and local totals to 6"
are possible, which is potentially problematic anywhere within the
Slight Risk area. A higher risk level can't be ruled out in future
updates.

Roth



Day 3
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS, NEW MEXICO, & THE CAROLINAS...

Southwest/Southern Rockies...
The combination of an upper low moving to near the Four Corners, a
kicker upper level trough moving into CA, and moisture feed from
the Gulf into NM persist into Sunday. Precipitable water values
remain above 1" locally in the Desert Southwest and 1-1.25" in the
Southern High Plains. Pockets of 1000+ J/kg of ML/MU CAPE are
forecast to develop and/or persist. A Slight Risk still appears
reasonable across portions of far west TX and NM, with a broader
Marginal Risk surrounding that. The guidance appears to be trending
somewhat drier across the Great Basin, so limited the northern
extent of the Marginal Risk area when compared to continuity.


Florida northward into the Southern Mid-Atlantic States...
A system now considered a tropical disturbance over Hispaniola
should lie somewhere north of the Bahamas and east of Florida as a
possible tropical or hybrid cyclone on Sunday. The upper level
environment doesn't look kind for whatever emerges, and there are
two scenarios -- a more convective system that remains offshore
during the medium range period or a more sheared system that
attempts to occlude when it approaches landfall early next week.
The guidance is not ideal in differentiating which is correct
during these scenarios, historically.

Regardless, moisture will not be a problem regionally --
precipitable water values locally 2"+. Coastal areas will see
1000+ J/kg of ML CAPE while 250+ J/kg of MU CAPE invades portions
of VA. The guidance has slowed down the approach of the tropical
low since yesterday, but the other players in the flow pattern
remain -- the upper low near the southern Appalachians/southern
Cumberland Plateau and the front near the East Coast. A PRE- like
set up appears to be in the cards, with moisture streaming into the
front from the south. The best signal for heavy rainfall on Sunday
into early Monday appears to be in the vicinity of Myrtle Beach,
and considering previous days of rain, thought a new Slight Risk in
that area would be prudent. In theory, hourly rain amounts to 3"
should be possible, which would be most problematic should
thunderstorms merge or train.

Roth


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!_GwtI8hMddDxomy2mdbQ5a7Jw28mxmOvgJgnRRST7IMn= rctn3shEOsqMjKdYMD9N4YpuMXjZiHA_9zUgpyWnQ3QG7KE$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!_GwtI8hMddDxomy2mdbQ5a7Jw28mxmOvgJgnRRST7IMn= rctn3shEOsqMjKdYMD9N4YpuMXjZiHA_9zUgpyWnXgZhVc8$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!_GwtI8hMddDxomy2mdbQ5a7Jw28mxmOvgJgnRRST7IMn= rctn3shEOsqMjKdYMD9N4YpuMXjZiHA_9zUgpyWnlsO0fnk$=20

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FOUS30 KWBC 262026
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
426 PM EDT Fri Sep 26 2025

Day 1
Valid 16Z Fri Sep 26 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST & IN THE VICINITY OF THE CAROLINAS...

16z Update: Not many changes needed to the inherited outlook from
earlier this morning. Central to southern AZ remains the focus for
potentially locally significant flash flooding. Pretty impressive
southerly inflow/moisture transport combined with upwards of 2000
J/KG of CAPE will support a backbuilding convective threat today.
Main question will be how much of this moves off the terrain and
towards the Phoenix to Tuscon urban corridor. The initial tendency
will be for convection to focus in the terrain areas, likely
growing in coverage and intensity. If a strong enough outflow can
push south out of this activity then we could see convection move
off the terrain and into the lower elevations/urban areas. If this
happens the strong southerly flow will support
backbuilding/training and an increased flash flood risk. HREF and
REFS probabilities support 2-4" rainfall totals where this training
is able to persist. However still unclear whether these totals are
able to move southward out of the higher terrain...but there is
certainly some potential for this scenario.

Chenard

...Previous Discussion...

...Southwest...
Numerous showers and thunderstorms are expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico, which should occur primarily during the
afternoon and evening hours. An upper low should slow to a crawl
across southeast California. Precipitable water values should
remain as high as 1.25-1.5" in spots. ML CAPE values of 2000-3000
J/kg are possible as available moisture interacts with the cold
pool aloft. A Slight Risk was maintained across parts of Arizona
and New Mexico, but it could be higher end Slight Risk. Hourly rain
amounts to 2" with local totals to 4" are possible where cells
merge and/or train.


...Southeast...
A boundary will remain in place as a cold low forms near the base
of an upper level trough, a feature that lingers for a while near
the Southern Appalachians. Farther inland across the Piedmont, some
degree of upslope flow should bring some of the higher moisture
back in from the southeast. Moisture and instability lifting ahead
of the closing system will support periods of showers and storms.
Precipitable water values of up to 2" with MU CAPE of 1000+ J/kg
across the Piedmont and 2000-3000 J/kg in coastal areas are
expected, which could yield hourly rain amounts to 2.5" and local
totals to 4". As the 00z HREF and 18z REFS had their strongest
signal for 3"+ and 5"+ across far southwest VA and the western
Carolinas, a Slight Risk was added in this update, which was
coordinated with the local offices. For the time being, a Slight
Risk was left out across the coastal plain of the Carolinas as
recent dryness could make a higher incidence of flash flooding
harder to come by, which was coordinated with the coastal Carolina
offices.

Roth


Day 2
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST AND MID ATLANTIC TO SOUTHEAST...

20z Update: The Slight risk was maintained over the Mid Atlantic
with this update. The higher confidence for potential flash=20
flooding appears to be over portions of central to southeast VA.=20
This is in the vicinity of the stationary front where lower level=20 convergence should be maximized. Instability will drop off with=20
northern extent, however we should have enough instability along=20
and just north of the front to support an axis of low topped=20
convection. This activity will likely be warm rain dominant, and=20
thus efficient at producing heavy rainfall rates. The exact axis=20
remains a bit uncertain, with model solutions varying from near=20
the NC/VA border on the southern side, to DC on the northern=20
extent. At the moment the best clustering is around Richmond, but=20
there is some opportunity for that to shift a bit north or south.=20
Where this axis does set up, localized rainfall over 4" appears=20
likely. The Slight risk was expanded a bit northward over central
and eastern VA to account for this risk.

Confidence is lower on the Slight risk farther south over NC and=20
SC. Certainly plenty of moisture in place, but the coverage and=20
organization of convection is less clear. Also a possibility that=20
the cells that do form tend to move along at a fast enough clip to=20
limit the flash flood coverage. The best chance of some training=20
could be along the coastal corridor where convergence and=20
instability may be a bit stronger. Overall the flash flood risk=20
over these areas may end up staying more isolated in nature...but=20
the potential for greater coverage is still there, and so we will=20
maintain the recently introduced Slight risk area.

Over the Southwest a Slight risk area was added to portions of=20
southeast CA into southwest AZ. The upper level low will remain=20
over these areas on Saturday providing broad ascent for convective=20 development. Instability over these areas is forecast to be=20
greater Saturday than Friday, and PWs will remain well above late=20
September averages. Thus would expect to see greater convective=20
coverage than today, with heavy rainfall rates likely. The presence
of the upper low should support slow cell motions and the=20
potential for periodic cell mergers.

Chenard

...Previous Discussion...

...Southwest/Southern Rockies...
An upper low remains fixed across the Lower Colorado River while
Gulf Moisture streams into the TX Big Bend and New Mexico, moving
up the Rio Grande. Precipitable water values of 1.25-1.5" are
forecast, which when combined with 1000+ J/kg of ML CAPE could
yield hourly amounts to 2.5" and local totals to 4" where cells
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far
west TX and NM. Closer to the upper level center across the
Southwest, slow-moving convection is possible under the cold pool
aloft, with ML CAPE of 1000-2000 J/kg of instability and
precipitable water values in the Lower Desert of 1-1.25" expected.
Based on the decline of the 1000-500 hPa thickness across UT
towards 5670 meters, limited the northern extent of the Marginal
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value.


...Carolinas/Southern Mid-Atlantic States...
Divergence aloft around the eastern periphery of a cold low near
the Southern Appalachians and what is now a tropical disturbance
moving through the Bahamas as a possible tropical cyclone on
Saturday team up to maintain precipitable water values of up to
2.25" across the coastal plain, which should also see the greatest
instability, 1000-2000 J/kg. The Piedmont should see times when the
MU CAPE rises above 500 J/kg. This is a PRE-like set up for the
region, so the heavy rainfall potential has a higher upside than
usual. There has been some convergence in the model guidance QPF-
wise, and both the 00z HREF and 18z REFS had a cohesive and
agreeable enough heavy rain threat of 3"+ for a new Slight Risk
area from roughly Richmond VA south on both sides of the fall line
into eastern SC. Hourly rain amounts to 3" and local totals to 6"
are possible, which is potentially problematic anywhere within the
Slight Risk area. A higher risk level can't be ruled out in future
updates.

Roth



Day 3
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS AND NEW MEXICO...

20z Update: We did opt to remove the small Slight risk along the
SC/NC coast with this update. Most guidance suggests the heaviest
rainfall this period will remain offshore, with greater impacts
onshore beginning on day 4 (Monday into Tuesday). There is
certainly some potential for locally heavy rain along coastal
areas, but at the moment the risk appears localized in nature.=20
Thus a Marginal risk should be enough to cover this threat for=20
now and we will continue to monitor trends.

Little to no change was needed over the Southwest with this=20
update. Portions of NM into far west TX still look on track for an=20
isolated to scattered flash flood risk as mid/upper level=20
troughing moves eastward.

Chenard

...Previous Discussion...

