ACUS01 KWNS 040604
SWODY1
SPC AC 040602

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0102 AM CDT Mon Aug 04 2025

Valid 041200Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
FAR EASTERN WYOMING...SOUTHWEST SOUTH DAKOTA...WESTERN NEBRASKA AND
NORTHEAST COLORADO/KANSAS...

...SUMMARY...
Thunderstorms with severe gusts and hail will be possible today and
tonight from parts of the northern Rockies into the Dakotas and central/southern High Plains.

..Central High Plains...
Rather pronounced shortwave ridging is expected across the central
High Plains through much of the day as troughing intensifies over
the Northwest. With building heights aloft, synoptic forcing for
ascent appears weak. Still, a subtle embedded perturbation should
move eastward across the Rockies late in the afternoon, but it is
unclear how much ascent this feature will support. Given the lack of
stronger forcing for ascent, convective development over the central
High Plains appears tied to diurnal heating and weak low-level
upslope flow along the higher terrain of the Black Hills and eastern
WY. This should favor widely scattered storm development within a
hot and unstable air mass (MLCAPE 2500-3000 J/kg). Northwesterly
flow aloft with elongated hodographs and 45-55 kt of effective shear
will favor high-based supercells initially capable of hail (some
significant) and damaging gusts before moving into more substantial
low-level moisture farther east.

With time, upscale growth appears likely given the strong outflow
expected from the drier low-levels. Most CAM guidance shows one or
more clusters evolving across western/central NE and northeast CO
this evening. Aided by a 40+ kt low-level jet, continued upscale
growth should support these clusters of strong to severe storms into
the overnight hours where damaging winds will be possible.

...Southeast CO into the OK/TX Panhandles...
Strong heating along a lee trough could support isolated
thunderstorm development across the Raton Mesa and TX/OK Panhandles
late this afternoon/evening. Large-scale forcing is not particularly
strong beneath the building upper ridge. Still, model soundings show
uncapped profiles with large buoyancy (3000+ J/kg MLCAPE) and 40-50
kt of effective shear. Should a storm develop it would likely be
supercellular with the potential for hail and damaging gusts. A
brief tornado is also possible as the low-level jet helps expand
hodographs near sunset. The primary uncertainty for higher severe
probabilities remains the limited forcing for ascent and the
uncertainty on higher storm coverage.

...Montana...
Model guidance shows a negatively tilted shortwave trough and
mid-level jet streak moving across portions of the Northwest. This
feature will track northeastward today, spreading broad ascent
across the Northern Rockies. Steep low and mid-level lapse rates
atop modest surface moisture (40s and 50s F dewpoints) will result
in sufficient SBCAPE for scattered thunderstorm development over the
mountains of central ID and western MT by mid-afternoon. Convection
will become more numerous and spread into central and eventually
eastern MT through the evening. Elongated hodographs (30-40 kt of
bulk shear) will support a few organized clusters and rotating
storms capable of damaging winds from strong downdrafts and some
hail. The primary uncertainty for higher severe probabilities is the
potential for limited buoyancy and lack of a stronger signal for
consolidating outflow favoring higher damaging wind potential.

..Lyons.. 08/04/2025

$$

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ACUS01 KWNS 041258
SWODY1
SPC AC 041256

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0756 AM CDT Mon Aug 04 2025

Valid 041300Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE NORTHERN AND CENTRAL HIGH PLAINS...

...SUMMARY...
Thunderstorms with severe gusts and hail will be possible today and
tonight from parts of the northern Rockies into the Dakotas and central/southern High Plains.

...Central High Plains...
Early morning surface analysis shows upper 50s dewpoints in place
across eastern CO, western KS, and western NE, with slightly lower
dewpoints across the NE Panhandle. Moist, southerly low-level flow
will help increase dewpoints across the region throughout the day,
likely resulting in upper 50s to low 60s dewpoints during the
afternoon despite strong heating and boundary-layer mixing. This
should result in a strongly buoyant but minimally capped airmass
across the region by the late afternoon. Additionally, low-level
southeasterly flow will veer to northwesterly in the mid levels,
resulting in moderate to strong deep-layer vertical shear and an
overall wind profile that favors supercells. As such, there is
conditional risk for severe thunderstorms. However, the forcing
mechanism for convective initiation is uncertain.

Upper ridging that currently extends from the Southwest into the
northern High Plains is expected to persist throughout the day, with
heights likely rising across the central High Plains. A shortwave
trough currently moving through the Great Basin is expected to move
within the northern periphery of this ridging, reaching the central
Rockies by this afternoon. Even so, given that heights are forecast
to rise across the central High Plains, the downstream influence of
this wave into the central High Plains will likely be minimal. This
overall lack of larger scale ascent leads to uncertainty regarding
storm coverage since more mesoscale factors, such as low-level
convergence along the lee troughing and weak low-level upslope flow,
will be the mechanisms for convective initiation. High-resolution
guidance offers varied storm coverage, with more recent HRRR runs
(i.e. 06-08Z) keeping the area largely free of storms versus earlier
runs (i.e. 00Z) which show scattered coverage. However, these drier
and less convective HRRR runs appear to be outliers compared to all
the other available guidance, and the general expectation is that
low-level convergence and upslope flow across the Black Hill
vicinity should be enough for scattered convective initiation.

As mentioned previously, the overall environment supports supercells
capable of large to very large hail and strong gusts. Any supercells
that develop could last for a few hours, but should eventually trend
towards a more linear mode with one or more clusters evolving across western/central NE and northeast CO this evening. Aided by a 40+ kt
low-level jet, continued upscale growth should support these
clusters of strong to severe storms into the overnight hours where
damaging winds will be possible.

...Northern Rockies into eastern Montana...
Shortwave trough currently moving through southern OR is forecast to
continue northeastward through the northern Rockies today and
tonight, while becoming increasingly negatively tilted. Ascent
attendant to this wave will interact with a modest buoyant airmass
from central ID into central MT, resulting in scattered to numerous thunderstorms across the region. Initially more cellular storms are
expected across the higher terrain of central ID and western MT with
eventual cold pool amalgamation resulting in one or two
eastward/northeastward progressing clusters across central and
eastern MT. Some hail is possible with the more cellular storms, but
damaging gusts appear to be the greater severe risk. Sufficient
severe storm coverage is anticipated across central and eastern MT
to merit introducing 15% wind probabilities.

...Southern High Plains...
Strong heating along a lee trough could support isolated
thunderstorm development from the Raton Mesa into southeast
CO/northeast NM. The thermodynamic environment here will be similar
to areas farther north, with large buoyancy (3000+ J/kg MLCAPE) and
40-50 kt of effective shear anticipated. A supercell mode is
expected initially with any storms that mature, with large hail,
damaging gusts, and a brief tornado possible. Storm maintenance into
the OK/TX Panhandles is possible, particularly given the
strengthening low-level jet.

...Central/Southeast Texas...
A decaying MCS continues to push southward/southeastward across
central TX at 35 kt. Isolated damaging gusts will remain possible
with this system over the next hour or two, but warming cloud tops
and lowering echo tops suggest this system will continue to weaken.
Additional storm development is possible along the western portion
of the outflow, but low-level stability should mitigate updraft
strength.

..Mosier/Bentley.. 08/04/2025

$$

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ACUS01 KWNS 041637
SWODY1
SPC AC 041636

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1136 AM CDT Mon Aug 04 2025

Valid 041630Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE HIGH PLAINS...

...SUMMARY...
Thunderstorms with severe gusts and large to very large hail will be
possible this afternoon through this evening from parts of the
northern Rockies into the Dakotas and central/southern High Plains.

...Central High Plains...
An upper ridge extending from NM north-northeastward into the
central High Plains will feature a couple of weak disturbances
cresting the ridge through early Tuesday morning. The most notable
disturbance over northeast UT late this morning is forecast to move
east across southern WY by early evening and potentially play a role
in storm development late this afternoon/evening. A seasonably
moist airmass featuring 55-60 deg F dewpoints into eastern WY/NE
Panhandle will undergo strong heating. Low-level southeasterly flow
will veer to northwesterly in the mid levels, resulting in moderate
to strong deep-layer vertical shear and an overall wind profile that
favors supercells. As such, there is conditional risk for severe
thunderstorms. However, the forcing mechanism for convective
initiation is fairly weak. The general expectation is that
low-level convergence and upslope flow across the Black Hills
vicinity should be enough for scattered convective initiation with
other widely scattered storms possible farther south.

The environment supports supercells capable of large to very large
hail and severe gusts. Any supercells that develop could last for a
few hours, but should eventually trend towards a more linear mode
with one or more clusters evolving across western/central NE and
northeast CO this evening. Aided by a 40+ kt low-level jet,
continued upscale growth should support these clusters of strong to
severe storms into the overnight hours where damaging winds will be
possible.

...Northern Rockies into eastern Montana...
Water-vapor imagery shows a potent mid- to upper-level shortwave
trough moving east across OR this morning. This disturbance is
forecast to move into the northern Rockies by early evening and into
the northern High Plains by daybreak. Strong large-scale ascent
associated with this shortwave trough as it acquires a negative
tilt, will favor isolated to scattered storms from the Snake Valley
northward into north-central ID and into western/southwest MT.
Initially cellular storms will pose an isolated risk for severe wind
gusts. As storms move into the high plains, slightly greater
low-level moisture will aid in more numerous storms developing and
their attendant outflow. Scattered severe gusts (60-75 mph) are
possible with this activity as it moves east-northeast across MT.

...Southern High Plains...
Strong heating along a lee trough could support isolated to widely
scattered thunderstorm development from the Raton Mesa into
southeast CO/northeast NM. Ample high-level flow atop strongly
veering low-level winds, coupled with a very unstable airmass on the
western periphery of rich moisture, will favor the possibility for a
few supercells by late afternoon. Large to very large hail, severe
gusts, and a brief tornado are the potential hazards. Some guidance
shows a cluster evolving during the evening with severe gusts
becoming the primary hazard.

...Central/Southeast Texas...
A weakening squall line will continue southward to the middle TX
coast over the next couple of hours with other weak thunderstorm
activity perhaps lingering atop the cold pool. Isolated strong
gusts will probably become increasingly localized during the midday.

..Smith/Wendt.. 08/04/2025

$$

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ACUS01 KWNS 041954
SWODY1
SPC AC 041952

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0252 PM CDT Mon Aug 04 2025

Valid 042000Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE HIGH PLAINS...

...SUMMARY...
Thunderstorms with severe gusts and large to very large hail will be
possible this afternoon through this evening from parts of the
northern Rockies into the Dakotas and central/southern High Plains.

...20z Update...
No changes are needed to the current D1 Convective Outlook. See
previous discussion below for more information.

..Thornton.. 08/04/2025

.PREV DISCUSSION... /ISSUED 1136 AM CDT Mon Aug 04 2025/

...Central High Plains...
An upper ridge extending from NM north-northeastward into the
central High Plains will feature a couple of weak disturbances
cresting the ridge through early Tuesday morning. The most notable
disturbance over northeast UT late this morning is forecast to move
east across southern WY by early evening and potentially play a role
in storm development late this afternoon/evening. A seasonably
moist airmass featuring 55-60 deg F dewpoints into eastern WY/NE
Panhandle will undergo strong heating. Low-level southeasterly flow
will veer to northwesterly in the mid levels, resulting in moderate
to strong deep-layer vertical shear and an overall wind profile that
favors supercells. As such, there is conditional risk for severe
thunderstorms. However, the forcing mechanism for convective
initiation is fairly weak. The general expectation is that
low-level convergence and upslope flow across the Black Hills
vicinity should be enough for scattered convective initiation with
other widely scattered storms possible farther south.

The environment supports supercells capable of large to very large
hail and severe gusts. Any supercells that develop could last for a
few hours, but should eventually trend towards a more linear mode
with one or more clusters evolving across western/central NE and
northeast CO this evening. Aided by a 40+ kt low-level jet,
continued upscale growth should support these clusters of strong to
severe storms into the overnight hours where damaging winds will be
possible.

...Northern Rockies into eastern Montana...
Water-vapor imagery shows a potent mid- to upper-level shortwave
trough moving east across OR this morning. This disturbance is
forecast to move into the northern Rockies by early evening and into
the northern High Plains by daybreak. Strong large-scale ascent
associated with this shortwave trough as it acquires a negative
tilt, will favor isolated to scattered storms from the Snake Valley
northward into north-central ID and into western/southwest MT.
Initially cellular storms will pose an isolated risk for severe wind
gusts. As storms move into the high plains, slightly greater
low-level moisture will aid in more numerous storms developing and
their attendant outflow. Scattered severe gusts (60-75 mph) are
possible with this activity as it moves east-northeast across MT.

...Southern High Plains...
Strong heating along a lee trough could support isolated to widely
scattered thunderstorm development from the Raton Mesa into
southeast CO/northeast NM. Ample high-level flow atop strongly
veering low-level winds, coupled with a very unstable airmass on the
western periphery of rich moisture, will favor the possibility for a
few supercells by late afternoon. Large to very large hail, severe
gusts, and a brief tornado are the potential hazards. Some guidance
shows a cluster evolving during the evening with severe gusts
becoming the primary hazard.