Southwest/Southern Rockies...
The combination of an upper low moving to near the Four Corners, a
kicker upper level trough moving into CA, and moisture feed from
the Gulf into NM persist into Sunday. Precipitable water values
remain above 1" locally in the Desert Southwest and 1-1.25" in the
Southern High Plains. Pockets of 1000+ J/kg of ML/MU CAPE are
forecast to develop and/or persist. A Slight Risk still appears
reasonable across portions of far west TX and NM, with a broader
Marginal Risk surrounding that. The guidance appears to be trending
somewhat drier across the Great Basin, so limited the northern
extent of the Marginal Risk area when compared to continuity.


Florida northward into the Southern Mid-Atlantic States...
A system now considered a tropical disturbance over Hispaniola
should lie somewhere north of the Bahamas and east of Florida as a
possible tropical or hybrid cyclone on Sunday. The upper level
environment doesn't look kind for whatever emerges, and there are
two scenarios -- a more convective system that remains offshore
during the medium range period or a more sheared system that
attempts to occlude when it approaches landfall early next week.
The guidance is not ideal in differentiating which is correct
during these scenarios, historically.

Regardless, moisture will not be a problem regionally --
precipitable water values locally 2"+. Coastal areas will see
1000+ J/kg of ML CAPE while 250+ J/kg of MU CAPE invades portions
of VA. The guidance has slowed down the approach of the tropical
low since yesterday, but the other players in the flow pattern
remain -- the upper low near the southern Appalachians/southern
Cumberland Plateau and the front near the East Coast. A PRE- like
set up appears to be in the cards, with moisture streaming into the
front from the south. The best signal for heavy rainfall on Sunday
into early Monday appears to be in the vicinity of Myrtle Beach,
and considering previous days of rain, thought a new Slight Risk in
that area would be prudent. In theory, hourly rain amounts to 3"
should be possible, which would be most problematic should
thunderstorms merge or train.

Roth


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!8D-yRoqOmKEr3QqccSN0O-qwsJwkziezGu4czyd0yK3z= sMFdgvHwMhSdW5Z4oFnVwB6XT_-nxe05Uz-V0O9rWs9EfOs$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!8D-yRoqOmKEr3QqccSN0O-qwsJwkziezGu4czyd0yK3z= sMFdgvHwMhSdW5Z4oFnVwB6XT_-nxe05Uz-V0O9r3eepMfc$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!8D-yRoqOmKEr3QqccSN0O-qwsJwkziezGu4czyd0yK3z= sMFdgvHwMhSdW5Z4oFnVwB6XT_-nxe05Uz-V0O9rn4REM70$=20

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FOUS30 KWBC 270047
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
847 PM EDT Fri Sep 26 2025

Day 1
Valid 01Z Sat Sep 27 2025 - 12Z Sat Sep 27 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST & PORTIONS OF THE WESTERN CAROLINAS INTO SOUTHERN
VIRGINIA...

...01Z Update...

Few changes needed once again to both risk areas in portions of the
Southwest and Southeast. In the Southwest, while convective
coverage and intensity remains robust, overall trends are for
weakening and diminishing of the storms across the area, as much of
the instability feeding the storms is diurnally driven, so with
sunset occurring soon, that should cut off the primary energy
source of the storms. Thus, expect continued weakening and
diminishing of the storms. Nonetheless, as they remain strong,
opted to leave the risk areas largely the same and to cover the
outside potential of new development, especially near the Mexican
border.

For the Southeast, the heavy rainfall event highlighted by the ERO
is just getting started as the low-level jet increases in intensity
and convective coverage continues to increase. Thus, needed changes
were very minimal, and were mostly cutting out a small portion of
the Marginal over northwestern Georgia which is behind much of the
convection, and adding a little on the north side of both the
Slight and Marginal in Virginia to acknowledge the most recent
guidance changes suggesting some of the rain may be able to make it
that far north into southern Virginia before weakening below an
intensity of heavy rain needed to produce flash flooding.

Wegman

...Previous Discussion...

...Southwest...
Numerous showers and thunderstorms are expected across the
Southwest, especially for much of southeastern Arizona and parts of southwestern New Mexico, which should occur primarily during the
afternoon and evening hours. An upper low should slow to a crawl
across southeast California. Precipitable water values should
remain as high as 1.25-1.5" in spots. ML CAPE values of 2000-3000
J/kg are possible as available moisture interacts with the cold
pool aloft. A Slight Risk was maintained across parts of Arizona
and New Mexico, but it could be higher end Slight Risk. Hourly rain
amounts to 2" with local totals to 4" are possible where cells
merge and/or train.


...Southeast...
A boundary will remain in place as a cold low forms near the base
of an upper level trough, a feature that lingers for a while near
the Southern Appalachians. Farther inland across the Piedmont, some
degree of upslope flow should bring some of the higher moisture
back in from the southeast. Moisture and instability lifting ahead
of the closing system will support periods of showers and storms.
Precipitable water values of up to 2" with MU CAPE of 1000+ J/kg
across the Piedmont and 2000-3000 J/kg in coastal areas are
expected, which could yield hourly rain amounts to 2.5" and local
totals to 4". As the 00z HREF and 18z REFS had their strongest
signal for 3"+ and 5"+ across far southwest VA and the western
Carolinas, a Slight Risk was added in this update, which was
coordinated with the local offices. For the time being, a Slight
Risk was left out across the coastal plain of the Carolinas as
recent dryness could make a higher incidence of flash flooding
harder to come by, which was coordinated with the coastal Carolina
offices.

Roth


Day 2
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST AND MID ATLANTIC TO SOUTHEAST...

20z Update: The Slight risk was maintained over the Mid Atlantic
with this update. The higher confidence for potential flash
flooding appears to be over portions of central to southeast VA.
This is in the vicinity of the stationary front where lower level
convergence should be maximized. Instability will drop off with
northern extent, however we should have enough instability along
and just north of the front to support an axis of low topped
convection. This activity will likely be warm rain dominant, and
thus efficient at producing heavy rainfall rates. The exact axis
remains a bit uncertain, with model solutions varying from near
the NC/VA border on the southern side, to DC on the northern
extent. At the moment the best clustering is around Richmond, but
there is some opportunity for that to shift a bit north or south.
Where this axis does set up, localized rainfall over 4" appears
likely. The Slight risk was expanded a bit northward over central
and eastern VA to account for this risk.

Confidence is lower on the Slight risk farther south over NC and
SC. Certainly plenty of moisture in place, but the coverage and
organization of convection is less clear. Also a possibility that
the cells that do form tend to move along at a fast enough clip to
limit the flash flood coverage. The best chance of some training
could be along the coastal corridor where convergence and
instability may be a bit stronger. Overall the flash flood risk
over these areas may end up staying more isolated in nature...but
the potential for greater coverage is still there, and so we will
maintain the recently introduced Slight risk area.

Over the Southwest a Slight risk area was added to portions of
southeast CA into southwest AZ. The upper level low will remain
over these areas on Saturday providing broad ascent for convective
development. Instability over these areas is forecast to be
greater Saturday than Friday, and PWs will remain well above late
September averages. Thus would expect to see greater convective
coverage than today, with heavy rainfall rates likely. The presence
of the upper low should support slow cell motions and the
potential for periodic cell mergers.

Chenard

...Previous Discussion...

...Southwest/Southern Rockies...
An upper low remains fixed across the Lower Colorado River while
Gulf Moisture streams into the TX Big Bend and New Mexico, moving
up the Rio Grande. Precipitable water values of 1.25-1.5" are
forecast, which when combined with 1000+ J/kg of ML CAPE could
yield hourly amounts to 2.5" and local totals to 4" where cells
train and/or merge. Believe the risk level from continuity (Slight)
conveys the risk appropriately at this time for portions of far
west TX and NM. Closer to the upper level center across the
Southwest, slow-moving convection is possible under the cold pool
aloft, with ML CAPE of 1000-2000 J/kg of instability and
precipitable water values in the Lower Desert of 1-1.25" expected.
Based on the decline of the 1000-500 hPa thickness across UT
towards 5670 meters, limited the northern extent of the Marginal
Risk to southern UT which is about the northern extent of the 0.75" precipitable water value.


...Carolinas/Southern Mid-Atlantic States...
Divergence aloft around the eastern periphery of a cold low near
the Southern Appalachians and what is now a tropical disturbance
moving through the Bahamas as a possible tropical cyclone on
Saturday team up to maintain precipitable water values of up to
2.25" across the coastal plain, which should also see the greatest
instability, 1000-2000 J/kg. The Piedmont should see times when the
MU CAPE rises above 500 J/kg. This is a PRE-like set up for the
region, so the heavy rainfall potential has a higher upside than
usual. There has been some convergence in the model guidance QPF-
wise, and both the 00z HREF and 18z REFS had a cohesive and
agreeable enough heavy rain threat of 3"+ for a new Slight Risk
area from roughly Richmond VA south on both sides of the fall line
into eastern SC. Hourly rain amounts to 3" and local totals to 6"
are possible, which is potentially problematic anywhere within the
Slight Risk area. A higher risk level can't be ruled out in future
updates.

Roth



Day 3
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF FAR
WEST TEXAS AND NEW MEXICO...

20z Update: We did opt to remove the small Slight risk along the
SC/NC coast with this update. Most guidance suggests the heaviest
rainfall this period will remain offshore, with greater impacts
onshore beginning on day 4 (Monday into Tuesday). There is
certainly some potential for locally heavy rain along coastal
areas, but at the moment the risk appears localized in nature.
Thus a Marginal risk should be enough to cover this threat for
now and we will continue to monitor trends.

Little to no change was needed over the Southwest with this
update. Portions of NM into far west TX still look on track for an
isolated to scattered flash flood risk as mid/upper level
troughing moves eastward.

Chenard

...Previous Discussion...

Southwest/Southern Rockies...
The combination of an upper low moving to near the Four Corners, a
kicker upper level trough moving into CA, and moisture feed from
the Gulf into NM persist into Sunday. Precipitable water values
remain above 1" locally in the Desert Southwest and 1-1.25" in the
Southern High Plains. Pockets of 1000+ J/kg of ML/MU CAPE are
forecast to develop and/or persist. A Slight Risk still appears
reasonable across portions of far west TX and NM, with a broader
Marginal Risk surrounding that. The guidance appears to be trending
somewhat drier across the Great Basin, so limited the northern
extent of the Marginal Risk area when compared to continuity.