...Central/Southeast Texas...
A weakening squall line will continue southward to the middle TX
coast over the next couple of hours with other weak thunderstorm
activity perhaps lingering atop the cold pool. Isolated strong
gusts will probably become increasingly localized during the midday.

$$

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ACUS01 KWNS 050105
SWODY1
SPC AC 050103

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0803 PM CDT Mon Aug 04 2025

Valid 050100Z - 051200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM
CENTRAL/EASTERN MONTANA INTO THE CENTRAL/SOUTHERN HIGH PLAINS...

...SUMMARY...
Thunderstorms with severe gusts and large to very large hail will be
possible this afternoon through this evening from parts of the
northern Rockies into the Dakotas and central/southern High Plains.

...Northern Rockies vicinity...

An upper shortwave trough, now pivoting across ID will continue to
spread east tonight. An arc of strong to severe storms extending
across central and eastern MT is expected pose a severe wind/hail
risk the next few hours as convection develops north and east across
WW 573. Reference MCD 1887 for short term details. Further west
across ID and portions of western MT, the Marginal risk has been
removed as the main forcing shifts northeast while instability and
shear gradually decrease over the next couple of hours.

...Central/Southern High Plains...

Isolated cells will continue to pose a risk for large to very large
hail and severe/damaging gusts over the next several hours. An
increasing low-level jet this evening will sustain convection, and
may briefly increase the tornado risk this evening. Reference MCD
1888 for more short term details.

..Leitman.. 08/05/2025

$$

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ACUS01 KWNS 050534
SWODY1
SPC AC 050532

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1232 AM CDT Tue Aug 05 2025

Valid 051200Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
NORTH AND SOUTH DAKOTA...

...SUMMARY...
Thunderstorms associated with a threat for severe gusts and large
hail will be possible across parts of the Dakotas today into this
evening.

...Northern Plains...

An upper shortwave trough over the northern Rockies will shift east
across the Dakotas and the Canadian Prairies today/tonight. At the
surface, a cold front will develop east/southeast across MT into the
western Dakotas during the afternoon. Ahead of the front
southeasterly low-level flow will maintain low to mid 60s dewpoints
beneath steep midlevel lapse rates. This will support moderate to
strong destabilization across portions of the western Dakotas and
western NE (MLCAPE 2500+ J/kg), with more modest destabilization
further north and east.

Around 30-40 kt of mid/upper level northwesterly flow atop
vertically veering low-level wind profiles will support supercell
storms initially across western portions of the outlook area. This
will overlap with the corridor of stronger instability and scattered
storms produce large hail and strong/severe gusts will be possible.
Toward evening, a 30-40 kt southerly low-level jet is expected to
develop and upscale development into an MCS is possible across
eastern portions of the outlook area. Forecast guidance varies
regarding the degree of capping that will exist with eastward
extent, but potential for an organized MCS producing strong/severe
gusts appears possible across eastern SD, and may persist
east/southeast toward the Mid-MO Valley during the nighttime hours.

..Leitman/Weinman.. 08/05/2025

$$

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ACUS01 KWNS 051244
SWODY1
SPC AC 051242

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0742 AM CDT Tue Aug 05 2025

Valid 051300Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
NORTH AND SOUTH DAKOTA...

...SUMMARY...
Thunderstorms associated with a threat for severe gusts and large
hail will be possible across parts of the Dakotas today into this
evening.

...Northern Plains...
Warm-air advection showers and thunderstorms are ongoing this
morning across the western Dakotas, where the western edge of the
low-level jet overlaps the eastern edge of the steep mid-level lapse
rates. These storms will likely continue northeastward this morning,
perhaps even expanding in coverage, as the low-level jet persists
and large-scale ascent attendant to an approaching shortwave trough strengthens. Occasionally strong updrafts could produce hail and a
damaging gust or two.

Cloud cover and outflow associated with these storms could result in
an effective warm front extending from a weak low over western SD
eastward across central and eastern SD. The exact location and
sharpness of this front remain uncertain. Given that the shortwave
trough will likely remain well west of the region, low-level
convergence near this boundary as well as the surface low should
both be areas where convective initiation is most likely this
afternoon. Ample buoyancy and vertical shear will be in place for
supercells with the initial development, with large hail and
damaging gusts as the primary risks. Stronger low to mid-level flow
may be in place across eastern SD, contributing to greater low-level
shear and relatively higher tornado potential. Primary concern
across eastern SD is whether or not the warmer low to mid-level
temperatures inhibit the development of mature updrafts.

One other scenario that seems plausible is for storms on southern
periphery the ongoing cluster to become increasingly surface based
as they move eastward/northeastward with time. Given current trends
and recent guidance, this would most likely occur along the eastern
ND/SD border after 20Z. As previously mentioned, hail is possible
within this cluster throughout the day, but the transition to a more surface-based character could introduce the threat for stronger
gusts as well.

A strengthening low-level jet coupled with persistent mid-level
westerlies support the potential for upscale growth in a
east-southeastward progressing MCS. Damaging gusts will be possible
with this MCS, particularly over SD, but increasing low-level
stability should result in a gradually diminishing severe potential
with eastward/southeastward extend into northeast NE, northwest IA,
and southwest MN.

..Mosier/Bentley.. 08/05/2025

$$

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ACUS01 KWNS 051629
SWODY1
SPC AC 051628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Tue Aug 05 2025

Valid 051630Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE DAKOTAS...

...SUMMARY...
Scattered severe thunderstorms with an accompanying risk for large
hail, severe wind gusts, and perhaps a couple of tornadoes will be
possible this afternoon through much of the evening across the
Dakotas.

...Northern Plains...
Visible-satellite/radar mosaic imagery late this morning shows a
cluster of sub-severe thunderstorms associated with a lead lobe of
mid-level ascent/MCV moving through the base of a larger-scale
trough centered over MT/Saskatchewan. Deleterious effects of
widespread cloud cover over far northern SD into ND will likely
hinder appreciable destabilization through the early afternoon.
However, earlier forecast thinking of a differential heating zone
becoming more focused along the ND-SD border to the east of a weak
cyclone will potentially become consequential for the severe risk
later this afternoon/evening.

A reservoir of adequately rich low-level moisture with dewpoints in
the mid-upper 60s deg F will likely protrude northward into southern
ND as the airmass destabilizes this afternoon. Cloud breaks will
contribute to moderate to strong buoyancy (1500-3500 J/kg MLCAPE) to
the south of more stable conditions likely being maintained
throughout the day near the Canadian border. Forecast soundings
show enlarged low-level hodographs by mid-late afternoon and into
the evening with a 40-kt southerly LLJ centered on SD.

Short-term model guidance indicates renewed storm development is
most likely east of the low along the differential heating zone with
this activity spreading east into more vorticity-rich air.
Seasonably large uncertainty remains regarding this forecast during
the 22-02z period in which peak severe may occur. Supercells
capable of all hazards will be possible before clusters evolve and
the propensity for cold pool coalescence becomes detrimental for the
supercell threat and wind becomes the primary hazard later this
evening. Considerable uncertainty exists overnight on the potential
evolution of a cluster and an incipient wind threat into parts of
the MO Valley and Upper Midwest.

..Smith/Wendt.. 08/05/2025

$$

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ACUS01 KWNS 051955
SWODY1
SPC AC 051954

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0254 PM CDT Tue Aug 05 2025

Valid 052000Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE DAKOTAS...

...SUMMARY...
Scattered severe thunderstorms with an accompanying risk for large
hail, severe wind gusts, and perhaps a couple of tornadoes will be
possible this afternoon through much of the evening across the
Dakotas.

...20z Update...
No changes were made to the D1 Convective Outlook.

Air mass recovery trends continue to be monitored across the Dakotas
in the wake of morning convection. Breaks in the cloud cover have
led to heating across central/western South Dakota to the southern
North Dakota line. Warm moist air continues to spread northward
south of the differential heating boundary located across southern
ND into central SD. It appears that redevelopment/re-intensification
of thunderstorm activity is likely through the afternoon as further destabilization continues. See MCD#1890 for more detailed
information on expected storm evolution through the afternoon.

..Thornton.. 08/05/2025

.PREV DISCUSSION... /ISSUED 1128 AM CDT Tue Aug 05 2025/

...Northern Plains...
Visible-satellite/radar mosaic imagery late this morning shows a
cluster of sub-severe thunderstorms associated with a lead lobe of
mid-level ascent/MCV moving through the base of a larger-scale
trough centered over MT/Saskatchewan. Deleterious effects of
widespread cloud cover over far northern SD into ND will likely
hinder appreciable destabilization through the early afternoon.
However, earlier forecast thinking of a differential heating zone
becoming more focused along the ND-SD border to the east of a weak
cyclone will potentially become consequential for the severe risk
later this afternoon/evening.

A reservoir of adequately rich low-level moisture with dewpoints in
the mid-upper 60s deg F will likely protrude northward into southern
ND as the airmass destabilizes this afternoon. Cloud breaks will
contribute to moderate to strong buoyancy (1500-3500 J/kg MLCAPE) to
the south of more stable conditions likely being maintained
throughout the day near the Canadian border. Forecast soundings
show enlarged low-level hodographs by mid-late afternoon and into
the evening with a 40-kt southerly LLJ centered on SD.

Short-term model guidance indicates renewed storm development is
most likely east of the low along the differential heating zone with
this activity spreading east into more vorticity-rich air.
Seasonably large uncertainty remains regarding this forecast during
the 22-02z period in which peak severe may occur. Supercells
capable of all hazards will be possible before clusters evolve and
the propensity for cold pool coalescence becomes detrimental for the
supercell threat and wind becomes the primary hazard later this
evening. Considerable uncertainty exists overnight on the potential
evolution of a cluster and an incipient wind threat into parts of
the MO Valley and Upper Midwest.

$$

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ACUS01 KWNS 060047
SWODY1
SPC AC 060045

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0745 PM CDT Tue Aug 05 2025

Valid 060100Z - 061200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTH DAKOTA AND FAR SOUTHEAST NORTH DAKOTA...

...SUMMARY...
Strong to severe thunderstorms with an accompanying risk for large
hail and severe wind gusts will persist the remainder of the
evening/early overnight.

...Northern Plains Vicinity...

Strong to severe storms may persist/develop over the next several
hours, mainly across parts of SD ahead of a surface low and cold
front. Some marginally severe storms have occurred, with hail from
around nickel to half dollar size noted in local storm reports the
past few hours. Wind gusts from 45-60 mph have also occurred.
Overall, convection outside of the ongoing cluster across southeast
ND has not been very robust. Looking at the 00z RAOB from ABR, 0-3km
lapse rate are lackluster (around 5.7 C/km), limiting vertical
accelerations in the low-levels. Nevertheless, steep midlevel lapse
rates are indicated (around 7.5 C/km 700-500 mb) amid 2000+ MLCAPE
across SD, decreasing with north and east extent. Vertical shear
also remains favorable for storm organization, if more robust
convection can evolve behind the ND cluster.

Evening CAMs guidance still suggests an MCS may develop across parts
of SD downstream into the Mid-MO Valley vicinity overnight. However,
stronger capping is evident into NE/IA. Given uncertainty amid an at
least modestly favorable environment, severe probabilities have only
been trimmed mainly across the western and northern outlook area
(WY/MT into ND) where confidence is greatest potential has lessened.
Severe probabilities across SD and vicinity will be maintained.

..Leitman.. 08/06/2025

$$

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ACUS01 KWNS 060515
SWODY1
SPC AC 060513

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1213 AM CDT Wed Aug 06 2025

Valid 061200Z - 071200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN/CENTRAL PLAINS TO THE MID-MISSISSIPPI VALLEY...AND PART
OF NORTHERN MINNESOTA...

...SUMMARY...
Isolated strong to severe thunderstorms are possible across parts of
the northern/central Plains to the Mid-Mississippi Valley, and over
part of northern Minnesota today and tonight.

...Northern/Central Plains to IA/MO and northern MN...

Low-amplitude upper ridging will persist across the region today.
Moderate upper level west/northwesterly flow around 40 kt at 500 mb
will spread across the northern Rockies to the Upper Midwest
vicinity amid nebulous large-scale ascent. At the surface, a
seasonally moist airmass is in place, with generally 60-70 F
dewpoints present beneath a plume of steep midlevel lapse rates
(weaker further north). This will support a corridor of moderate to
strong instability across SD/NE into parts of MN/IA and vicinity.

A decaying MCS may be located over IA or the Lower MO Valley at 12z.
Some locally strong wind gusts could occur with this activity before
weakening during the morning. Some guidance redevelops convection
across the Lower-MO/Mid-MS Valley during the afternoon/evening
across this area, possibly aided by any remnant MCV or outflow. This
activity would conditionally pose a damaging wind risk.

Additional convection may develop near the Black Hills into western
NE along surface boundary/residual outflow and within southeasterly
low-level upslope flow within a very moist/unstable airmass. Without
any stronger forcing mechanism, coverage may be low and confidence
is low. However, any storm developing within this strongly unstable
airmass will encounter supercell wind profiles. A conditional risk
for large hail and damaging winds will exist, but given uncertainty,
will maintain Marginal risk (level 1 of 5).

Further north across northern MN, a few storms may develop along the
southern periphery of the Canadian Prairies shortwave upper trough
and surface low. Lapse rates will be weaker across this area and the
favorable thermodynamic environment will be narrow. Any stronger
storms will likely remain close to the international border, but
could produce locally strong gusts or marginal hail.

..Leitman/Weinman.. 08/06/2025

$$

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ACUS01 KWNS 061240
SWODY1
SPC AC 061238

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Wed Aug 06 2025

Valid 061300Z - 071200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN/CENTRAL PLAINS TO THE MID-MISSISSIPPI VALLEY. AND PART
OF NORTHERN MINNESOTA...

...SUMMARY...
Isolated strong to severe thunderstorms are possible across parts of
the northern/central Plains to the Mid-Mississippi Valley, and over
part of northern Minnesota today and tonight.

...Northern/Central Plains into the Mid MS Valley...
An MCS continues to push southward across the Mid MO Valley this
morning. The current motion, particularly the westward backbuilding
of storms into more of east-central NE, have oriented this system
favorably to a moist low-level jet, which should support maintenance
of this line for the next few hours. Echo tops within this system
remain fairly cool and occasionally strong updrafts have persisted
for the last several hours. Additionally, a notable rise/fall
pressure couplet exists with this system, as sampled by the +4 mb
pressure rise as SUX. These factors indicate the MCS remains mature
and could still occasionally produce damaging gusts over the next
few hours across southeast NE, southwest IA, northwest MO, and far
northeast KS. This MCS should begin to weaken later this morning
when the low-level jet weakens.

The region will be within the mostly zonal flow between the upper
ridging centered over NM and a shortwave trough moving through SK
and MB. Some rising heights are possible during the second half of
the period as the pattern amplifies ahead of a shortwave trough
moving into the northern Rockies. A belt of stronger mid-level flow
(i.e. around 40 kt at 500 mb) will extend across the region, and
diurnal heating of the moist airmass in place will foster moderate
to strong buoyancy. The resulting combination of buoyancy and shear
would favor strong to severe thunderstorms, but the satellite
imagery lacks any notable disturbances upstream and the large-scale
ascent is nebulous. The surface pattern also lacks any well-defined
features, with only weak troughing sampled from the central Dakotas
to a weak low over northeast CO.

As such, when and where convective initiation occurs, if it occurs
at all, is uncertain. Convective initiation appears most likely near
the Black Hills into western NE within southeasterly low-level
upslope flow within a very moist/unstable airmass. Environmental
conditions support supercells with a conditional risk for large hail
and damaging winds. However, given the uncertainty regarding
coverage, will maintain Marginal risk (level 1 of 5).

...Northern MN...
A few storms may develop along the southern periphery of the
Canadian Prairies shortwave upper trough and surface low. Lapse
rates will be weaker across this area and the favorable
thermodynamic environment will be narrow. Any stronger storms will
likely remain close to the international border, but could produce
locally strong gusts or marginal hail.

..Mosier/Bentley.. 08/06/2025

$$

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ACUS01 KWNS 061630
SWODY1
SPC AC 061629

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Wed Aug 06 2025

Valid 061630Z - 071200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN/CENTRAL PLAINS TO THE MID-MISSISSIPPI VALLEY. AND PART
OF NORTHERN MINNESOTA...

...SUMMARY...
Isolated strong to severe thunderstorms are possible across parts of
the northern/central Plains to the Mid-Mississippi Valley, and over
part of northern Minnesota this afternoon and tonight.

...Northern/Central Plains into the Mid MS Valley...
Water-vapor imagery late this morning shows a quasi-zonal flow
regime from the northern Intermountain region east into the central
Great Plains. A disturbance along the ND/Canadian border will
continue east into the western ON vicinity late tonight. Weak
mid-level height rises are forecast over the northern Great Plains
downstream of a trough moving east into the northwestern CONUS from
the eastern Pacific. A belt of stronger mid-level flow (i.e. around
40 kt at 500 mb) will extend across the region, and diurnal heating
of the moist airmass in place will foster moderate to strong
buoyancy.

Forecast soundings show a vigorous combination of shear/buoyancy but
nebulous forcing mechanisms suggest storm coverage later
today/tonight will likely remain isolated/sparse. Little in the way
of large-scale forcing for ascent will contribute to suppressing
convective development through at least mid afternoon. Considerable uncertainty in storm development is apparent in convection-allowing
models and some of these models show isolated storms perhaps
favoring the greater Black Hills area. Will maintain a Marginal
risk (level 1 of 5) despite favorable environmental conditions for
supercells. Later tonight in association with low-level warm-air
advection, a cluster or two of storms may evolve from the eastern
half of SD/NE into the lower MO Valley/mid MS Valley. An isolated
hail/wind threat could accompany this activity.

...Northern MN...
A few storms may develop along the southern periphery of the
Canadian Prairies shortwave upper trough and surface low. Lapse
rates will be weaker across this area and the favorable
thermodynamic environment will be narrow. Any stronger storms will
likely remain close to the international border, but could produce
locally strong gusts or marginal hail.

..Smith/Wendt.. 08/06/2025

$$

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ACUS01 KWNS 062000
SWODY1
SPC AC 061958

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Wed Aug 06 2025

Valid 062000Z - 071200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS PARTS OF THE CENTRAL/NORTHERN PLAINS TO THE UPPER MISSISSIPPI VALLEY AND
MINNESOTA...

...SUMMARY...
Isolated strong to severe thunderstorms are possible across parts of
the northern/central Plains to the Mid-Mississippi Valley, and over
part of northern Minnesota this afternoon and tonight.

...20z Update...
The prior forecast remains largely on track with minimal changes.
Current observations show stout capping in place over much of the
central Plains. However, robust surface heating of a seasonably
moist air mass (surface dewpoints upper 60s to low 70s F) is ongoing
across parts of South Dakota and northern Nebraska. With continued
heating this afternoon, gradual destabilization is expected to
continue. Initial high-based convection should develop late this
afternoon across eastern WY and western SD, and will gradually move
eastward into moderate to large buoyancy. With 40 kt of mid-level
flow also in place, there exists the potential for isolated
supercells with hail and damaging gusts as the primary threats. The
main uncertainty for higher severe probabilities today remains the
nebulous forcing for ascent which should continue to favor
sparse/isolated storm coverage into early evening.

...Eastern Plains and Missouri Valley to Midwest...
Afternoon model guidance continues to show an increase in convection
tonight associated with low-level warm air advection from the
expected 30-40 kt low-level jet. The highest confidence in scattered
storms is from the eastern half of SD/NE into parts of IA and
southern MN late tonight. With steep mid-level lapse rates above a predominately stable boundary layer, hail and isolated damaging gust
are possible. The MRGL risk was adjusted over southern NE to better
match recent model guidance for higher storm coverage.

Otherwise, the outlook remains unchanged. See the prior discussion
for the previous discussion.

..Lyons.. 08/06/2025

.PREV DISCUSSION... /ISSUED 1129 AM CDT Wed Aug 06 2025/

...Northern/Central Plains into the Mid MS Valley...
Water-vapor imagery late this morning shows a quasi-zonal flow
regime from the northern Intermountain region east into the central
Great Plains. A disturbance along the ND/Canadian border will
continue east into the western ON vicinity late tonight. Weak
mid-level height rises are forecast over the northern Great Plains
downstream of a trough moving east into the northwestern CONUS from
the eastern Pacific. A belt of stronger mid-level flow (i.e. around
40 kt at 500 mb) will extend across the region, and diurnal heating
of the moist airmass in place will foster moderate to strong
buoyancy.

Forecast soundings show a vigorous combination of shear/buoyancy but
nebulous forcing mechanisms suggest storm coverage later
today/tonight will likely remain isolated/sparse. Little in the way
of large-scale forcing for ascent will contribute to suppressing
convective development through at least mid afternoon. Considerable uncertainty in storm development is apparent in convection-allowing
models and some of these models show isolated storms perhaps
favoring the greater Black Hills area. Will maintain a Marginal
risk (level 1 of 5) despite favorable environmental conditions for
supercells. Later tonight in association with low-level warm-air
advection, a cluster or two of storms may evolve from the eastern
half of SD/NE into the lower MO Valley/mid MS Valley. An isolated
hail/wind threat could accompany this activity.

...Northern MN...
A few storms may develop along the southern periphery of the
Canadian Prairies shortwave upper trough and surface low. Lapse
rates will be weaker across this area and the favorable
thermodynamic environment will be narrow. Any stronger storms will
likely remain close to the international border, but could produce
locally strong gusts or marginal hail.

$$

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ACUS01 KWNS 070101
SWODY1
SPC AC 070059

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Wed Aug 06 2025

Valid 070100Z - 071200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE NORTHERN/CENTRAL PLAINS AND MIDWEST...AND ALSO FOR NORTHWEST MN...

...SUMMARY...
Isolated strong to severe thunderstorms are possible across parts of
the northern/central Plains to the Mid-Mississippi Valley, and over
part of northern Minnesota, this evening into late tonight.

...Eastern WY/southeast MT into western/central SD/northwest NE...
A favorable conditional environment remains in place this evening
from eastern WY/far southeast MT into western SD/northwest NE, with
moderate to strong buoyancy and effective shear of 40-50 kt.
However, large-scale ascent is generally weak, and storms that
developed across far eastern WY have been very isolated and
relatively slow to intensify. A severe storm or two remains possible
through the evening, with a threat of isolated hail and localized
strong to severe gusts. Isolated strong to severe storm development
also cannot be ruled out this evening across central SD, in the
vicinity of diffuse surface boundary.

...Northern MN...
Strong storms have developed this evening across southeast MB, in
the vicinity of a surface trough. Stronger large-scale ascent and
greater storm coverage are expected to remain north of the
international border, but development of an isolated strong storm or
two cannot be ruled out through dusk across northwest MN, within a
moderately buoyant environment.

...Eastern NE/SD into IA/northern MO/northeast KS late tonight...
Elevated convection may develop late tonight from eastern NE/western
IA into northeast KS/northwest MO, within a low-level warm advection
regime. Moderate to strong elevated buoyancy, steep midlevel lapse
rates, and modestly favorable effective shear could support at least
transient storm organization. One or two southeastward-moving
clusters may develop overnight within this regime, with a threat of
isolated hail and strong to locally damaging gusts.

...Central/eastern MT into western ND late tonight...
Elevated convection may increase overnight from central into
northeast MT, in advance of a mid/upper-level shortwave trough
moving across the interior Northwest. Moisture and elevated buoyancy
will initially be modest, though small hail and gusty winds could
accompany these storms overnight. There is some potential for this
convection to intercept greater moisture/instability across
northeast MT very late in the period, though at this time it appears
that organized-severe potential may remain limited until near/after
12Z.

..Dean.. 08/07/2025

$$

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ACUS01 KWNS 070601
SWODY1
SPC AC 070559

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Thu Aug 07 2025

Valid 071200Z - 081200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR PARTS OF
NORTH DAKOTA...

...SUMMARY...
Scattered severe thunderstorms are expected later today into
tonight. The most likely corridor is centered on North Dakota, where
a few tornadoes, very large hail, and significant severe gusts are
possible.

...Northern Great Plains...
Significant severe storms capable of producing wind gusts of 75+
mph, very large hail, and possibly a few tornadoes are still
expected in an area centered on ND later today into tonight.

A mid/upper-level trough is forecast to amplify over parts of the Northwest/northern Rockies today as it moves eastward. One or more low-amplitude vorticity maxima may precede the larger-scale trough
and move across the northern Great Plains during the afternoon and
evening. A surface low is forecast to gradually deepen across the
northern High Plains. Rich low-level moisture beneath steep midlevel
lapse rates will result in strong to extreme buoyancy within the
warm sector of this cyclone, and also near/north of a baroclinic
zone that will extend east/northeast of the low. This instability
combined with moderate deep-layer shear will result in a very
favorable conditional environment for severe storms.

Guidance generally depicts one or more intense storm clusters moving
across ND sometime later today into tonight, but considerable spread
remains regarding timing of the primary threat, and the duration and
coverage of supercells. There is some potential for morning elevated
convection to become increasingly organized with time, with renewed
development during the afternoon possible near the surface low and
baroclinic zone.

Any supercells within this regime would pose a threat of very large
hail, along with some tornado potential, especially near the
baroclinic zone. A tendency toward clustering and MCS development is
expected with time, increasing the threat for one or more swaths of
significant severe wind, along with some potential for line-embedded
tornadoes. The southern and eastern extent of higher-end severe
potential remains uncertain, due to differences regarding storm
timing and the position of the main baroclinic zone.

Farther west, isolated to widely scattered supercells may develop
within a moderately unstable post-frontal regime from central into
eastern MT. Elongated hodographs and steep lapse rates will support
severe hail and wind potential with these cells. Some clustering
remains possible within this regime as well, and depending on the
evolution of downstream convection, storms that initiate in MT may
eventually spread into western/central ND late tonight with a
continued severe threat.