Florida northward into the Southern Mid-Atlantic States...
A system now considered a tropical disturbance over Hispaniola
should lie somewhere north of the Bahamas and east of Florida as a
possible tropical or hybrid cyclone on Sunday. The upper level
environment doesn't look kind for whatever emerges, and there are
two scenarios -- a more convective system that remains offshore
during the medium range period or a more sheared system that
attempts to occlude when it approaches landfall early next week.
The guidance is not ideal in differentiating which is correct
during these scenarios, historically.

Regardless, moisture will not be a problem regionally --
precipitable water values locally 2"+. Coastal areas will see
1000+ J/kg of ML CAPE while 250+ J/kg of MU CAPE invades portions
of VA. The guidance has slowed down the approach of the tropical
low since yesterday, but the other players in the flow pattern
remain -- the upper low near the southern Appalachians/southern
Cumberland Plateau and the front near the East Coast. A PRE- like
set up appears to be in the cards, with moisture streaming into the
front from the south. The best signal for heavy rainfall on Sunday
into early Monday appears to be in the vicinity of Myrtle Beach,
and considering previous days of rain, thought a new Slight Risk in
that area would be prudent. In theory, hourly rain amounts to 3"
should be possible, which would be most problematic should
thunderstorms merge or train.

Roth


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7AvIKvJLJIZP2LOUmURtuqfCv9A4DPmXZkyHDxnXJZ8q= jMPQgzk5FcDXWngtus1cdblu2L8Pzfrg18yGgoFrLMsuiUU$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7AvIKvJLJIZP2LOUmURtuqfCv9A4DPmXZkyHDxnXJZ8q= jMPQgzk5FcDXWngtus1cdblu2L8Pzfrg18yGgoFr9lKrDr4$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7AvIKvJLJIZP2LOUmURtuqfCv9A4DPmXZkyHDxnXJZ8q= jMPQgzk5FcDXWngtus1cdblu2L8Pzfrg18yGgoFrIWzM6iQ$=20

=3D =3D =3D
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FOUS30 KWBC 270831
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
431 AM EDT Sat Sep 27 2025

Day 1
Valid 12Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST AND MID-ATLANTIC...

Southwest/Southern Rockies/High Plains

A closed upper low over the Southwest will generate scattered=20
thunderstorm activity across the region and into parts of the=20
Southern High Plains/Rockies beginning this afternoon. Anomalous=20
moisture (1in+ PWAT/2-3 StD) within a bouyant environment 1000+=20
MUCAPE should yield modest rain rates of over an inch/hr,=20
especially over favorable upslope terrain. Burn Scars and slot=20
canyons will be among the most susceptible to flash flooding.

Mid-Atlantic/Southeast

An upper trough will continue supplying ample moisture (1.5-2in+=20
PWAT) and sufficient instability (500 J/Kg+) to the Mid-
Atlantic/Southeast Coastline today. Storms should develop within
the warm sector of a stationary front draped across the Southern
Appalachians and Mid-Atlantic Coast. The heaviest rainfall (1-2
in/hr rates) should focus around the aforementioned front where=20
favorable right entrance region dynamics will likely develop and=20
prolong storms during peak heating hours.


Kebede

Day 2
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
FAR WEST TEXAS, NEW MEXICO AND SOUTHWESTERN COLORADO...

Southwest/Four Corners/Southern High Plains/Rockies

The upper low in the Southwest is expected to open as it lifts=20
into the Rockies on Sunday. The threat for excessive rainfall thus=20
expands a bit around the trough as the fetch of moisture from the=20
previous day rotates around the low and into parts of the Great=20
Basin and Four Corners. Some elevated instability 500 J/Kg+ MUCAPE=20
could generate 0.5-1.5 in/hr rates, especially over parts of New=20
Mexico, where a slight risk is in effect. Antecedent rainfall from=20
Saturday should lower FFGs, making soils more vulnerable to flash=20
flooding. Slot canyons, dry washes and upslope areas will likely be
the most susceptible to runoff.

Southeast

Guidance continues to trend farther away from the Southeast Coast
with the axis of substantial QPF associated with a tropical=20
cyclone moving through the Bahamas at the beginning of the day 2=20
period (Sunday morning). Given the uncertainty of the system's=20
track, it's difficult to say with any confidence if/where the most=20
impactful rainfall will occur, thus a broad marginal is in place=20
from the Outer Banks down to Miami for now.


Kebede

Day 3
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHEAST AND MID-ATLANTIC...

Southeast/Mid-Atlantic

Tropical moisture arrives along the Southeast/Mid-Atlantic Coast=20
on Monday ahead of the associated cyclone, which is currently=20
forecast to be east of Georgia by Tuesday morning. Current=20
deterministic guidance has between 2-4 inches of rainfall occurring
along the Carolina Coast with isolated higher amounts. Models are=20
trending away from the coast with the cyclone's track, which is=20
reflected in a decreasing QPF trend with this cycle as well.

Northern California/Southwest Oregon

A deep East Pacific trough will bring broad diffluent flow aloft=20
over the Northwest Coast beginning Monday morning. Scattered=20
showers and thunderstorms may develop along the leading edge of a=20
surface front, where the presence of weak instability (350 J/Kg
MUCAPE) and modest moisture (~1 in. PWAT) could produce localized=20
flash flooding along the northern California/southwest Oregon
Coasts and inland into the Southern Cascades and northern Sierra.


Kebede


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9AScklAg2iERZHfLXW1ILyO2KW8JRkmC_4fDKOUUKDXR= 5EhVqu0on3ilRiGJ0dnOyGTY9MrIvhovEj_B2RuxeedEUFM$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9AScklAg2iERZHfLXW1ILyO2KW8JRkmC_4fDKOUUKDXR= 5EhVqu0on3ilRiGJ0dnOyGTY9MrIvhovEj_B2RuxGOP8I0w$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9AScklAg2iERZHfLXW1ILyO2KW8JRkmC_4fDKOUUKDXR= 5EhVqu0on3ilRiGJ0dnOyGTY9MrIvhovEj_B2RuxwewnExA$=20

=3D =3D =3D
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FOUS30 KWBC 271549
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1149 AM EDT Sat Sep 27 2025

Day 1
Valid 16Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST AND MID-ATLANTIC...

...Desert Southwest, Four Corners, and Southern Rockies...
An anomalous upper low (700-500mb heights falling beneath the 10th
percentile from the CFSR climatology) will slowly fill today as it
pivots slowly over the low deserts of CA/AZ. Downstream of this=20
feature, confluent low and mid level flow will push northward out=20
of the Baja region of Mexico, leading to a surge of PWs reaching as
high as 1.25 inches in southern CA/AZ, and as high as 0.75 inches=20
into UT, around the 90th percentile for the date according to the=20
SPC sounding climatology. Farther east, and somewhat displaced from
the upper low, a secondary surge in moisture will lift out of the=20
Rio Grande Valley, surging PWs to around the 90th percentile as=20
well into southern NM. This moisture will overlap with increasing=20 instability (MUCAPE 500-1000 J/kg) to result in widespread showers=20
and thunderstorms today, first beneath the upper low through late=20
morning, and then expanding across a much larger region during peak
heating this aftn/eve.

In general, convection that develops today will move steadily
north/northwest in the vicinity of the upper low, with 0-6km mean
winds progged to be 10-15kts. This suggests that storms should be
generally progressive outside of terrain influences during
development, but aligned propagation vectors in the cyclonic regime
will allow for repeating rounds of cells in some areas. With rain=20
rates progged by both the HREF neighborhood probabilities and the=20
UA HRRR-forced WRF to potentially reach 0.5-1.0"/hr, this could
result in stripes of 1 to as much as 3 inches of rainfall, leading
to scattered instances of flash flooding.=20

The inherited risk areas were still well supported by the latest
guidance suite, so only minor adjustments were made to the previous
outlook.


...Mid-Atlantic States and Coastal Southeast...
A mid-level longwave trough anchored just inland from the=20
Southeast Coast and aligned into the Ohio Valley will maintain=20
intensity today, shedding vorticity lobes and accompanying weak=20
impulses northeast through the region. At the surface, a wavy front
will meander in the vicinity, with multiple low-pressures rippling
along it in response to the mid-level shortwaves. The entire area=20
will embedded within favorable thermodynamics for convection (PWS=20
1.5-2.0 inches, locally above the 97th percentile according to=20
NAEFS, overlapped with MUCAPE around 750 J/kg), with freezing=20
levels of 13,000-14,000 ft supporting efficient warm rain processes
this aftn.

It is likely that thunderstorms will become widespread, especially
during the peak diurnal cycle, and the HREF neighborhood
probabilities for 2"/hr reach as high as 30-40%. While in general
FFG exceedance probabilities are modest at 10-20%, there are
pockets of much higher probabilities (up to 40%) across the
Tidewater region of VA where a wave of low pressure and enhanced
bulk shear will help organize thunderstorms a bit more
significantly (and some of this is already ongoing, please see WPC
Metwatch #1145 for more information). Here, FFG is also=20
compromised below most adjacent areas, and the CSU First Guess=20
Field suggests a higher- end SLGT risk today. So while in general=20
flash flood instances should be pretty widely scattered, some=20
locally more numerous impacts are possible in southeast VA through=20
this evening.


Weiss

Day 2
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
FAR WEST TEXAS, NEW MEXICO AND SOUTHWESTERN COLORADO...

Southwest/Four Corners/Southern High Plains/Rockies

The upper low in the Southwest is expected to open as it lifts
into the Rockies on Sunday. The threat for excessive rainfall thus
expands a bit around the trough as the fetch of moisture from the
previous day rotates around the low and into parts of the Great
Basin and Four Corners. Some elevated instability 500 J/Kg+ MUCAPE
could generate 0.5-1.5 in/hr rates, especially over parts of New
Mexico, where a slight risk is in effect. Antecedent rainfall from
Saturday should lower FFGs, making soils more vulnerable to flash
flooding. Slot canyons, dry washes and upslope areas will likely be
the most susceptible to runoff.