...IL/eastern IA into WI and western upper MI...
Some potential for strong to locally severe storms remains evident
within a broad area from IL/eastern IA into WI and western upper MI,
though uncertainty remains regarding the potential for a more
organized threat somewhere within this broader area.

Guidance varies regarding the evolution of morning convection across
parts of IA/MO, and whether a well-defined MCV will emerge from this
area. However, even a weak MCV or other low-amplitude vorticity
maxima may aid in scattered to widespread storm development late
this afternoon into the evening, within a modest low-level warm
advection regime. Deep-layer flow will be relatively modest, but
rich moisture and moderate to strong buoyancy will support a threat
for at least isolated hail and damaging wind.

..Dean/Weinman.. 08/07/2025

$$

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ACUS01 KWNS 071251
SWODY1
SPC AC 071250

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 AM CDT Thu Aug 07 2025

Valid 071300Z - 081200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS MUCH OF
NORTH DAKOTA...

...SUMMARY...
Scattered severe thunderstorms are expected later today into tonight
across the northern Plains. The most likely corridor is centered on
North Dakota, where a few tornadoes, very large hail, and
significant severe gusts are possible.

...Northern Plains...
Elevated thunderstorms are ongoing across northeastern MT this
morning, supported by warm-air advection throughout the northwestern
periphery of surface low over southeast MT. Steep mid-level lapse
rates remain in place downstream of these storms, and southwesterly
mid-level flow will persist, so the general expectation is for these
storms to continue through the morning into the early afternoon.
Cloud cover associated with these storms could result in a
differential heating zone that with create a warm-front-like feature
across northern ND. At the same time, moisture low-level
southeasterly flow will continue across the northern Plains, with
dewpoints likely in the upper 60s/low 70s across much of the region
by the early afternoon.

The surface low over southeast MT is forecast to drift eastward this
morning towards the MT/WY/SD border intersection vicinity. To the
north of this low, the combination of low-level moisture convergence
and strengthening large-scale ascent will likely result in
convective initiation by the early afternoon. Surface dewpoints in
the upper 60s/low 70s and surface temperatures in the 80s beneath
steep mid-level lapse rates will result in an impressive
thermodynamic environment from the MT/ND border downstream into more
of ND. Most guidance suggests MLCAPE from 3000 to 4000 J/kg.
Moderate shear is also expected within this initiation zone,
supporting an initially supercellular storm mode. All severe hazards
would be possible with these supercells, including very large hail
exceeding 2" in diameter, significant severe gusts around 75 mph,
and tornadoes. Clustering and upscale growth appears probable, with
the resulting MCS then tracking eastward across ND.

Given the extreme buoyancy and moderate westerly flow aloft, there
is some potential for the development of a robust rear inflow jet
and resulting MCS that could be qualified as a derecho. However,
confidence in the development of derecho is too low to increase wind probabilities with this outlook. Regardless, significant wind gusts
appear possible, particularly if the previously mentioned
warm-front-like feature develops and acts as a favored corridor for
MCS propagation. Low-level southeasterly flow is also expected to be
strong enough for some potential for line-embedded tornadoes.

Additional elevated thunderstorms are possible in the wake of this
MCS amid modest warm-air advection atop the MCS outflow. Some large
hail is possible within these storms.

...Northern High Plains...
Farther west, isolated to widely scattered supercells may develop
within a moderately unstable post-frontal regime from central into
eastern MT. Elongated hodographs and steep lapse rates will support
severe hail and wind potential with these cells. Some clustering
remains possible within this regime as well, and depending on the
evolution of downstream convection, storms that initiate in MT may
eventually spread into western/central ND late tonight with a
continued severe threat.

...Northern MO/IA into the Upper Midwest...
Elevated thunderstorms are currently ongoing across southern IA and
northern MO, supported by warm-air advection resulting from a
low-level jet that extends from the TX Panhandle through eastern KS.
Steep mid-level lapse rates are present across much of the region
(sampled by the 12Z TOP sounding), and these storms will likely
continue through the afternoon. An isolated strong wind gusts is
possible with these storms.

Additional thunderstorms are possible later this evening farther
northeast in central/southern WI and northern IL as the low-level
jet strengthens again. Deep-layer flow will be relatively modest,
but rich moisture and moderate to strong buoyancy will support a
threat for at least isolated hail and damaging wind.

..Mosier/Bentley.. 08/07/2025

$$

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ACUS01 KWNS 071615
SWODY1
SPC AC 071614

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1114 AM CDT Thu Aug 07 2025

Valid 071630Z - 081200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
INTO TONIGHT ACROSS MUCH OF NORTH DAKOTA...

...SUMMARY...
Scattered severe thunderstorms are expected later today into tonight
across the northern Plains. The most likely corridor is centered on
North Dakota, where a few tornadoes, very large hail, and
significant severe gusts are possible.

...Eastern MT/Dakotas/Western MN...
A large upper trough is digging into the Pacific Northwest region
today, with several shortwave perturbations tracking from the
northern Great Basin into MT/ND. One feature is currently over
eastern MT and has been fostering scattered thunderstorms across
that region. Convection in this area is currently in a diurnal
lull, but may re-invigorate later this afternoon across parts of
central ND as daytime heating/destabilization occurs. Backed
low-level winds, dewpoints in the 70s, and high CAPE values will
promote a favorable environment for a few supercells capable of very
large hail, a few tornadoes, and damaging wind gusts. These storms
could persist into the evening, tracking into western MN.

Another shortwave trough currently over western ID will overspread
the mountains of ID/western MT this afternoon, promoting the
development of scattered strong storms. This activity should
intensify further as it moves into a very moist/unstable airmass
across southeast MT, with a consensus of CAM guidance suggesting
upscale growth into a bowing complex by early evening. As these
storms progress rapidly eastward across ND/northern SD, there
remains the potential for a swath of significant wind damage, along
with large hail and a tornado or two. Some guidance suggests the
MCS will remain severe well into the night, affecting parts of
western/central MN.

..Hart/Wendt.. 08/07/2025

$$

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ACUS01 KWNS 072000
SWODY1
SPC AC 071959

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Thu Aug 07 2025

Valid 072000Z - 081200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS
OF THE NORTHERN PLAINS....

...SUMMARY...
Scattered severe thunderstorms are expected later today into tonight
across the northern Plains. The most likely corridor is centered on
North Dakota, where a few tornadoes, very large hail, and a
conditional risk for significant severe gusts are possible.

...20z Update Northern Plains...
Early afternoon surface and satellite observations show low-level
convergence increasing along the intersection of an outflow
boundary/composite front and weak lee low over eastern MT. Along and
south of the front, strong diurnal heating should gradually
destabilize a very moist air mass with dewpoints in the low 70s F.
Large to extreme CAPE is expected, owing to steep mid-level lapse
rates, though with some capping likely to remain in place with
southward extent. Rapid thunderstorm initiation appears probable
this afternoon along the low-level convergence zone and in the
higher terrain farther west as a shortwave trough proceeding the
primary mid-level wave over the Northern Rockies ejects eastward.
Initial storm mode is likely to be supercellular along or on the
immediate cool side of the surface boundary. This would initially
favor a large hail risk (some significant), and the potential for a
few tornadoes, should storms become surface based.

Tonight, the primary uncertainty continues to be small-scale storm
dynamics governing upscale growth and the potential for bowing
MCS/rear-inflow jet development. Should this occur relatively early
on in the convective evolution (as shown by some CAMs), significant
damaging winds (Gusts 80+ mph) are possible across portions of ND/SD
through tonight. However, this remains highly uncertain and
conditional. Regardless of the initial evolution, significant ascent
from the primary upper trough ejecting eastward appears robust
enough to support upscale growth with any ongoing convection and
additional storms emanating from eastern MT later tonight. This
could result in one or more clusters of strong storms capable of
damaging gusts, hail and a tornado or two. Given recent trends, have
shifted the northern bound of the level 3 Enhanced northward and
eastward across ND/MN for significant damaging wind potential.
Otherwise, see MCD #1896 and #1897 for short-term information.

..Lyons.. 08/07/2025

.PREV DISCUSSION... /ISSUED 1114 AM CDT Thu Aug 07 2025/

...Eastern MT/Dakotas/Western MN...
A large upper trough is digging into the Pacific Northwest region
today, with several shortwave perturbations tracking from the
northern Great Basin into MT/ND. One feature is currently over
eastern MT and has been fostering scattered thunderstorms across
that region. Convection in this area is currently in a diurnal
lull, but may re-invigorate later this afternoon across parts of
central ND as daytime heating/destabilization occurs. Backed
low-level winds, dewpoints in the 70s, and high CAPE values will
promote a favorable environment for a few supercells capable of very
large hail, a few tornadoes, and damaging wind gusts. These storms
could persist into the evening, tracking into western MN.

Another shortwave trough currently over western ID will overspread
the mountains of ID/western MT this afternoon, promoting the
development of scattered strong storms. This activity should
intensify further as it moves into a very moist/unstable airmass
across southeast MT, with a consensus of CAM guidance suggesting
upscale growth into a bowing complex by early evening. As these
storms progress rapidly eastward across ND/northern SD, there
remains the potential for a swath of significant wind damage, along
with large hail and a tornado or two. Some guidance suggests the
MCS will remain severe well into the night, affecting parts of
western/central MN.

$$

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ACUS01 KWNS 080101
SWODY1
SPC AC 080059

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Thu Aug 07 2025

Valid 080100Z - 081200Z

...THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FOR ND AND
ADJACENT PARTS OF EASTERN MT AND NORTHWEST MN...

...SUMMARY...
Severe thunderstorms are expected tonight across the northern
Plains, in an area centered on North Dakota. One or more swaths of
significant severe winds are possible, along with potential for
large to very large hail and a few tornadoes.

...Northern Plains vicinity...
Multiple storm clusters are ongoing this evening from south-central
and eastern MT into northwest ND, with more isolated discrete
development near a weak surface boundary across far northeast ND.
The environment downstream of the MT storm clusters remains rather
volatile, with rich low-level moisture, steep midlevel lapse rates,
MLCAPE of 2000-4000 J/kg, and effective shear of 40-50 kt. As the
ongoing storm clusters and attendant outflow move into this volatile environment through the evening, upscale growth into an intense MCS
will be possible, potentially resulting in a swath of significant
severe gusts moving across ND later this evening into the overnight
hours. A couple supercells also remain possible, with a threat of
very large hail. Backed surface winds and modestly enhanced
low-level shear/SRH could also support some tornado potential, both
with any sustained supercells, and embedded within any intense MCS
that develops later tonight. See MCDs 1899 and 1900 for more
information regarding the short-term threat in this area.

While confidence remains high in an increasing severe threat this
evening across ND, some uncertainty remains regarding the evolution
of ongoing storms, and the favored corridor for significant-severe
potential later tonight. Longevity and eastward extent of the threat
overnight also remain somewhat uncertain, but some severe potential
may reach parts of west-central/northwest MN by the end of the
period.

...Central High Plains...
Isolated strong to severe storms may continue through dusk from near
the NE/SD border southward into northwest KS, within a strongly
unstable and favorably sheared environment. Rather stout downstream
MLCINH (which will continue to increase with time) is expected to
limit the longevity of these storms, but some threat for hail and
strong to severe gusts will continue for as long as these storms
persist.

..Dean.. 08/08/2025

$$

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ACUS01 KWNS 080601
SWODY1
SPC AC 080600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Fri Aug 08 2025

Valid 081200Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR THE EASTERN
DAKOTAS INTO MUCH OF MN AND NORTHWEST WI...

...SUMMARY...
Scattered severe thunderstorms are possible later today and tonight
across parts of the Upper Midwest. Scattered damaging winds, large
hail, and couple tornadoes are possible.

...Synopsis...
A seasonably deep upper-level trough will move eastward into the
northern Great Plains later today into tonight. In conjunction with
this trough, a cold front will move across parts of the
northern/central Plains into parts of MN/IA. The stronger
mid/upper-level flow associated with the trough will generally lag
the cold front, though there is some potential for increasing
deep-layer flow/shear to impinge on a strongly unstable environment
during the afternoon and evening.

...Dakotas into MN and northern WI...
Elevated convection and possibly a remnant MCS will likely be
ongoing at the start of the period somewhere from the eastern
Dakotas into northern MN. These storms could pose a threat of
isolated damaging wind and hail.

The influence of the early-day convection results in considerable
uncertainty regarding storm evolution later in the day. Convection
may persist through much of the day behind the front, and also
potentially along/north of an outflow boundary that will likely be
in place somewhere across northern MN. Warm-sector development along
the cold front will be possible by late afternoon, though stronger
large-scale ascent attendant to the approaching trough will not
overspread the region until evening, when widespread storm
development will become possible.

Steep lapse rates atop rich low-level moisture will support strong
to extreme buoyancy along/ahead of the cold front, and to the warm
side of any outflows. Deep-layer shear will become sufficient for
supercells, though deep-layer shear generally parallel to the cold
front could result in a quick transition to cluster or linear mode.
Any sustained warm-sector supercells could pose a threat of large
hail and a tornado. Damaging winds may become the primary threat as
storms increase and spread eastward through the evening into late
tonight.