Southeast

Guidance continues to trend farther away from the Southeast Coast
with the axis of substantial QPF associated with a tropical
cyclone moving through the Bahamas at the beginning of the day 2
period (Sunday morning). Given the uncertainty of the system's
track, it's difficult to say with any confidence if/where the most
impactful rainfall will occur, thus a broad marginal is in place
from the Outer Banks down to Miami for now.


Kebede

Day 3
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHEAST AND MID-ATLANTIC...

Southeast/Mid-Atlantic

Tropical moisture arrives along the Southeast/Mid-Atlantic Coast
on Monday ahead of the associated cyclone, which is currently
forecast to be east of Georgia by Tuesday morning. Current
deterministic guidance has between 2-4 inches of rainfall occurring
along the Carolina Coast with isolated higher amounts. Models are
trending away from the coast with the cyclone's track, which is
reflected in a decreasing QPF trend with this cycle as well.

Northern California/Southwest Oregon

A deep East Pacific trough will bring broad diffluent flow aloft
over the Northwest Coast beginning Monday morning. Scattered
showers and thunderstorms may develop along the leading edge of a
surface front, where the presence of weak instability (350 J/Kg
MUCAPE) and modest moisture (~1 in. PWAT) could produce localized
flash flooding along the northern California/southwest Oregon
Coasts and inland into the Southern Cascades and northern Sierra.


Kebede


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7GPR1s8hplDuXbIQfWREJlwUHl8acGKQqzJZ0H5Gxvn1= d2mRI00UW5yDCVVoW-9NADub3B_Lb1T17sFZmXmGdWcuS-w$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7GPR1s8hplDuXbIQfWREJlwUHl8acGKQqzJZ0H5Gxvn1= d2mRI00UW5yDCVVoW-9NADub3B_Lb1T17sFZmXmGpt7A6d8$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7GPR1s8hplDuXbIQfWREJlwUHl8acGKQqzJZ0H5Gxvn1= d2mRI00UW5yDCVVoW-9NADub3B_Lb1T17sFZmXmGExbtgHo$=20

=3D =3D =3D
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FOUS30 KWBC 271924
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
324 PM EDT Sat Sep 27 2025

Day 1
Valid 16Z Sat Sep 27 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST AND MID-ATLANTIC...

...Desert Southwest, Four Corners, and Southern Rockies...
An anomalous upper low (700-500mb heights falling beneath the 10th
percentile from the CFSR climatology) will slowly fill today as it
pivots slowly over the low deserts of CA/AZ. Downstream of this
feature, confluent low and mid level flow will push northward out
of the Baja region of Mexico, leading to a surge of PWs reaching as
high as 1.25 inches in southern CA/AZ, and as high as 0.75 inches
into UT, around the 90th percentile for the date according to the
SPC sounding climatology. Farther east, and somewhat displaced from
the upper low, a secondary surge in moisture will lift out of the
Rio Grande Valley, surging PWs to around the 90th percentile as
well into southern NM. This moisture will overlap with increasing
instability (MUCAPE 500-1000 J/kg) to result in widespread showers
and thunderstorms today, first beneath the upper low through late
morning, and then expanding across a much larger region during peak
heating this aftn/eve.

In general, convection that develops today will move steadily
north/northwest in the vicinity of the upper low, with 0-6km mean
winds progged to be 10-15kts. This suggests that storms should be
generally progressive outside of terrain influences during
development, but aligned propagation vectors in the cyclonic regime
will allow for repeating rounds of cells in some areas. With rain
rates progged by both the HREF neighborhood probabilities and the
UA HRRR-forced WRF to potentially reach 0.5-1.0"/hr, this could
result in stripes of 1 to as much as 3 inches of rainfall, leading
to scattered instances of flash flooding.

The inherited risk areas were still well supported by the latest
guidance suite, so only minor adjustments were made to the previous
outlook.


...Mid-Atlantic States and Coastal Southeast...
A mid-level longwave trough anchored just inland from the
Southeast Coast and aligned into the Ohio Valley will maintain
intensity today, shedding vorticity lobes and accompanying weak
impulses northeast through the region. At the surface, a wavy front
will meander in the vicinity, with multiple low-pressures rippling
along it in response to the mid-level shortwaves. The entire area
will embedded within favorable thermodynamics for convection (PWS
1.5-2.0 inches, locally above the 97th percentile according to
NAEFS, overlapped with MUCAPE around 750 J/kg), with freezing
levels of 13,000-14,000 ft supporting efficient warm rain processes
this aftn.

It is likely that thunderstorms will become widespread, especially
during the peak diurnal cycle, and the HREF neighborhood
probabilities for 2"/hr reach as high as 30-40%. While in general
FFG exceedance probabilities are modest at 10-20%, there are
pockets of much higher probabilities (up to 40%) across the
Tidewater region of VA where a wave of low pressure and enhanced
bulk shear will help organize thunderstorms a bit more
significantly (and some of this is already ongoing, please see WPC
Metwatch #1145 for more information). Here, FFG is also
compromised below most adjacent areas, and the CSU First Guess
Field suggests a higher- end SLGT risk today. So while in general
flash flood instances should be pretty widely scattered, some
locally more numerous impacts are possible in southeast VA through
this evening.


Weiss

Day 2
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
FAR WEST TEXAS AND NEW MEXICO...

...Great Basin through the Southern Rockies...
The closed low over the Low Deserts on D1 will gradually open and
fill during Sunday while meandering slowly northeast such that the
primary trough axis is positioned over the Four Corners by 12Z
Monday. Despite this weakening, pronounced height falls and
periodic PVA from weak embedded impulses will maintain broad ascent
from the Great Basin through the Southern Rockies. At the same
time, downstream southerly flow ahead of the trough axis will
continue to manifest as a surge of elevated PWs, with widespread PW
anomalies from the NAEFS reaching the 97th to 99th percentiles.

This broad southerly flow combined with the lowering heights aloft
will also produce elevated MUCAPE of 500-750 J/kg across most of
this area, with locally enhanced instability above 1000 J/kg over
NM. This setup will support scattered to widespread convection as
suggested by available CAMs simulated reflectivity, with rain rates
potentially reaching 1"/hr at times. Mean 0-6km winds Sunday should
again be steady out of the south at 10-15 kts, although aligned
propagation vectors could result in some repeating/training,
especially across New Mexico. The inherited risk areas were
adjusted for new guidance, but changes were primarily cosmetic.


...Southeast Coast...
Concern on Sunday turns towards Tropical Depression Nine and its
evolution as it starts to lift slowly northward from the Bahamas
while strengthening. While there continues to be quite a bit of
model uncertainty, the general model trends have been for a slower
progression of this system, with very dry air likely positioned
just to its west as reflected by 750-500mb RH fields.=20

This suggests that precipitation may be a bit slower to move=20
onshore from the FL Peninsula into the Carolinas, but as Nine=20
deepens and the subsequent 850mb winds to the north intensify, the=20 accompanying strengthening cyclonic flow will transport impressive=20
tropical moisture westward and onshore, with PWs likely reaching=20
above 2" from Cape Fear southward through the Space Coast. As
tropical rain showers move onshore, they will be extremely
efficient, with rain rates likely reaching 2-3"/hr. These showers
will repeatedly generate offshore and then train onshore, so right
along the immediate coast where sufficient instability and
moistening can occur, total rainfall could exceed 3", especially
across Florida, as reflected by HREF probabilities exceeding 40%.
Of course, any additional trends west or slower in the track of
Nine could enhance this rainfall, and locally higher totals are
expected.

The inherited MRGL risk was trimmed closer to the coast, especially
across the Carolinas, with this update, with additional, but=20
minimal cosmetic adjustments over the Florida Peninsula also made
with this update.


Weiss

Day 3
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE COASTAL
PLAIN FROM NORTH CAROLINA THROUGH THE CENTRAL FLORIDA PENINSULA...

...Southeast and Mid-Atlantic...
All attention will be on Tropical Depression Nine, which is
forecast by NHC to be a strong Tropical Storm or Cat 1 Hurricane on
Monday as it lifts slowly northward from the Bahamas. While
guidance has been slowly converging on a solution that brings the
storm to a stall east of the GA/SC coast by the end of D3, there is
still considerable spread in the ensembles. Staying close to the
NHC track brings heavy rainfall D3 from the Space Coast of Florida
northward into Southeast North Carolina. The exact track and
intensity of Nine will determine where the greatest moisture
convergence will occur to create the heaviest rainfall amounts, but
anywhere along and north of the track will likely receive training
tropical showers with 2-3"/hr rain rates. The heaviest rain still
appears to be confined to the immediate coast due to dry air to the
west, but as the column slowly saturates in response to persistent
and increasing moist advection on strengthening onshore 850mb flow,
heavy rain will eventually spread inland, especially into SC and
NC. While the inherited SLGT risk was trimmed to the south a bit
over NC and expanded along the eastern coast of the FL Peninsula
with this update, in general, changes were minimal due to
continuing track uncertainty.


...Northern California/Southwest Oregon...
An impressive trough will push eastward across the Pacific Monday,
reaching the coast and angling onshore by 12Z Tuesday. This will
drive a frontal system onshore, and the resulting low-level
convergence overlapped by a modestly coupled jet structure will
provide plentiful ascent for heavy rainfall along the coast of
northern CA/southern OR D3. Moisture transport will become
impressive ahead of the front as reflected by high probabilities
(70-80%) for IVT exceeding 500 kg/m/s from both the ECENS and GEFS
ensembles, pushing PWs to above 1 inch on increasing southerly
850mb inflow. Where this moisture overlaps with sufficient
instability (progs suggest at least 250 J/kg MUCAPE) it will result
in periods of moderate to heavy rainfall with rates of
0.25-0.5"/hr which may be sufficient for at least localized impacts
in vulnerable terrain, especially where training or enhanced
convergence along terrain features can produce more than 1 inch of
rainfall.