Greater severe probabilities may eventually be needed for part of
the region, if uncertainties regarding the influence of early-day
convection and potentially late timing of redevelopment are
resolved.

...Black Hills into northeast CO and the NE Panhandle...
Guidance varies regarding the potential for post-frontal storm
development from the Black Hills into northeast CO and the NE
Panhandle. Steep lapse rates and moderate deep-layer shear would
conditionally support supercells within this regime, with a threat
of hail and strong to severe gusts. However, some guidance is rather
aggressive with drying behind the front, resulting in limited storm
coverage. This area will be monitored for greater hail
probabilities, if trends support development of multiple sustained
cells.

...Southern High Plains...
High-based convection is expected to develop this afternoon within a
hot and well-mixed environment across the southern High Plains.
Deep-layer flow will generally remain weak, but may be sufficient
for development of small outflow-driven clusters capable of
localized severe gusts.

...Northern Lower MI...
Similar to Thursday, a few strong storms may develop this afternoon
and evening across parts of northern lower MI, along the northeast
periphery of the substantial buoyancy reservoir centered over the
central Plains and Midwest. Modest northwesterly flow aloft will
provide sufficient shear for some storm organization, with a threat
for isolated hail and damaging winds.

..Dean/Moore.. 08/08/2025

$$

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ACUS01 KWNS 081250
SWODY1
SPC AC 081248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Fri Aug 08 2025

Valid 081300Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE EASTERN DAKOTAS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Scattered severe thunderstorms are possible later today and tonight
across parts of the northern Plains and Upper Midwest. Scattered
damaging winds, large hail, and a couple tornadoes are possible.

...Northern Plains into the Upper Mississippi Valley...
An extensive MCS which produced numerous severe wind gusts across ND
earlier this morning has recently weakened across northern MN. While
occasional strong to locally damaging gusts may still occur in the
short term, this convection should continue weakening through the
rest of the morning as it moves into a less favorable thermodynamic environment. In the wake of this activity, an upper trough/low will
continue advancing eastward across the northern Rockies/Plains
towards the Upper Midwest through the period. At the surface, a weak
low over central SD this morning should develop northeastward to
northern MN by this evening, while a trailing cold front advances
southward across the northern/central High Plains.

Outflow from the morning convection may act as a pseudo warm front
and focus for renewed intense thunderstorm development later today
across parts of central/northern MN. The southern extent and
location of this boundary by this evening remains somewhat
uncertain. Even so, a rather moist and strongly to extremely
unstable airmass will be present east of the cold front and south of
the outflow boundary by late this afternoon across the upper MS
Valley. It still appears probable that additional surface-based
convection may develop by late afternoon/early evening across
eastern ND/northwest MN and vicinity as large-scale ascent preceding
the upper trough/low overspreads the warm sector.

While stronger flow aloft may tend to lag the surface cold front to
some extent, there should still be sufficient deep-layer shear to
support organized updrafts, including supercells with some large
hail threat. Given a large degree of boundary-parallel flow aloft, a
quick linear transition should occur this evening, with a greater
threat for severe/damaging winds. A narrow window for a couple of
tornadoes may exist across parts of MN, mainly this evening
along/near the residual outflow boundary where effective SRH may
become locally enhanced with a gradual strengthening of a southerly
low-level jet. Otherwise, the threat for damaging winds may continue
through tonight across parts of the upper MS Valley so long as any
MCS that develops can remain surface based. Given the potential
effects of the ongoing morning convection, confidence in a corridor
of more concentrated wind potential remains too low to include
greater severe probabilities with this update.

...High Plains...
Thunderstorms are ongoing this morning along/north of a cold front
in the western Dakotas. This activity may pose an isolated hail
threat given ample MUCAPE and strong deep-layer shear. The potential
for additional thunderstorms this afternoon/evening across the
central High Plains either along or behind the front in a low-level
upslope flow regime remains unclear. A conditional risk for
supercells with associated large hail threat is still apparent, but
overall coverage of intense convection may remain quite isolated.
Farther south across the southern High Plains, high-based convection
is expected to develop this afternoon within a hot and well-mixed
boundary layer. Deep-layer flow and related shear will generally
remain weak, but outflow-driven clusters may still be capable of
localized severe gusts.

...Northern Lower Michigan...
Similar to yesterday, isolated strong to severe thunderstorms may
develop this afternoon and evening across parts of northern Lower MI
and vicinity, along the northeast periphery of the substantial
reservoir of instability over the central Plains and Midwest. Modest northwesterly flow aloft will provide sufficient shear for some
updraft organization, with a threat for occasional hail and damaging
winds.

..Gleason/Leitman.. 08/08/2025

$$

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ACUS01 KWNS 081620
SWODY1
SPC AC 081618

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1118 AM CDT Fri Aug 08 2025

Valid 081630Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO
TONIGHT OVER PARTS THE UPPER MIDWEST....

...SUMMARY...
Scattered severe thunderstorms are possible this evening and
tonight across parts of the Upper Midwest. Scattered damaging winds,
large hail, and a couple tornadoes are possible.

...Upper Midwest...
The large convective complex that affected ND/MN last night has
mostly dissipated, with the associated shortwave trough lifting
across the MN Arrowhead. Shortwave ridging is occurring in the wake
of this system, which should suppress deep convective development
for most of the afternoon. Southeasterly low-level winds and
daytime heating across much of MN and eastern SD will help
re-establish a very moist/unstable air mass (MLCAPE > 4000 J/kg) by
late afternoon.

Another strong shortwave trough now over WY will begin affecting the
ND/MN area by that time, with an associated cold front approaching
the area. Scattered thunderstorms are expected to form along/ahead
of the front, mainly after 00z. Deep-layer shear will support
supercell storm structures capable of large hail and damaging wind
gusts. A few tornadoes are also possible, given the very moist
environment and backed low-level winds. However, many of the storms
may be elevated and behind the front. Activity will persist deep
into the night, spreading eastward across MN and into parts of
northern WI and western Upper MI.

..Hart/Squitieri.. 08/08/2025

$$

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ACUS01 KWNS 081942
SWODY1
SPC AC 081941

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0241 PM CDT Fri Aug 08 2025

Valid 082000Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO
TONIGHT FOR PARTS OF THE UPPER MIDWEST AND THE CENTRAL HIGH
PLAINS...

...SUMMARY...
Scattered severe thunderstorms with damaging winds, large hail, and
a couple tornadoes are possible this evening and tonight across
parts of the Upper Midwest and the central High Plains.

...20z Update...

...Upper Midwest...
Latest radar/satellite trends show a residual storm complex and
cloud cover over northeast Minnesota. This activity continues to
diminish, with some weak convection developing in proximity. Surface observations suggest little evidence of extensive outflow in its
wake, though southeasterly surface winds are prevalent across much
of Minnesota where cloud cover has remained persistent. To the west,
a cold front continues to advance eastward and is beginning to
impinge upon portions of northwest Minnesota into eastern South
Dakota.

Storm initiation is still expected by early evening along the cold
front in eastern South/North Dakota, with a quick transition from
cellular to linear modes. Not much has changed in terms of
expectations from the prior outlook. As this activity grows upscale
and matures, some potential for a more concentrated corridor of
damaging winds may emerge in far northeast Minnesota, but details
remain uncertain and will be reevaluated in the 01z Outlook. With
that said, given the potential for upscale growth, have expanded the
Marginal area (Level 1 of 5) eastward into portions of northeast
Iowa and vicinity.

...Southwest South Dakota/Nebraska Panhandle...
Surface observations and SPC mesoanalysis show a post-frontal
airmass with enough residual moisture to allow for modest
destabilization across the region. Recent CAM guidance suggests the
potential for isolated convection to develop in the high terrain of
eastern Wyoming and persist eastward into southwest South Dakota and
the Nebraska Panhandle. Given effective shear of 45-50 kt in
association with enhanced flow along the southern periphery of the
upper-level trough, a few supercell storms are possible with severe
hail/wind the main threats. Therefore, have introduced a Slight Risk
(Level 2 of 5) to encompass this potential.

..Karstens/Lyons.. 08/08/2025

.PREV DISCUSSION... /ISSUED 1118 AM CDT Fri Aug 08 2025/

...Upper Midwest...
The large convective complex that affected ND/MN last night has
mostly dissipated, with the associated shortwave trough lifting
across the MN Arrowhead. Shortwave ridging is occurring in the wake
of this system, which should suppress deep convective development
for most of the afternoon. Southeasterly low-level winds and
daytime heating across much of MN and eastern SD will help
re-establish a very moist/unstable air mass (MLCAPE > 4000 J/kg) by
late afternoon.

Another strong shortwave trough now over WY will begin affecting the
ND/MN area by that time, with an associated cold front approaching
the area. Scattered thunderstorms are expected to form along/ahead
of the front, mainly after 00z. Deep-layer shear will support
supercell storm structures capable of large hail and damaging wind
gusts. A few tornadoes are also possible, given the very moist
environment and backed low-level winds. However, many of the storms
may be elevated and behind the front. Activity will persist deep
into the night, spreading eastward across MN and into parts of
northern WI and western Upper MI.

$$

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ACUS01 KWNS 090101
SWODY1
SPC AC 090059

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Fri Aug 08 2025

Valid 090100Z - 091200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN SD
INTO MN AND NORTHWEST WI...AND ALSO ACROSS SOUTHWEST SD AND WESTERN
NE...

...SUMMARY...
Scattered severe thunderstorms with damaging winds, large hail, and
possibly a tornado are expected to develop this evening and tonight
across parts of the Upper Midwest and the central High Plains.

...Eastern Dakotas into MN/northwest WI...
Scattered to widespread storm development is still expected later
this evening from the far eastern Dakotas into MN, as a seasonably
deep mid/upper-level shortwave trough and attendant cold front
impinge upon a strongly unstable environment. A few supercells could
evolve initially within a moderately sheared environment, with a
threat of hail and possibly a tornado. Deep-layer flow/shear
generally parallel to the front will likely result in a quick
transition to a cluster or linear mode. This could lead to an
increasing threat for damaging wind, though there may be some
tendency for convection to become slightly anafrontal with time.

Guidance suggests the greatest relative threat for more organized
upscale growth will be from central into northeast MN, along a
diffuse surface boundary. The late timing and the effects of
nocturnal low-level stabilization results in some uncertainty
regarding the magnitude of the severe-wind threat, but a swath of
damaging wind remains possible into the overnight hours.

...Central Plains vicinity...
Development of a supercell or two remains possible this evening
within a post-frontal regime from southwest SD into western NE,
though coverage remains uncertain. Elongated hodographs would
support a hail threat with any sustained cells, with localized
severe gusts also possible.

Some recent runs of the HRRR suggest post-frontal development
overnight across parts of southeast WY and northeast CO. While this
scenario is uncertain, the environment will be favorable for
isolated hail and strong gusts if storms develop.

A nebulous but potentially organized severe threat also remains
evident overnight across parts of NE into northern IA, within a
favorably unstable and modestly sheared environment. Strong elevated
storms will be possible as the front moves into the region, with
some threat for hail and localized damaging winds. Any organized
clustering could result in a locally greater damaging-wind threat.

...Northern Lower MI...
A strong storm or two remains possible this evening across northern
Lower MI, before convection wanes later tonight as CINH increases.
Steep lapse rates, moderate buoyancy, and around 30 kt of effective
shear (as noted on the 00Z APX sounding) could continue to support a
threat of isolated hail and strong gusts before storms diminish with
time.

..Dean.. 08/09/2025

$$

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ACUS01 KWNS 090601
SWODY1
SPC AC 090559

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1259 AM CDT Sat Aug 09 2025

Valid 091200Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM FAR EASTERN
NE INTO IA/WI...NORTHERN MO/IL AND SOUTHERN UPPER MI...AND ALSO
ACROSS EASTERN CO...

...SUMMARY...
Multiple damaging wind swaths are possible later today into tonight,
centered on parts of Wisconsin, Iowa, and northwest Illinois.
Multiple rounds of large hail are possible across eastern Colorado
starting in the late afternoon.

...Upper Great Lakes into the lower MO Valley...
Prior to the start of the forecast period, extensive convection is
expected to develop across MN early this morning, in association
with a seasonably strong mid/upper-level trough. A separate
organized storm cluster may develop across the central Plains and
approach parts of the MO Valley by 12Z this morning. Evolution of
the morning convection is uncertain, but there will be some
possibility for intensification as storms move eastward into a
potentially destabilizing airmass. Should this occur, a swath of
damaging wind will be possible across parts of WI and northwest IL
later today. Also, depending on the southern extent of convection
this morning, any organized cluster emerging from the central Plains
could continue through the day across parts of IA, with a threat of
damaging wind and hail.

In the wake of early-day convection, an outflow-reinforced surface
boundary may become quasi-stationary somewhere from the central
Plains into parts of the Midwest, though uncertainty remains
regarding the position of this boundary by late afternoon. Renewed
storm development will be possible near the boundary, within a
strongly unstable environment. While some weakening of deep-layer
flow may occur, effective shear will remain sufficient for organized convection. Initial supercell development is possible near the
boundary, with a threat of isolated hail and possibly a tornado.
Upscale growth into one or more clusters will be possible during the
evening, in association with a nocturnally strengthening low-level
jet. This could support another round of damaging-wind potential.

...Central/southern High Plains...
A cold front may become quasi-stationary by this afternoon across
the south-central High Plains. A favorable post-frontal regime for
severe storms is expected to develop across eastern CO. Steep
midlevel lapse rates, moderate instability, and favorable deep-layer
shear will support scattered supercells capable of large to very
large hail, localized severe gusts, and possibly a tornado, mainly
this afternoon into the evening.

Farther south, high-based convection may again develop across parts
of eastern NM into the TX/OK Panhandles, which could pose a threat
of localized severe gusts.

..Dean/Moore.. 08/09/2025

$$

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ACUS01 KWNS 091249
SWODY1
SPC AC 091248

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0748 AM CDT Sat Aug 09 2025

Valid 091300Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE UPPER GREAT LAKES/UPPER MIDWEST...AND EASTERN COLORADO INTO FAR
WESTERN KANSAS...

...SUMMARY...
Multiple severe/damaging wind swaths should occur today centered on
parts of Iowa, northwest Illinois, Wisconsin, and the Upper
Peninsula of Michigan. Large to very large hail will be possible
across parts of eastern Colorado and vicinity this afternoon and
evening.

...Upper Great Lakes/Upper Midwest into the Missouri Valley...
A small but intense bowing cluster has produced numerous severe
gusts/damage reports (some 75+ mph) in a narrow corridor early this
morning across south-central NE to western IA. This convection
should continue east-northeastward across parts of central/northern
IA through the rest of the morning, with an enhanced southwesterly
low-level jet providing ample moist inflow. A very unstable airmass
remains in place ahead of a cold front across this area, with MUCAPE
around 3000-3500 J/kg. This large reservoir of buoyancy should
continue to support a severe/damaging wind threat with this cluster
into parts of central/northern IA for at least the next few hours.
See Mesoscale Discussion 1911 for more details on the short-term
severe threat associated with this bowing complex.

Additional thunderstorms have developed along/near the cold front
across a broader portion of the Upper Great Lakes and Upper Midwest.
It still appears probable that multiple swaths of severe/damaging
winds may occur through the afternoon and evening across parts of
these regions as the airmass ahead of these thunderstorms gradually destabilizes. With rich low-level moisture already in place, strong
to extreme instability should once again develop by this afternoon.
While stronger mid-level flow and related deep-layer shear will tend
to lag the cold front, they should still be sufficient to support
organized convection, mainly linear clusters. Some adjustments have
been made to the Slight Risk to account for the ongoing severe
thunderstorms in IA, as well as additional activity forecast to
occur through the afternoon and evening. The potential for
additional robust convective development tonight across parts of the
MO Valley remains unclear as a southerly low-level jet strengthens
once again. Regardless, have maintained severe probabilities across
southeast NE and vicinity for this possibility.

...Central/Southern High Plains...
A cold front should become nearly stationary by this afternoon
across the south-central High Plains. A favorable low-level,
post-frontal regime for severe convection is expected to develop
across eastern CO by late afternoon. The presence of steep mid-level
lapse rates, moderate instability, and favorable deep-layer shear
will likely support scattered supercells capable of large to very
large hail, localized severe gusts, and possibly a tornado or two
mainly this afternoon into the evening. Across the southern High
Plains, high-based convection may again develop across parts of
eastern NM into the OK/TX Panhandles. This activity could pose a
isolated threat for severe gusts given a very well-mixed boundary
layer.

..Gleason/Leitman.. 08/09/2025

$$

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ACUS01 KWNS 091623
SWODY1
SPC AC 091622

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1122 AM CDT Sat Aug 09 2025

Valid 091630Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM EASTERN
COLORADO ACROSS THE CENTRAL PLAINS INTO THE WESTERN GREAT LAKES
REGION...

...SUMMARY...
Scattered strong/severe storms are possible this afternoon and
tonight from eastern Colorado eastward across the Central Plains
into the western Great Lakes. Isolated damaging wind gusts are
possible in southeast Arizona.

...IA/WI Vicinity...
An intense small-scale MCS affected parts of eastern NE and western
IA overnight and this morning. The remnants of this system are
moving across eastern IA and have weakened below severe limits.
This activity will likely persist eastward across WI and into parts
of Upper MI through the day, but a sagging cold front ahead of the
storms coupled with some cloud cover limit the confidence it can
re-intensify to severe levels. Nevertheless will maintain a SLGT
risk for the areas ahead of this activity.

...NE/MO/IA tonight...
Substantial airmass stabilization has occurred across this area in
the wake of the overnight storms. It appears likely that relatively
strong heating and return of a very moist air mass will result in
strong CAPE values by early evening. A strengthening low-level jet
will enhance lift along the retreating outflow boundary, likely
resulting in rapid thunderstorm development after 00z over northeast
KS. These storms will build east-northeastward into southern
IA/northern MO through the evening/night with a risk of upscale
organization and damaging winds/hail.

...CO/NE/KS...
Southeasterly low-level winds will help maintain a very
moist/unstable air mass over eastern CO this afternoon, with
dewpoints in the 60s and MLCAPE values of 2500+ J/kg. Present
indications are that thunderstorms will form off the Palmer Ridge by mid-afternoon and spread eastward toward western KS this evening.
Forecast soundings show an environment favorable for supercell
structures. Very large hail, damaging winds, and a tornado or two
are possible. This activity may persist into the night, spreading
eastward across central KS.

After dark, persistent southeasterly low-level winds into the
foothills of central/southern CO will interact with an approaching
shortwave trough to pose the risk of continued re-development of
strong/severe storms, with very large hail possible.

...Southeast AZ...
Considerable low/mid level moisture are present today over parts of
southeast AZ and southwest NM, with dewpoints in the low 60s. Full
sunshine will result in scattered afternoon thunderstorms over the
higher terrain that will propagate westward during the evening.
Locally damaging wind gusts are possible.

..Hart/Marsh.. 08/09/2025

$$

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ACUS01 KWNS 091958
SWODY1
SPC AC 091957

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Sat Aug 09 2025

Valid 092000Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM THE FRONT
RANGE TO THE CENTRAL PLAINS AND WESTERN GREAT LAKES....

...SUMMARY...
Scattered strong/severe storms are possible through tonight from
eastern Colorado, across the Central Plains and into the western
Great Lakes. Isolated damaging wind gusts are possible in southeast
Arizona.

...20z Update Western Great Lakes...
A large convective complex remains ongoing as of this afternoon from
portions of eastern WI, into eastern IA and northern MO. Diurnal
heating ahead of the remnant storms and outflow should promote some redevelopment/organization this afternoon and evening. Behind the
system, widespread cloud cover and precipitation has largely
overturned the air mass. This suggests little if any redevelopment
and severe risk is expected. The Slight Risk for damaging gusts will
be maintained ahead of the ongoing storms, with severe probabilities
removed where air mass recovery is unlikely in the wake of the
complex. See MCD#1914 for short-term guidance.

..Central Plains to Midwest...
On the southwestern flank of the ongoing convective complex over the
Upper Midwest, gradual air mass recovery is ongoing ahead of a
slow-moving cold front, likely continuing into this evening.
Afternoon model guidance shows an increase in low-level warm air
advection from a 35-50 kt low-level jet is likely along the front
and prior outflow intersection across southeast NE and northwest KS.
The increase in ascent should foster widespread thunderstorms after
dark across the central Missouri Valley. Very large, but likely
elevated, CAPE along the boundary (3500+ J/kg) should support one or
more clusters with damaging winds and some hail potential tonight.
Minor changes were made to the Slight Risk area to better align with
current frontal position and guidance.

...Front Range...
Confidence continues to increase that upslope flow and the passage
of a mid-level trough should support scattered thunderstorms,
including supercells, in several rounds through tonight. Storms
should continue developing this afternoon off the higher terrain
over eastern CO/WY. Moderate buoyancy, steep lapse rates and 40+ kt
of deep-layer shear suggests hail (some potentially 2+ inch) will be
likely along with the potential for damaging gusts and a tornado or
two. Minimal changes were made to this outlook area for the latest
guidance, see MCD#1913 for short-term info.

..Lyons.. 08/09/2025

.PREV DISCUSSION... /ISSUED 1122 AM CDT Sat Aug 09 2025/

...IA/WI Vicinity...
An intense small-scale MCS affected parts of eastern NE and western
IA overnight and this morning. The remnants of this system are
moving across eastern IA and have weakened below severe limits.
This activity will likely persist eastward across WI and into parts
of Upper MI through the day, but a sagging cold front ahead of the
storms coupled with some cloud cover limit the confidence it can
re-intensify to severe levels. Nevertheless will maintain a SLGT
risk for the areas ahead of this activity.

...NE/MO/IA tonight...
Substantial airmass stabilization has occurred across this area in
the wake of the overnight storms. It appears likely that relatively
strong heating and return of a very moist air mass will result in
strong CAPE values by early evening. A strengthening low-level jet
will enhance lift along the retreating outflow boundary, likely
resulting in rapid thunderstorm development after 00z over northeast
KS. These storms will build east-northeastward into southern
IA/northern MO through the evening/night with a risk of upscale
organization and damaging winds/hail.

...CO/NE/KS...
Southeasterly low-level winds will help maintain a very
moist/unstable air mass over eastern CO this afternoon, with
dewpoints in the 60s and MLCAPE values of 2500+ J/kg. Present
indications are that thunderstorms will form off the Palmer Ridge by mid-afternoon and spread eastward toward western KS this evening.
Forecast soundings show an environment favorable for supercell
structures. Very large hail, damaging winds, and a tornado or two
are possible. This activity may persist into the night, spreading
eastward across central KS.

After dark, persistent southeasterly low-level winds into the
foothills of central/southern CO will interact with an approaching
shortwave trough to pose the risk of continued re-development of
strong/severe storms, with very large hail possible.

...Southeast AZ...
Considerable low/mid level moisture are present today over parts of
southeast AZ and southwest NM, with dewpoints in the low 60s. Full
sunshine will result in scattered afternoon thunderstorms over the
higher terrain that will propagate westward during the evening.
Locally damaging wind gusts are possible.

$$

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ACUS01 KWNS 100106
SWODY1
SPC AC 100104

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0804 PM CDT Sat Aug 09 2025

Valid 100100Z - 101200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
CENTRAL PLAINS AND MIDWEST...

...SUMMARY...
Scattered strong/severe storms remain possible tonight from eastern
Colorado into parts of the Central Plains and Midwest.

...Central Plains into parts of IA/MO/IL...
Widely scattered supercells are ongoing this evening across parts of
eastern CO, within a moderately unstable and favorably sheared
environment. Moist low-level post-frontal flow may continue to
support redevelopment of cells across eastern CO through the
evening, with a continued threat of large hail, localized severe
gusts, and possibly a tornado.

Farther east, ongoing convection may increase in coverage and spread
eastward through the evening into parts of western/central NE and
KS, generally along and north of a surface boundary draped across western/northern KS. Strong instability remains in place near/north
of this boundary, and moderate midlevel westerlies atop low-level
easterly winds are resulting in sufficient effective shear (40-50
kt) for storm organization. Storm clustering and MCS development
will be possible later this evening, with an increasing threat for
severe wind gusts, potentially near/above 75 mph.

Another area of potential development this evening is near the
surface boundary in the northeast KS/southeast NE vicinity,
supported by a nocturnally increasing low-level jet. Initial
development could evolve into a few supercells, capable of large to
very large hail, localized gusty winds, and possibly a tornado. The
increasing nocturnal low-level jet could also support some
clustering of initial discrete cells, and/or maintenance of a
possible MCS approaching from the west. This could result in an
overnight threat for damaging wind across eastern NE/northeast KS
into parts of IA and northern MO.

Finally, strong to locally severe storms remain possible this
evening from northeast MO into northern IL, within a very moist and
strongly unstable environment. Deep-layer shear is weaker compared
to areas farther west, but locally damaging wind and perhaps some
hail will be possible with the strongest storms. Recent HRRR/RRFS
guidance suggests that, if an MCS develops tonight over the central
Plains, it may reach as far as eastern IA/western IL by 12Z Sunday
morning, with some wind-damage potential.

...Southeast AZ...
A few strong storms remain possible into this evening across parts
of southeast AZ, within a moderately unstable environment. Localized
strong gusts will remain possible before a general weakening trend
later this evening.

..Dean.. 08/10/2025

$$

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ACUS01 KWNS 100602
SWODY1
SPC AC 100600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Sun Aug 10 2025

Valid 101200Z - 111200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
CENTRAL HIGH PLAINS...

...SUMMARY...
Scattered severe storms are possible across parts of the central
High Plains later today into tonight. Other strong to potentially
severe storms may occur from the southern High Plains into parts of
the Midwest and Great Lakes.