Weiss


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!5SAbkh4zNICpaHd6TpGKcYsey254oPT-WO4_kxPGpkCc= nxSOYBx9Nzlz29keLykPRIfXX_2W9snq7GcHwtsWFyCYFIc$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!5SAbkh4zNICpaHd6TpGKcYsey254oPT-WO4_kxPGpkCc= nxSOYBx9Nzlz29keLykPRIfXX_2W9snq7GcHwtsWjZnSZyM$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!5SAbkh4zNICpaHd6TpGKcYsey254oPT-WO4_kxPGpkCc= nxSOYBx9Nzlz29keLykPRIfXX_2W9snq7GcHwtsW1R4SeSw$=20

=3D =3D =3D
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FOUS30 KWBC 280057
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
857 PM EDT Sat Sep 27 2025

Day 1
Valid 01Z Sun Sep 28 2025 - 12Z Sun Sep 28 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
THE SOUTHWEST...

...Southwest...
A Slight risk was maintained across portions of southeast CA into
western AZ. Isolated to scattered instances of flash flooding
continue this evening. Still generally expect to see the coverage
and intensity of convection decrease overnight, although with
lingering instability and the mid level low overhead we could see
at least some localized areas of heavier convection continue.

The Slight risk was removed over NM with this update. Still expect
to see some convection overnight, and localized instances of flash
flooding are still possible. However, activity has generally=20
underperformed so far today, and with instability lower here=20
compared to farther west, generally think the flash flood risk is=20
isolated enough to warrant just the Marginal risk.

...East Coast...
A Marginal risk was maintained in the vicinity of the Delmarva
where low topped convection will support efficient warm rain
processes. Overall not expecting much in the way of a flood=20
threat, but heavy rates could result in a localized risk.

Slow moving convection near the mid/upper vort energy will
continue to support an isolated flash flood risk over portions of=20
southwest VA and central NC. Overall the expectation is for this=20
activity to decrease in coverage/intensity going forward...but=20
models have not had a great handle on this convection and thus=20
another instance or two of flash flooding can not be ruled out.

Increasing easterly flow well north of Tropical Depression Nine=20
may help locally enhance convergence along the east coast of FL=20
tonight into Sunday morning. Low confidence on these details, but=20
if heavier convection is able to develop then a localized urban=20
flash flood risk is a possibility.

Chenard


Day 2
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS OF
FAR WEST TEXAS AND NEW MEXICO...

...Great Basin through the Southern Rockies...
The closed low over the Low Deserts on D1 will gradually open and
fill during Sunday while meandering slowly northeast such that the
primary trough axis is positioned over the Four Corners by 12Z
Monday. Despite this weakening, pronounced height falls and
periodic PVA from weak embedded impulses will maintain broad ascent
from the Great Basin through the Southern Rockies. At the same
time, downstream southerly flow ahead of the trough axis will
continue to manifest as a surge of elevated PWs, with widespread PW
anomalies from the NAEFS reaching the 97th to 99th percentiles.

This broad southerly flow combined with the lowering heights aloft
will also produce elevated MUCAPE of 500-750 J/kg across most of
this area, with locally enhanced instability above 1000 J/kg over
NM. This setup will support scattered to widespread convection as
suggested by available CAMs simulated reflectivity, with rain rates
potentially reaching 1"/hr at times. Mean 0-6km winds Sunday should
again be steady out of the south at 10-15 kts, although aligned
propagation vectors could result in some repeating/training,
especially across New Mexico. The inherited risk areas were
adjusted for new guidance, but changes were primarily cosmetic.


...Southeast Coast...
Concern on Sunday turns towards Tropical Depression Nine and its
evolution as it starts to lift slowly northward from the Bahamas
while strengthening. While there continues to be quite a bit of
model uncertainty, the general model trends have been for a slower
progression of this system, with very dry air likely positioned
just to its west as reflected by 750-500mb RH fields.

This suggests that precipitation may be a bit slower to move
onshore from the FL Peninsula into the Carolinas, but as Nine
deepens and the subsequent 850mb winds to the north intensify, the
accompanying strengthening cyclonic flow will transport impressive
tropical moisture westward and onshore, with PWs likely reaching
above 2" from Cape Fear southward through the Space Coast. As
tropical rain showers move onshore, they will be extremely
efficient, with rain rates likely reaching 2-3"/hr. These showers
will repeatedly generate offshore and then train onshore, so right
along the immediate coast where sufficient instability and
moistening can occur, total rainfall could exceed 3", especially
across Florida, as reflected by HREF probabilities exceeding 40%.
Of course, any additional trends west or slower in the track of
Nine could enhance this rainfall, and locally higher totals are
expected.

The inherited MRGL risk was trimmed closer to the coast, especially
across the Carolinas, with this update, with additional, but
minimal cosmetic adjustments over the Florida Peninsula also made
with this update.


Weiss

Day 3
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS THE COASTAL
PLAIN FROM NORTH CAROLINA THROUGH THE CENTRAL FLORIDA PENINSULA...

...Southeast and Mid-Atlantic...
All attention will be on Tropical Depression Nine, which is
forecast by NHC to be a strong Tropical Storm or Cat 1 Hurricane on
Monday as it lifts slowly northward from the Bahamas. While
guidance has been slowly converging on a solution that brings the
storm to a stall east of the GA/SC coast by the end of D3, there is
still considerable spread in the ensembles. Staying close to the
NHC track brings heavy rainfall D3 from the Space Coast of Florida
northward into Southeast North Carolina. The exact track and
intensity of Nine will determine where the greatest moisture
convergence will occur to create the heaviest rainfall amounts, but
anywhere along and north of the track will likely receive training
tropical showers with 2-3"/hr rain rates. The heaviest rain still
appears to be confined to the immediate coast due to dry air to the
west, but as the column slowly saturates in response to persistent
and increasing moist advection on strengthening onshore 850mb flow,
heavy rain will eventually spread inland, especially into SC and
NC. While the inherited SLGT risk was trimmed to the south a bit
over NC and expanded along the eastern coast of the FL Peninsula
with this update, in general, changes were minimal due to
continuing track uncertainty.


...Northern California/Southwest Oregon...
An impressive trough will push eastward across the Pacific Monday,
reaching the coast and angling onshore by 12Z Tuesday. This will
drive a frontal system onshore, and the resulting low-level
convergence overlapped by a modestly coupled jet structure will
provide plentiful ascent for heavy rainfall along the coast of
northern CA/southern OR D3. Moisture transport will become
impressive ahead of the front as reflected by high probabilities
(70-80%) for IVT exceeding 500 kg/m/s from both the ECENS and GEFS
ensembles, pushing PWs to above 1 inch on increasing southerly
850mb inflow. Where this moisture overlaps with sufficient
instability (progs suggest at least 250 J/kg MUCAPE) it will result
in periods of moderate to heavy rainfall with rates of
0.25-0.5"/hr which may be sufficient for at least localized impacts
in vulnerable terrain, especially where training or enhanced
convergence along terrain features can produce more than 1 inch of
rainfall.


Weiss


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!-6rocvidYNaM1uOSopYxalkmeDx6R8ZniWv4HMxaBGi0= UHiWneK-G6emfOSJa5NE-UMoQlkYTc4XHkMuVF1yUL4CsZQ$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!-6rocvidYNaM1uOSopYxalkmeDx6R8ZniWv4HMxaBGi0= UHiWneK-G6emfOSJa5NE-UMoQlkYTc4XHkMuVF1yoj88jXE$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!-6rocvidYNaM1uOSopYxalkmeDx6R8ZniWv4HMxaBGi0= UHiWneK-G6emfOSJa5NE-UMoQlkYTc4XHkMuVF1yu09dmxA$=20

=3D =3D =3D
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FOUS30 KWBC 280829
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
429 AM EDT Sun Sep 28 2025

Day 1
Valid 01Z Sun Sep 28 2025 - 12Z Sun Sep 28 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS MUCH OF NEW
MEXICO AND PORTIONS OF FAR WESTERN TEXAS/SOUTHERN COLORADO...

...Four Corners/Southwest...
An upper trough centered over the Southwest will continue=20
directing mid-level vortices northward through the Four Corners=20
region today. Moisture from Tropical Cyclone Narda in the East=20
Pacific will continue surging north into the Four Corners, where=20
scattered showers and thunderstorms are likely to proliferate throughout
the day. PWATs between 1-1.5 inches within the right entrance=20
region of the upper jet and modest instability around 500-1000+=20
J/Kg (MLCAPE) could yield rain rates between 0.5-1 in./hr.,=20
especially where the slight risk is currently drawn. Burn scars,=20
scars slot canyons and upslope areas within the risk areas are=20
especially vulnerable to flash flooding.=20

HREF's neighborhood exceedance probabilities of 2 in. in 24 hours=20
are between 25-50% while EAS probabilities of exceeding 0.5 in.=20
hover around 20-40% within the depicted slight risk area.


...Southeast...
An upper trough will pivot eastward over the Southeast while=20
moisture from T.C. Nine continues surging northward toward the=20
Southeast Coast. Current guidance keeps the axis of heaviest QPF=20
offshore, but enough moisture may propagate far enough north and=20
west to interact with a surface front draped along the coast and=20
produce localized excessive rainfall. HREF EAS exceedance=20
probabilities of 1 inch in 24 hours are between 5-15% along much=20
of the Carolina Coast today, which supports the marginal risk area
depicted.

Kebede

Day 2
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
CAROLINA COAST...

...Southeast...
Guidance continue to depict T.C. Nine propagating north toward the
Southeast Coast on Monday, while a surface front draped along the=20
coast acts as the focus for heavy rainfall. QPF has trended=20
downward given slowing trends in the track of T.C. Nine on Monday.
The GFS suite in particular diverges most from the Canadian and=20
Euro suites when depicting the system's slower forward motion.=20
Despite this, enough moisture should work its way into the coast
and interact with the surface front to generate scattered thunderstorms. There'll be enough moisture (1.5-2.5in PWATs) and instability=20
(1000+ J/KG MUCAPE) present to support rainfall rates in excess of
1 in./hr..

...Northern California/Great Basin/Southern Cascades...
An upper low centered over the East Pacific will send mid-level=20
vortices into the West Coast on Monday. Pacific moisture may=20
collide with the remnant tropical moisture from Narda to produce=20
heavy rainfall from northern California into the Great Basin.=20
Synoptic forcing provided by a strong surface cold front should=20
focus PWATs in the range of 0.75-1.25 in. to produce quarter inch=20
rain rates along the immediate coast. More robust instability over=20
the Great Basin should yield higher rain rates between 0.5-1=20
in./hr. in some areas. Upslope enhancement may generate higher=20
totals in parts of the terrain.

Kebede

Day 3
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
CAROLINA COAST...

...Southeast...
The inherited marginal and slight risk areas along the Southeast=20
Coast were downsized based on trends in the guidance suggesting=20
T.C. Nine's hard turn out to sea on Tuesday. Despite the resulting
smaller QPF footprint than previous cycles, the flash flood risk=20
remains. Instability will be negligible (less than 500 J/Kg=20
MUCAPE), which supports the possibility that the flood threat will be
due to runoff over saturated soils from Sunday and Monday's=20
rainfall. Exceedance probabilities of over 2 inches is over 10% in
the 00z ECENS/CMCE, while below 10% in the GEFS along the=20
immediate Carolina Coast.

Kebede


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9CYiVEneZMixDw3UL5rD9-gc3wknJ8S7ajYNrYVy8laI= -OdCwgYjk8PgU-OpCcCOUI1bgfGEhDQ4uNQSes0gJ8-bKFE$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9CYiVEneZMixDw3UL5rD9-gc3wknJ8S7ajYNrYVy8laI= -OdCwgYjk8PgU-OpCcCOUI1bgfGEhDQ4uNQSes0gDqUrKE0$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9CYiVEneZMixDw3UL5rD9-gc3wknJ8S7ajYNrYVy8laI= -OdCwgYjk8PgU-OpCcCOUI1bgfGEhDQ4uNQSes0g4as4coA$=20

=3D =3D =3D
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FOUS30 KWBC 281556
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
1156 AM EDT Sun Sep 28 2025

Day 1
Valid 12Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS MUCH OF NEW
MEXICO AND PORTIONS OF FAR WESTERN TEXAS/SOUTHERN COLORADO, AS WELL
AS, PORTIONS OF NORTHWEST ARIZONA...

16z update:
New Mexico/West TX Panhandle: Mid-level sub-tropical moisture=20
continues to stream northward through the leading height-=20
falls/outer edge of deep-layer cyclone across Western TX Panhandle=20
through the Sacramento Mountains and points northward. Reinforcing=20
surface to boundary layer moisture return through up- slope process
will maintain 1-1.25" total PWats. Embedded mid-level impulses=20
through the large base of the cyclone will allow for multiple=20
rounds across S NM/W TX Panhandle to maintain the Slight Risk.=20

Southwest (N AZ): Near the northwest edge of the inner core of the
upper- low in NW AZ, there remains a slightly enhanced signal for=20
increased rainfall rates/totals per HREF probs and 12z Hi-Res CAMs.
Enough so to be highlighted with 20-40% of 2"+ through 12z . Given
slow cell motions and position relative to the deeper cyclone and=20
fairly saturated soils over the last few days is sufficient to=20
highlight a small separate Slight Risk area.=20

Further North (ID/WY): A subtle vorticity center is lifting north=20
through the northern Great Basin toward the Snake River Plain; Hi-
Res CAMs indicate slightly better instability from 250-500 J/kg may
allow for scattered mountain anchored convection through the
afternoon/evening trending northward toward Tetons and Ranges=20
across SE ID/far W WY. Enough so, to expand the Marginal Risk=20
northward to encompass the increase in potential.=20

Southeast: Forecast remains on track, solid onshore flow and
enhanced deep layer moisture values over 2-2.25 and some weak
500-1000 J/kg of CAPE should allow for scattered thunderstorm
activity capable of locally intense rates. Only minor adjustments
were made to the Marginal Risk line.=20

Gallina

~~~~Prior Discussion~~~~~

...Four Corners/Southwest...
An upper trough centered over the Southwest will continue
directing mid-level vortices northward through the Four Corners
region today. Moisture from Tropical Cyclone Narda in the East
Pacific will continue surging north into the Four Corners, where
scattered showers and thunderstorms are likely to proliferate throughout
the day. PWATs between 1-1.5 inches within the right entrance
region of the upper jet and modest instability around 500-1000+
J/Kg (MLCAPE) could yield rain rates between 0.5-1 in./hr.,
especially where the slight risk is currently drawn. Burn scars,
scars slot canyons and upslope areas within the risk areas are
especially vulnerable to flash flooding.

HREF's neighborhood exceedance probabilities of 2 in. in 24 hours
are between 25-50% while EAS probabilities of exceeding 0.5 in.
hover around 20-40% within the depicted slight risk area.


...Southeast...
An upper trough will pivot eastward over the Southeast while
moisture from T.C. Nine continues surging northward toward the
Southeast Coast. Current guidance keeps the axis of heaviest QPF
offshore, but enough moisture may propagate far enough north and
west to interact with a surface front draped along the coast and
produce localized excessive rainfall. HREF EAS exceedance
probabilities of 1 inch in 24 hours are between 5-15% along much
of the Carolina Coast today, which supports the marginal risk area
depicted.

Kebede

Day 2
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
CAROLINA COAST...

...Southeast...
Guidance continue to depict T.C. Nine propagating north toward the
Southeast Coast on Monday, while a surface front draped along the
coast acts as the focus for heavy rainfall. QPF has trended
downward given slowing trends in the track of T.C. Nine on Monday.
The GFS suite in particular diverges most from the Canadian and
Euro suites when depicting the system's slower forward motion.
Despite this, enough moisture should work its way into the coast
and interact with the surface front to generate scattered thunderstorms. There'll be enough moisture (1.5-2.5in PWATs) and instability
(1000+ J/KG MUCAPE) present to support rainfall rates in excess of
1 in./hr..

...Northern California/Great Basin/Southern Cascades...
An upper low centered over the East Pacific will send mid-level
vortices into the West Coast on Monday. Pacific moisture may
collide with the remnant tropical moisture from Narda to produce
heavy rainfall from northern California into the Great Basin.
Synoptic forcing provided by a strong surface cold front should
focus PWATs in the range of 0.75-1.25 in. to produce quarter inch
rain rates along the immediate coast. More robust instability over
the Great Basin should yield higher rain rates between 0.5-1
in./hr. in some areas. Upslope enhancement may generate higher
totals in parts of the terrain.

Kebede

Day 3
Valid 12Z Tue Sep 30 2025 - 12Z Wed Oct 01 2025

...THERE'S A SLIGHT RISK OF EXCESSIVE RAINFALL FOR PORTIONS OF THE
CAROLINA COAST...

...Southeast...
The inherited marginal and slight risk areas along the Southeast
Coast were downsized based on trends in the guidance suggesting
T.C. Nine's hard turn out to sea on Tuesday. Despite the resulting
smaller QPF footprint than previous cycles, the flash flood risk
remains. Instability will be negligible (less than 500 J/Kg
MUCAPE), which supports the possibility that the flood threat will be
due to runoff over saturated soils from Sunday and Monday's
rainfall. Exceedance probabilities of over 2 inches is over 10% in
the 00z ECENS/CMCE, while below 10% in the GEFS along the
immediate Carolina Coast.

Kebede


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!6uFAzqYdJ_L88XfT5_yzene3C0vAwFQe-dS9asUoHY2O= tb-02gXBFHsvM_b7AEC68SWxmlR637fniM7cMsFfXBYWidY$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!6uFAzqYdJ_L88XfT5_yzene3C0vAwFQe-dS9asUoHY2O= tb-02gXBFHsvM_b7AEC68SWxmlR637fniM7cMsFfs82RwyM$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!6uFAzqYdJ_L88XfT5_yzene3C0vAwFQe-dS9asUoHY2O= tb-02gXBFHsvM_b7AEC68SWxmlR637fniM7cMsFfIs1Rpx0$=20

=3D =3D =3D
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FOUS30 KWBC 281927
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
327 PM EDT Sun Sep 28 2025

Day 1
Valid 16Z Sun Sep 28 2025 - 12Z Mon Sep 29 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL ACROSS MUCH OF NEW
MEXICO AND PORTIONS OF FAR WESTERN TEXAS/SOUTHERN COLORADO, AS=20
WELL AS, PORTIONS OF NORTHWEST ARIZONA...

16z update:
New Mexico/West TX Panhandle: Mid-level sub-tropical moisture
continues to stream northward through the leading height-
falls/outer edge of deep-layer cyclone across Western TX Panhandle
through the Sacramento Mountains and points northward. Reinforcing
surface to boundary layer moisture return through up- slope process
will maintain 1-1.25" total PWats. Embedded mid-level impulses
through the large base of the cyclone will allow for multiple
rounds across S NM/W TX Panhandle to maintain the Slight Risk.

Southwest (N AZ): Near the northwest edge of the inner core of the
upper- low in NW AZ, there remains a slightly enhanced signal for
increased rainfall rates/totals per HREF probs and 12z Hi-Res CAMs.
Enough so to be highlighted with 20-40% of 2"+ through 12z . Given
slow cell motions and position relative to the deeper cyclone and
fairly saturated soils over the last few days is sufficient to
highlight a small separate Slight Risk area.

Further North (ID/WY): A subtle vorticity center is lifting north
through the northern Great Basin toward the Snake River Plain; Hi-
Res CAMs indicate slightly better instability from 250-500 J/kg may
allow for scattered mountain anchored convection through the
afternoon/evening trending northward toward Tetons and Ranges
across SE ID/far W WY. Enough so, to expand the Marginal Risk
northward to encompass the increase in potential.

Southeast: Forecast remains on track, solid onshore flow and
enhanced deep layer moisture values over 2-2.25 and some weak
500-1000 J/kg of CAPE should allow for scattered thunderstorm
activity capable of locally intense rates. Only minor adjustments
were made to the Marginal Risk line.

Gallina

~~~~Prior Discussion~~~~~

...Four Corners/Southwest...
An upper trough centered over the Southwest will continue
directing mid-level vortices northward through the Four Corners
region today. Moisture from Tropical Cyclone Narda in the East
Pacific will continue surging north into the Four Corners, where
scattered showers and thunderstorms are likely to proliferate throughout
the day. PWATs between 1-1.5 inches within the right entrance
region of the upper jet and modest instability around 500-1000+
J/Kg (MLCAPE) could yield rain rates between 0.5-1 in./hr.,
especially where the slight risk is currently drawn. Burn scars,
scars slot canyons and upslope areas within the risk areas are
especially vulnerable to flash flooding.