...Central/southern High Plains vicinity...
In the wake of extensive antecedent convection, moisture and
instability may be somewhat weaker (compared to Saturday) within the post-frontal regime across the central High Plains later today.
However, midlevel lapse rates will remain steep, with sufficient
moisture for moderate destabilization this afternoon from near the
CO Front Range southward to the lee of the Sangre de Cristo
mountains. A midlevel shortwave moving through the base of a
positively tilted trough across the northern/central Rockies/High
Plains will aid in scattered storm development this afternoon.
Veering wind profiles will support effective shear of 30-40 kt,
sufficient for initial supercell potential and a threat for hail,
localized strong to severe gusts, and possibly a tornado. Most
guidance suggests some potential for upscale growth into the
south-central High Plains by evening, accompanied by a threat for
one or more corridors of strong to severe gusts.

...Eastern KS/northeast OK into parts of the Midwest...
A remnant MCS may be ongoing at the start of the forecast period
across parts of IA and northern MO. Most guidance suggests this
system will tend to weaken with time, as it encounters weaker
instability and deep-layer shear. Some threat for isolated damaging
wind could persist into the early part of the forecast period.

An outflow-influenced surface boundary will be left in the wake of
this MCS across parts of central/southern KS into MO, though
guidance varies regarding the position of this boundary by
afternoon. Guidance also varies regarding the potential for diurnal redevelopment in the vicinity of this boundary, but moderate to
strong buoyancy could support vigorous updrafts if any storms can be
sustained. Deep-layer flow/shear may remain relatively weak, but at
least some potential for hail and damaging wind could evolve during
the afternoon and evening.

Farther north, the MCV associated with the decayed MCS will move
northeastward toward parts of the Upper Midwest and Great Lakes.
This MCV may be accompanied by modestly enhanced low/midlevel flow,
and recent HRRR guidance suggests some potential for storms with
localized damaging winds later today across parts of the Midwest and
Great Lakes, in conjunction with the MCV.

...Southeast AZ...
Scattered storms will again be possible this afternoon across parts
of southeast AZ and vicinity, within a relatively moist and
moderately unstable environment. Locally gusty winds will be
possible, though in the absence of stronger midlevel flow, potential
for more than very isolated severe gusts remains uncertain at this
time.

..Dean/Moore.. 08/10/2025

$$

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ACUS01 KWNS 101236
SWODY1
SPC AC 101234

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Sun Aug 10 2025

Valid 101300Z - 111200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL/SOUTHERN PLAINS...

...SUMMARY...
Scattered severe thunderstorms are possible across parts of the central/southern Plains today and tonight, with large hail and
damaging winds the main threats. Strong to severe thunderstorms may
also occur from parts of the Midwest to the upper Great Lakes.

...Eastern Kansas/Missouri/Iowa to the Upper Great Lakes...
Loosely organized convection is ongoing this morning across parts of
eastern IA, aided by modest low-level warm advection and a MCV.
While this activity has generally remained sub-severe for the past
few hours, there is some potential for gradual re-intensification
through the afternoon as the MCV tracks northeastward across parts
of the Upper Midwest. While cloud cover is noted downstream per
early-morning visible satellite imagery, filtered daytime heating
should encourage the development of weak to locally moderate
instability by early to mid afternoon over portions of WI and
vicinity ahead of a weak front. It remains unclear whether a bowing
cluster will be able to form later today, but isolated damaging
winds may occur if it develops and can persist.

Farther south across eastern KS into MO, ongoing thunderstorms are
occurring generally to the north of a convectively reinforced
outflow boundary/front. While this elevated activity could pose an
isolated hail/wind threat this morning, it is generally forecast to
diminish by late morning as a southwesterly low-level jet gradually
weakens. However, additional thunderstorm development may occur this afternoon/evening along and south of the outflow boundary in MO as
daytime heating of a rather moist low-level airmass supports
moderate to strong instability. Deep-layer shear will remain weak
across this area, but occasional severe/damaging gusts could still
occur given the large degree of buoyancy forecast.

...Central/Southern Plains...
Extensive convective overturning yesterday/early this morning should
result in a less unstable post-frontal airmass across the
central/southern High Plains compared to Saturday. Even so, steep
mid-level lapse rates emanating from the Southwest should once again
overspread a modestly moist low-level airmass this afternoon. This
will foster the development of weak to moderate instability in
tandem with daytime heating. Thunderstorms will likely develop over
the higher terrain/CO Front Range by early afternoon as a weak
mid-level shortwave trough presently over eastern UT/western CO
moves eastward. Sufficient deep-layer shear for organized updrafts
is forecast, including the potential for a few supercells with
associated threat for mainly large hail, and perhaps a tornado.

With time, clustering should occur over the central/southern High
Plains along and perhaps a bit north of the convectively reinforced front/outflow boundary. Ample MUCAPE, steepened lapse rates aloft,
and a modest southerly low-level jet should support some threat for
severe gusts with one or more clusters that may spread eastward this
evening and overnight. Have expanded the Slight Risk eastward across
parts of western/central KS, the adjacent OK/TX Panhandles, and
northwest OK based on a consensus of recent model guidance showing
this potential.

..Gleason/Leitman.. 08/10/2025

$$

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ACUS01 KWNS 101622
SWODY1
SPC AC 101621

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1121 AM CDT Sun Aug 10 2025

Valid 101630Z - 111200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT OVER PORTIONS OF THE CENTRAL AND SOUTHERN PLAINS...

...SUMMARY...
Scattered severe thunderstorms are possible across parts of the central/southern Plains today and tonight, with large hail and
damaging winds the main threats.

...CO/KS...
Morning water vapor loop shows a vigorous shortwave trough digging southeastward into central CO. Large scale forcing for ascent ahead
of this trough will aid in the development of scattered
thunderstorms along the foothills of central CO by early afternoon,
with storms spreading eastward through the afternoon/evening. Ample
low-level moisture and CAPE are present over eastern CO/western KS
to promote a few intense cells, with favorable westerly flow aloft
for supercell structures. Large hail is the main concern, with an
increasing risk of damaging winds with eastward extent this evening.
A tornado or two is possible as storms interact with a remnant
outflow boundary that extends across the TX Panhandle and northwest
OK.

...MO/IL/WI...
A corridor of strong heating will encourage scattered thunderstorm
development this afternoon from southern MO into central/northeast
IL. Weak winds aloft and considerable mid-level moisture will limit
overall downdraft potential. Nevertheless, gusty/damaging winds
could occur with the strongest cells.

...Southeast AZ...
Similar to yesterday, scattered high-based afternoon/evening
thunderstorm development is expected over southeast AZ in a
hot/unstable environment. The strongest cells may produce locally
damaging wind gusts.

..Hart/Squitieri.. 08/10/2025

$$

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ACUS01 KWNS 101957
SWODY1
SPC AC 101956

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Sun Aug 10 2025

Valid 102000Z - 111200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE CENTRAL AND SOUTHERN PLAINS...

...SUMMARY...
Scattered severe thunderstorms are possible across parts of the central/southern Plains through tonight, with large hail and
damaging winds the main threats.

...20z Update Front Range...
Initial thunderstorms should continue to develop over the higher
terrain of eastern CO and the Front Range as a broad upper trough
shifts eastward and low-level upslope flow continues this afternoon.
1500 J/kg of MLCAPE and westerly flow aloft around 35-45 kt will
support supercells. Steep mid-level lapse rates and cooler mid-level temperatures will favor an initial risk for hail before upscale
growth results in an MCS tonight. Damaging gusts are possible into
parts of the southern Plains. Have expanded the Slight Risk farther
north/east where development is possible closer to the WY/CO border.


...Mid Mississippi Valley...
Diurnal heating ahead of the weak cold front over the Midwest will
continue to support moderate destabilization this afternoon. Ongoing thunderstorm clusters should gradually expand eastward as cold pools
deepen. While vertical shear will not be strong, (generally less
than 20 kt) an occasional damaging gust remains possible over parts
of IL, MO and WI. Have expanded the Marginal risk eastward to cover
the low-end risk. Otherwise, see the prior outlook for additional
info.

..Lyons.. 08/10/2025

.PREV DISCUSSION... /ISSUED 1121 AM CDT Sun Aug 10 2025/

...CO/KS...
Morning water vapor loop shows a vigorous shortwave trough digging southeastward into central CO. Large scale forcing for ascent ahead
of this trough will aid in the development of scattered
thunderstorms along the foothills of central CO by early afternoon,
with storms spreading eastward through the afternoon/evening. Ample
low-level moisture and CAPE are present over eastern CO/western KS
to promote a few intense cells, with favorable westerly flow aloft
for supercell structures. Large hail is the main concern, with an
increasing risk of damaging winds with eastward extent this evening.
A tornado or two is possible as storms interact with a remnant
outflow boundary that extends across the TX Panhandle and northwest
OK.

...MO/IL/WI...
A corridor of strong heating will encourage scattered thunderstorm
development this afternoon from southern MO into central/northeast
IL. Weak winds aloft and considerable mid-level moisture will limit
overall downdraft potential. Nevertheless, gusty/damaging winds
could occur with the strongest cells.

...Southeast AZ...
Similar to yesterday, scattered high-based afternoon/evening
thunderstorm development is expected over southeast AZ in a
hot/unstable environment. The strongest cells may produce locally
damaging wind gusts.

$$

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ACUS01 KWNS 110102
SWODY1
SPC AC 110101

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0801 PM CDT Sun Aug 10 2025

Valid 110100Z - 111200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS PORTIONS OF THE
CENTRAL HIGH PLAINS TO THE SOUTHERN PLAINS...

...SUMMARY...
Scattered severe thunderstorms are possible across parts of the central/southern Plains tonight, with large hail and damaging winds
the main threats.

...Synopsis...
Latest water-vapor imagery shows a pronounced mid-level perturbation overspreading the central High Plains. Thunderstorm coverage has
increase from western NE southward to eastern NM over the past
several hours in response to increasing ascent over a buoyant air
mass. Additionally, thunderstorm development over the past several
hours has been focused along a residual frontal zone from
north-central OK into southwest MO. Through the remainder of the
night, thunderstorm activity (and most of the appreciable severe
threat) will be focused across the central High Plains to the
southern Plains as thunderstorms migrate out of eastern CO and
develop along the frontal zone.

...Eastern CO to southwest KS/northwest OK...
A band of convection across east-central CO has recently shown signs
of re-intensification over the past 30-60 minutes after a temporary
weakening phase - likely caused by the band impinging on richer
low-level moisture/higher MLCAPE. The recent 00z DDC sounding
sampled the downstream environment well and shows nearly 2000 J/kg
MLCAPE and elongated hodographs supporting 45 knots of effective
bulk shear. This thermodynamic/kinematic environment should support
further intensification/organization as the developing MCS pushes east/southeast through the late evening/overnight hours with an
attendant threat for severe winds. Downstream, additional
development along the effective warm frontal zone is expected in the
coming hours as the nocturnal jet strengthens over north-central OK. Thunderstorms developing within this regime will pose a threat for
severe gusts as well as large hail.

...Southern to southeast WI...
An MCV that developed across eastern IA late this afternoon
continues to push northeast into southwest WI as of 01z. GOES
imagery and lightning data have shown a slight uptick in intensity
over the past hour, and RAP mesoanalysis estimates show meager
recovery of low-level moisture/MLCAPE downstream of the MCV.
Additionally, the 00z GRB sounding sampled 30-40 knot flow between
700 mb to 400 mb, suggesting that adequate deep-layer shear is in
place to support some storm organization if the intensification
trend can continue. That said, the window for any severe threat may
be limited to the next few hours before nocturnal cooling begins to
increase low-level inhibition.

...Southeast AZ...
Isolated thunderstorms continue to percolate within the higher
terrain of southeast AZ. While much of this activity has struggled
to move off the terrain, latest CAM guidance suggests storms may
begin to spread south as the mid-level perturbation passes to the
northeast. With a hot/dry and deeply mixed environment still in
place across southern/southeast AZ (e.g. the recent 00z TUS
sounding), a few damaging to severe wind gusts will remain possible
prior to the onset of nocturnal cooling in a few hours.

..Moore.. 08/11/2025

$$

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ACUS01 KWNS 110542
SWODY1
SPC AC 110541

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1241 AM CDT Mon Aug 11 2025

Valid 111200Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN HIGH PLAINS AND RED RIVER VALLEY OF THE NORTH...

...SUMMARY...
Strong thunderstorms accompanied by at least some risk for severe
wind and hail may impact parts of eastern New Mexico into the Texas
South Plains, as well as parts of eastern North Dakota into
northwestern Minnesota, late this afternoon and evening.

...Synopsis...
Late-evening water-vapor imagery depicts an upper trough/vorticity
maximum settling into the southern/central High Plains. This feature
is expected to stall and weaken over the Plains over the next 24
hours with a gradual abatement of mid-level flow. To the north, a
pronounced mid-level wave is apparent over the Canadian
Rockies/Prairies. This feature will continue southeastward into the
northern Plains and upper Mississippi River Valley through tonight. Strong/severe thunderstorm chances will largely be attendant to
these mid-level features.