HREF's neighborhood exceedance probabilities of 2 in. in 24 hours
are between 25-50% while EAS probabilities of exceeding 0.5 in.
hover around 20-40% within the depicted slight risk area.


...Southeast...
An upper trough will pivot eastward over the Southeast while
moisture from T.C. Nine continues surging northward toward the
Southeast Coast. Current guidance keeps the axis of heaviest QPF
offshore, but enough moisture may propagate far enough north and
west to interact with a surface front draped along the coast and
produce localized excessive rainfall. HREF EAS exceedance
probabilities of 1 inch in 24 hours are between 5-15% along much
of the Carolina Coast today, which supports the marginal risk area
depicted.

Kebede

Day 2
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE IMMEDIATE=20
CAROLINA COASTLINE...

21z update:

...Central New Mexico...
Upper-level trough across the Southwest continues to march east-=20
northeast, filling fairly rapidly as it reaches the Four Corners in
the early forecast period. This has diminished overall wind field=20
and pushed the deeper warm conveyor/moisture plume into the Plains.
However, lingering sufficient moisture (.75"-1"), modest=20
divergence aloft at least initially,clearing for solid insolation=20
and solid lapse rates (500 J/kg) aloft will allow for potential for
stronger thunderstorms along the Sacramento Range. While the=20
overall intensity and potential for higher rates is reducing=20
relative to prior days, there is sufficient rainfall rate/total=20
signals with 12z HREF probability of 50% of 2"+ and even a small=20
15% or 3" totals across the Sacramento Range and ridge lines east=20
of the Rio Grande Valley. As such, will include a small Marginal=20
Risk area across the ridge of south-central to central New Mexico.

...Southeast...
Strong easterly onshore flow will continue and in proximity to the
coastal front, weak elevated showers and embedded convective=20
elements are expected along/downstream across the western Piedmont=20
into the foothills of the southern Appalachian Range, combined with
upslope enhancement localized 1-2" totals are possible and have=20
expanded the Marginal Risk slightly westward into the eastern=20
slopes of the Appalachians.

However, the trends for T.S. Imelda remain slow with a sharp=20
eastward turn, further shifting the QPF gradient southeastward and
offshore relative to prior cycles. However, strong confluent flow=20
in proximity to the coastal front and Gulf Stream may allow for=20
scattered thunderstorms to remain possible very close to the=20
beaches of southeast North Carolina and the South Carolina coast.=20
Higher probabilities suggest strongest rates/totals will remain=20
offshore. While there was some solid consideration for removing the
Slight Risk from this update; collaboration with the local=20
forecast offices and a few remaining solutions that bring the=20
surface rooted frontal convection further north to the coast have=20
maintained a narrow Slight Risk mainly for the coastal cities of=20
Northeast SC/Southeast NC.=20

...Northern California/Great Basin/Idaho,W Montana Rockies...
The sharp, elongated meridional trough axis has trended a bit
faster in the northern portion to allow for a slightly more evolved
wave along the frontal zone reaching far NW California Coast,
increasing duration of moderate onshore rainfall allowing for a
slight northward expansion of the Marginal Risk across SW OR.
Additionally, the upstream strong shortwave originating from
Kamchatka, rapidly advances and deepens the upstream wave and
further narrows the spacing between it and the leading wave. This
provides increased downstream divergence across the Great Basin
into the Idaho/Montana Rockies, while also strengthening the cross
Sierra Nevada flow to allow for a favorable back-building regime
across western Nevada (just east of the natural rain shadow of the
Sierra Nevada Range). Potential repeating convective elements=20
across N NV, SE OR and SW ID show an uptick in rainfall totals=20
with even some HREF probabilities of 1"/hr toward late evening,=20
early overnight period. Instability is a bit better along the
upwind edge reaching near 1000 J/kg across the Great Basin enough=20
that 2"/12hr probabilities are nearing 50% in central NV. At this=20
time, confidence is increasing, but not enough to delineate any=20
Slight Risk area at this time.=20

Gallina


~~~~Prior Discussion~~~~

...Southeast...
Guidance continue to depict T.C. Nine propagating north toward the
Southeast Coast on Monday, while a surface front draped along the
coast acts as the focus for heavy rainfall. QPF has trended
downward given slowing trends in the track of T.C. Nine on Monday.
The GFS suite in particular diverges most from the Canadian and
Euro suites when depicting the system's slower forward motion.
Despite this, enough moisture should work its way into the coast
and interact with the surface front to generate scattered thunderstorms. There'll be enough moisture (1.5-2.5in PWATs) and instability
(1000+ J/KG MUCAPE) present to support rainfall rates in excess of
1 in./hr..

...Northern California/Great Basin/Southern Cascades...
An upper low centered over the East Pacific will send mid-level
vortices into the West Coast on Monday. Pacific moisture may
collide with the remnant tropical moisture from Narda to produce
heavy rainfall from northern California into the Great Basin.
Synoptic forcing provided by a strong surface cold front should
focus PWATs in the range of 0.75-1.25 in. to produce quarter inch
rain rates along the immediate coast. More robust instability over
the Great Basin should yield higher rain rates between 0.5-1
in./hr. in some areas. Upslope enhancement may generate higher
totals in parts of the terrain.

Kebede

Day 3
Valid 12Z Tue Sep 30 2025 - 12Z Wed Oct 01 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE GRAND
STRAND AND SOUTHEAST NORTH CAROLINA...

21z update:
...Southeast...
As noted above in Day 2, the trends for Day 3 QPF are even further
offshore as the sharp eastward turn of T.S. Imelda is expected. The
coastal front and general confluent flow along the Gulf Stream
north and northwest of the developing system will keep some risk of thunderstorm activity in the vicinity of the coastal cites. Much
like Day 2, there was a strong consideration for full removal of
the Slight Risk, however, in coordination with the local forecast
offices felt removal may be premature, with some scattered
thunderstorms in the area with potential for training/back-
building off the Gulf Stream instability gradient and now lies=20
along the urban centers of the Grand Strand through Wilmington, NC.

...Intermountain West...
At the start of the Day 3 period (30.12z), the end of the Hi-Res
CAM window, most show some organized showers and embedded
convective activity along and east of unseasonably strong Pacific
cold front. Initial meridional mid-level trough will be weakening,
but upstream stronger trough will be sharpening the flow and
maintaining favorable divergent flow aloft to provide larger scale
ascent. Highly anomalous moisture with 2.5-4 standard anomaly
values in the .75"+ range remain confluent on 15-25kts of=20
850-700mb southwesterly flow. The remaining Hi-Res CAMs (Nam-Nest=20
and GEM Regional), along with global guidance (GFS/ECMWF) suggest=20
some weak remaining instability/weak lapse rates to support some=20
continued convective activity through the early morning. Some=20
insolation could help recharge the upper reaches of the Snake River
Basin and combined with solid upslope flow may reinvigorate=20
convective activity across the terrain of SE ID into W WY.=20
Scattered spots of 1-2" are possible. This atypical moisture regime
and solid dynamic forcing suggest introduction (supported by=20
continuation from Day 2 period) of a Marginal Risk across the=20
northern Great Basin into the Snake River Basin for Day 3.

Gallina

~~~~Prior Discussion~~~~
...Southeast...
The inherited marginal and slight risk areas along the Southeast
Coast were downsized based on trends in the guidance suggesting
T.C. Nine's hard turn out to sea on Tuesday. Despite the resulting
smaller QPF footprint than previous cycles, the flash flood risk
remains. Instability will be negligible (less than 500 J/Kg
MUCAPE), which supports the possibility that the flood threat will be
due to runoff over saturated soils from Sunday and Monday's
rainfall. Exceedance probabilities of over 2 inches is over 10% in
the 00z ECENS/CMCE, while below 10% in the GEFS along the
immediate Carolina Coast.

Kebede


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!7Gi7bJL_28qHTZbLJ7t8gEZfIhBvOnWS1dGIwrpEhaWf= bh98BRF8eUlsoYd3fODOPIj2o0eXdDbahEmRZQlfksTb7vY$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!7Gi7bJL_28qHTZbLJ7t8gEZfIhBvOnWS1dGIwrpEhaWf= bh98BRF8eUlsoYd3fODOPIj2o0eXdDbahEmRZQlfzQtim78$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!7Gi7bJL_28qHTZbLJ7t8gEZfIhBvOnWS1dGIwrpEhaWf= bh98BRF8eUlsoYd3fODOPIj2o0eXdDbahEmRZQlfpRL4bNk$=20

=3D =3D =3D
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FOUS30 KWBC 290035
QPFERD

Excessive Rainfall Discussion
NWS Weather Prediction Center College Park MD
835 PM EDT Sun Sep 28 2025

Day 1
Valid 01Z Mon Sep 29 2025 - 12Z Mon Sep 29 2025

...THERE IS A MARGINAL RISK OF EXCESSIVE RAINFALL ACROSS PORTIONS=20
OF THE SOUTHWEST AND COASTAL SOUTHEAST...

...Southwest...
We will maintain a Marginal risk area over NM into far west TX=20
with this update. A few more hours of locally intense convection=20
can be expected, with increasing low level easterly flow helping=20
support some continued development through the evening hours. The=20 expectation is that instability will erode overnight resulting in a
decrease in convective coverage and intensity. Generally think the
coverage of any additional flash flood risk has decreased enough=20
to remove the Slight and let the Marginal cover the threat.

...Southeast...
A Marginal risk was maintained from the east coast of FL into
eastern North Carolina. Across FL, onshore flow north of Imelda is
helping enhance coastal convergence and resulting in localized
areas of slow moving convection. This should continue through the
overnight hours, and isolated rainfall totals over 3" are possible.

Farther up the coast we have a stationary front just offshore, with
moisture well north of Imelda interacting with this front. We also
have the mid level trough and upper jet over the Southeast. As the
night progresses we will probably see some of this rain offshore=20
move inland across the Carolinas, with the aforementioned trough=20
and jet helping support this inland advancement. Most of this=20
activity will likely be lower rate rainfall given the low level=20 northeasterly flow and lack of instability. However we may be able=20
to get some higher rates into immediate coastal areas closer to=20
the stationary front. 18z/12z HREF and REFS runs had the higher 3"=20 probabilities along the SC coast, however more recent HRRR and RRFS
runs are shifting towards the NC coast. Recent radar trends also=20
seem to point towards far southeast NC as seeing the best chance of
some slow moving low topped convection getting onshore, which=20
could locally drop upwards of 3" of rainfall. Overall the flash=20
flood threat appears pretty localized along these coastal areas=20
from FL into NC, but the risk is non-zero and a Marginal risk will=20
be maintained.

Chenard

Day 2
Valid 12Z Mon Sep 29 2025 - 12Z Tue Sep 30 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE IMMEDIATE
CAROLINA COASTLINE...

21z update:

...Central New Mexico...
Upper-level trough across the Southwest continues to march east-
northeast, filling fairly rapidly as it reaches the Four Corners in
the early forecast period. This has diminished overall wind field
and pushed the deeper warm conveyor/moisture plume into the Plains.
However, lingering sufficient moisture (.75"-1"), modest
divergence aloft at least initially,clearing for solid insolation
and solid lapse rates (500 J/kg) aloft will allow for potential for
stronger thunderstorms along the Sacramento Range. While the
overall intensity and potential for higher rates is reducing
relative to prior days, there is sufficient rainfall rate/total
signals with 12z HREF probability of 50% of 2"+ and even a small
15% or 3" totals across the Sacramento Range and ridge lines east
of the Rio Grande Valley. As such, will include a small Marginal
Risk area across the ridge of south-central to central New Mexico.

...Southeast...
Strong easterly onshore flow will continue and in proximity to the
coastal front, weak elevated showers and embedded convective
elements are expected along/downstream across the western Piedmont
into the foothills of the southern Appalachian Range, combined with
upslope enhancement localized 1-2" totals are possible and have
expanded the Marginal Risk slightly westward into the eastern
slopes of the Appalachians.

However, the trends for T.S. Imelda remain slow with a sharp
eastward turn, further shifting the QPF gradient southeastward and
offshore relative to prior cycles. However, strong confluent flow
in proximity to the coastal front and Gulf Stream may allow for
scattered thunderstorms to remain possible very close to the
beaches of southeast North Carolina and the South Carolina coast.
Higher probabilities suggest strongest rates/totals will remain
offshore. While there was some solid consideration for removing the
Slight Risk from this update; collaboration with the local
forecast offices and a few remaining solutions that bring the
surface rooted frontal convection further north to the coast have
maintained a narrow Slight Risk mainly for the coastal cities of
Northeast SC/Southeast NC.

...Northern California/Great Basin/Idaho,W Montana Rockies...
The sharp, elongated meridional trough axis has trended a bit
faster in the northern portion to allow for a slightly more evolved
wave along the frontal zone reaching far NW California Coast,
increasing duration of moderate onshore rainfall allowing for a
slight northward expansion of the Marginal Risk across SW OR.
Additionally, the upstream strong shortwave originating from
Kamchatka, rapidly advances and deepens the upstream wave and
further narrows the spacing between it and the leading wave. This
provides increased downstream divergence across the Great Basin
into the Idaho/Montana Rockies, while also strengthening the cross
Sierra Nevada flow to allow for a favorable back-building regime
across western Nevada (just east of the natural rain shadow of the
Sierra Nevada Range). Potential repeating convective elements
across N NV, SE OR and SW ID show an uptick in rainfall totals
with even some HREF probabilities of 1"/hr toward late evening,
early overnight period. Instability is a bit better along the
upwind edge reaching near 1000 J/kg across the Great Basin enough
that 2"/12hr probabilities are nearing 50% in central NV. At this
time, confidence is increasing, but not enough to delineate any
Slight Risk area at this time.

Gallina


~~~~Prior Discussion~~~~

...Southeast...
Guidance continue to depict T.C. Nine propagating north toward the
Southeast Coast on Monday, while a surface front draped along the
coast acts as the focus for heavy rainfall. QPF has trended
downward given slowing trends in the track of T.C. Nine on Monday.
The GFS suite in particular diverges most from the Canadian and
Euro suites when depicting the system's slower forward motion.
Despite this, enough moisture should work its way into the coast
and interact with the surface front to generate scattered thunderstorms. There'll be enough moisture (1.5-2.5in PWATs) and instability
(1000+ J/KG MUCAPE) present to support rainfall rates in excess of
1 in./hr..

...Northern California/Great Basin/Southern Cascades...
An upper low centered over the East Pacific will send mid-level
vortices into the West Coast on Monday. Pacific moisture may
collide with the remnant tropical moisture from Narda to produce
heavy rainfall from northern California into the Great Basin.
Synoptic forcing provided by a strong surface cold front should
focus PWATs in the range of 0.75-1.25 in. to produce quarter inch
rain rates along the immediate coast. More robust instability over
the Great Basin should yield higher rain rates between 0.5-1
in./hr. in some areas. Upslope enhancement may generate higher
totals in parts of the terrain.

Kebede

Day 3
Valid 12Z Tue Sep 30 2025 - 12Z Wed Oct 01 2025

...THERE IS A SLIGHT RISK OF EXCESSIVE RAINFALL FOR THE GRAND
STRAND AND SOUTHEAST NORTH CAROLINA...

21z update:
...Southeast...
As noted above in Day 2, the trends for Day 3 QPF are even further
offshore as the sharp eastward turn of T.S. Imelda is expected. The
coastal front and general confluent flow along the Gulf Stream
north and northwest of the developing system will keep some risk of thunderstorm activity in the vicinity of the coastal cites. Much
like Day 2, there was a strong consideration for full removal of
the Slight Risk, however, in coordination with the local forecast
offices felt removal may be premature, with some scattered
thunderstorms in the area with potential for training/back-
building off the Gulf Stream instability gradient and now lies
along the urban centers of the Grand Strand through Wilmington, NC.

...Intermountain West...
At the start of the Day 3 period (30.12z), the end of the Hi-Res
CAM window, most show some organized showers and embedded
convective activity along and east of unseasonably strong Pacific
cold front. Initial meridional mid-level trough will be weakening,
but upstream stronger trough will be sharpening the flow and
maintaining favorable divergent flow aloft to provide larger scale
ascent. Highly anomalous moisture with 2.5-4 standard anomaly
values in the .75"+ range remain confluent on 15-25kts of
850-700mb southwesterly flow. The remaining Hi-Res CAMs (Nam-Nest
and GEM Regional), along with global guidance (GFS/ECMWF) suggest
some weak remaining instability/weak lapse rates to support some
continued convective activity through the early morning. Some
insolation could help recharge the upper reaches of the Snake River
Basin and combined with solid upslope flow may reinvigorate
convective activity across the terrain of SE ID into W WY.
Scattered spots of 1-2" are possible. This atypical moisture regime
and solid dynamic forcing suggest introduction (supported by
continuation from Day 2 period) of a Marginal Risk across the
northern Great Basin into the Snake River Basin for Day 3.

Gallina

~~~~Prior Discussion~~~~
...Southeast...
The inherited marginal and slight risk areas along the Southeast
Coast were downsized based on trends in the guidance suggesting
T.C. Nine's hard turn out to sea on Tuesday. Despite the resulting
smaller QPF footprint than previous cycles, the flash flood risk
remains. Instability will be negligible (less than 500 J/Kg
MUCAPE), which supports the possibility that the flood threat will be
due to runoff over saturated soils from Sunday and Monday's
rainfall. Exceedance probabilities of over 2 inches is over 10% in
the 00z ECENS/CMCE, while below 10% in the GEFS along the
immediate Carolina Coast.

Kebede


Day 1 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/94epoints.txt__;!!DZ3fjg!9yPOzGL9oyHiBEtiIushDRM9R_t6bGNc0FUruPl0c_5X= vkxXC8CV9jQJNW7EiYKk3oUh7c0Zrl_OVAejQjbu7juiK_0$=20
Day 2 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/98epoints.txt__;!!DZ3fjg!9yPOzGL9oyHiBEtiIushDRM9R_t6bGNc0FUruPl0c_5X= vkxXC8CV9jQJNW7EiYKk3oUh7c0Zrl_OVAejQjbu5RVs0Eo$=20
Day 3 threat area: https://urldefense.com/v3/__https://www.wpc.ncep.noaa.go= v/qpf/99epoints.txt__;!!DZ3fjg!9yPOzGL9oyHiBEtiIushDRM9R_t6bGNc0FUruPl0c_5X= vkxXC8CV9jQJNW7EiYKk3oUh7c0Zrl_OVAejQjbu8X3o1Wg$=20

=3D =3D =3D
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