...Southern High Plains...
05z surface observations across the southern Plains reveal a
composite frontal zone/outflow boundary draped from far northeast NM
through the TX/OK Panhandles and roughly along the OK/KS border.
This boundary will likely be displaced southward as a result of
early-morning convection, though precisely where this boundary
resides by peak heating is somewhat uncertain. Regardless,
thunderstorm development along this boundary is expected by late afternoon/early evening. To the south of this boundary, easterly
winds on the northern periphery of a weak surface low over the
Permian Basin will maintain an upslope flow regime along the eastern
slopes of the Sacramento, Sandia Manzano, and Sangre de Cristo
Mountains. Modest westerly mid-level flow atop easterly low-level
winds should yield sufficient deep-layer shear for a few organized
storms, including a supercell or two. With time, upscale growth
and/or merging with additional convection developing along the
surface boundary will promote an increased threat for severe gusts
through early evening. While convection is expected northeastward
along much of the boundary from central OK into adjacent portions of
KS/MO, weaker mid-level winds with eastward extent casts doubt on
the potential for a robust severe threat (aside from occasional
strong wet downbursts).

...Red River Valley of the North...
Modest surface cyclogenesis is anticipated across the central
Canadian Prairies over the next 24 hours as the mid-level wave
approaches the international border. An attendant cold front is
forecast to spread across the northern Plains through late afternoon
and will impinge on a plume of seasonal low-level moisture. While
mid-level lapse rates will remain modest (around 6-7 C/km), adequate
buoyancy should be in place for deep convection. 30-40 knot
mid-level flow should provide sufficient deep-layer shear for
organized storms, though the marginal thermodynamic environment will
likely be a modulating factor in overall storm intensity. Strong
frontal forcing should promote upscale growth through the evening
hours with an associated threat for damaging/severe winds.

..Moore/Darrow.. 08/11/2025

$$

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ACUS01 KWNS 111248
SWODY1
SPC AC 111246

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0746 AM CDT Mon Aug 11 2025

Valid 111300Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE SOUTHERN PLAINS...AND OVER PORTIONS OF NORTH DAKOTA INTO
NORTHERN MINNESOTA...

...SUMMARY...
Isolated strong to severe thunderstorms may pose some risk for
severe winds and hail across parts of the southern Plains, and
separately from North Dakota into northern Minnesota, mainly this
afternoon and evening.

...Southern Plains...
Convection has generally weakened this morning across eastern KS,
with a outflow reinforced front advancing southward across the
southern High Plains. This boundary is forecast to stall through the
morning and early afternoon, and it will likely serve as a focus for
renewed thunderstorm development later today. The southern extent of
upper troughing that exists over much of the Plains is forecast to
advance eastward across the southern High Plains this afternoon.
Initial development over the higher terrain of north-central into
northeast NM should occur in a modest low-level upslope flow regime,
with steep lapse rates aloft contributing to moderate instability.
Weak low-level winds will gradually veer to west-northwesterly and
modestly strengthen with height through mid/upper levels, supporting
modest deep-layer shear and some updraft organization.

Isolated severe hail may occur with initially more cellular
development across the southern High Plains, before some clustering
potentially occurs late this afternoon/evening farther east into the
TX Panhandle and northwest TX with more of a wind threat. While
deep-layer shear will likely remain weak farther east across OK, the front/outflow boundary should aid in at least scattered
thunderstorms developing with moderate to locally strong instability
amid ample daytime heating. Isolated damaging winds via strong
downbursts and marginally severe hail appear possible with the
stronger cores given seasonably cool temperatures aloft (around -10C
at 500 mb with the 12Z OUN observed sounding), and the Marginal Risk
has been expanded eastward for this possibility.

...North Dakota into Northern Minnesota...
Within upper troughing already established over the northern/central
Plains and central Canada, a mid-level shortwave trough and related
surface cold front are forecast to move east-southeastward over ND
and northern MN through the period. Modest low-level moisture
characterized by mid 50s to perhaps low 60s surface dewpoints should
be present ahead of the front across these areas. Diurnal heating
and modestly steepened lapse rates aloft should aid in the
development of weak instability this afternoon. Thunderstorms should
gradually increase in coverage along/ahead of the front this
afternoon/evening as they spread eastward over parts of ND into
northern MN. The stronger cells may produce marginally severe hail,
with sufficient deep-layer shear present for some convective
organization. With time, some clustering/upscale growth along the
front appears probable, with isolated strong to severe gusts
possible. The lack of stronger instability should tend to temper the
overall severe threat.

...Missouri/Iowa...
An MCV generated by overnight/early morning convection across the southern/central Plains should develop northeastward into parts of
northern MO and IA by this afternoon. It remains unclear whether
sufficient instability to support robust thunderstorms will be able
to develop today ahead of this feature given ongoing convection and
cloud debris. Regardless, some enhancement to the low/mid-level flow
and related deep-layer shear could support updraft organization if surface-based thunderstorms can develop. Given the continued
uncertainty regarding this potential, have held off on inclusion of
low severe probabilities across this region with this update.

..Gleason/Leitman.. 08/11/2025

$$

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ACUS01 KWNS 111614
SWODY1
SPC AC 111612

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1112 AM CDT Mon Aug 11 2025

Valid 111630Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE SOUTHERN GREAT PLAINS...LOWER MISSOURI VALLEY...AND UPPER
MIDWEST...

...SUMMARY...
Isolated strong to severe thunderstorms are possible across parts of
the southern Plains, lower Missouri Valley, and the Upper Midwest,
mainly this afternoon and evening.

...Lower MO Valley...
Visible satellite/radar composite shows an MCV moving
east-northeastward over northeast KS late this morning. Regional
WSR-88D VAD data shows an enhanced belt of 850-500 mb flow (40 kt in
the 2-6 km layer) associated with this disturbance. Surface
analysis places a surface low over the Flint Hills with backed
easterly flow across eastern KS into northwest MO. Considerable
mid- to high-level cloud debris from early morning convection will
be slow to dissipate, but gradual filtering of sunlight and the
initial signs of a stratocumulus field over the Flint Hills
indicates destabilization is beginning to occur. Models vary
considerably (understandably so) regarding the development/evolution
of a few potential stronger thunderstorms across the lower MO Valley
later this afternoon into the early evening. Some forecast
soundings show modest enlargement of the low-level portion of the
hodograph, which may support updraft rotation if vigorous updraft
development occurs. Given the low probability for severe and
potentially supportive environment, have introduced low-severe
probabilities this outlook update.

...Southern Plains...
Morning analysis shows an outflow reinforced front has advanced
southward across the southern High Plains, but has stalled near the
I-44 corridor in OK southwestward into the northern periphery of the
Permian Basin. Water-vapor imagery shows a mid-level impulse moving
across southern CO and embedded within larger-scale troughing from
CO/NM into the Upper Midwest. This mid-level trough will gradually
pivot eastward over the southern High Plains through the evening.
Heating of an adequately moist boundary layer (dewpoints ranging
from the lower 70s in central OK to the mid 50s in east-central NM)
will yield moderate buoyancy near/north of the diffuse boundary.
Weak low-level winds will gradually veer to west-northwesterly and
modestly strengthen with height through mid/upper levels, supporting
modest deep-layer shear and some updraft organization.

Isolated severe hail may occur with initially more cellular
development across the southern High Plains, before some clustering
potentially occurs late this afternoon/evening farther east into the
TX Panhandle and northwest TX with more of a wind threat. While
deep-layer shear will likely remain weak farther east across OK, the front/outflow boundary should aid in at least scattered
thunderstorms. Isolated large hail and severe gusts are the primary
hazards with the stronger thunderstorms.

...North Dakota into Northern Minnesota...
No change in thinking from the previous forecast. A mid-level
shortwave trough and related surface cold front are forecast to move east-southeastward over ND and northern MN through the period.
Modest low-level moisture characterized by mid 50s to perhaps low
60s surface dewpoints should be present ahead of the front across
these areas. Diurnal heating and modestly steepened lapse rates
aloft should aid in the development of weak instability this
afternoon. Thunderstorms should gradually increase in coverage
along/ahead of the front this afternoon/evening as they spread
eastward over parts of ND into northern MN. The stronger cells may
produce marginally severe hail, with sufficient deep-layer shear
present for some convective organization. With time, some
clustering/upscale growth along the front appears probable, with
isolated strong to severe gusts possible. The lack of stronger
instability should tend to temper the overall severe threat.

..Smith/Squitieri.. 08/11/2025

$$

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ACUS01 KWNS 111958
SWODY1
SPC AC 111956

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0256 PM CDT Mon Aug 11 2025

Valid 112000Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE SOUTHERN GREAT PLAINS...LOWER MISSOURI VALLEY...AND UPPER
MIDWEST......

...SUMMARY...
Isolated strong to severe thunderstorms are possible across parts of
the southern Plains, lower Missouri Valley, and the Upper Midwest,
mainly this afternoon and evening.

...20Z Update...
Other than updates to the general thunderstorm forecast, the outlook
remains unchanged. See the previous discussion for more details.

..Wendt.. 08/11/2025

.PREV DISCUSSION... /ISSUED 1112 AM CDT Mon Aug 11 2025/

...Lower MO Valley...
Visible satellite/radar composite shows an MCV moving
east-northeastward over northeast KS late this morning. Regional
WSR-88D VAD data shows an enhanced belt of 850-500 mb flow (40 kt in
the 2-6 km layer) associated with this disturbance. Surface
analysis places a surface low over the Flint Hills with backed
easterly flow across eastern KS into northwest MO. Considerable
mid- to high-level cloud debris from early morning convection will
be slow to dissipate, but gradual filtering of sunlight and the
initial signs of a stratocumulus field over the Flint Hills
indicates destabilization is beginning to occur. Models vary
considerably (understandably so) regarding the development/evolution
of a few potential stronger thunderstorms across the lower MO Valley
later this afternoon into the early evening. Some forecast
soundings show modest enlargement of the low-level portion of the
hodograph, which may support updraft rotation if vigorous updraft
development occurs. Given the low probability for severe and
potentially supportive environment, have introduced low-severe
probabilities this outlook update.

...Southern Plains...
Morning analysis shows an outflow reinforced front has advanced
southward across the southern High Plains, but has stalled near the
I-44 corridor in OK southwestward into the northern periphery of the
Permian Basin. Water-vapor imagery shows a mid-level impulse moving
across southern CO and embedded within larger-scale troughing from
CO/NM into the Upper Midwest. This mid-level trough will gradually
pivot eastward over the southern High Plains through the evening.
Heating of an adequately moist boundary layer (dewpoints ranging
from the lower 70s in central OK to the mid 50s in east-central NM)
will yield moderate buoyancy near/north of the diffuse boundary.
Weak low-level winds will gradually veer to west-northwesterly and
modestly strengthen with height through mid/upper levels, supporting
modest deep-layer shear and some updraft organization.

Isolated severe hail may occur with initially more cellular
development across the southern High Plains, before some clustering
potentially occurs late this afternoon/evening farther east into the
TX Panhandle and northwest TX with more of a wind threat. While
deep-layer shear will likely remain weak farther east across OK, the front/outflow boundary should aid in at least scattered
thunderstorms. Isolated large hail and severe gusts are the primary
hazards with the stronger thunderstorms.

...North Dakota into Northern Minnesota...
No change in thinking from the previous forecast. A mid-level
shortwave trough and related surface cold front are forecast to move east-southeastward over ND and northern MN through the period.
Modest low-level moisture characterized by mid 50s to perhaps low
60s surface dewpoints should be present ahead of the front across
these areas. Diurnal heating and modestly steepened lapse rates
aloft should aid in the development of weak instability this
afternoon. Thunderstorms should gradually increase in coverage
along/ahead of the front this afternoon/evening as they spread
eastward over parts of ND into northern MN. The stronger cells may
produce marginally severe hail, with sufficient deep-layer shear
present for some convective organization. With time, some
clustering/upscale growth along the front appears probable, with
isolated strong to severe gusts possible. The lack of stronger
instability should tend to temper the overall severe threat.

$$

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ACUS01 KWNS 120038
SWODY1
SPC AC 120037

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0737 PM CDT Mon Aug 11 2025

Valid 120100Z - 121200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
MIDWEST AND SOUTHERN PLAINS...

...SUMMARY...
Isolated strong to severe thunderstorms remain possible across parts
of the southern Plains and the Upper Midwest this evening.

...01z Update...

Mid-level flow is turning a bit more northwesterly across the
southern High Plains early this evening as upper troughing shifts
into the central Plains. Scattered robust convection is currently
noted across eastern NM-southern TX-Panhandle into portions of OK.
This activity may continue to expand in areal coverage as it
propagates southeast into modest low-level southerly inflow,
especially given the upper support with the slow-moving upper
trough. Gusty winds or hail may continue to be noted with the
strongest storms this evening.

Farther north across the MN region, notable short-wave trough
currently extends from MB into the eastern Dakotas. Latest model
guidance suggests 500mb speed max will translate across ND into
western MN by 12/12z and this feature should continue to encourage
convection along the surface front as it progresses across the Upper
Midwest. Isolated hail/wind threat remain possible with the
strongest storms.

..Darrow.. 08/12/2025

$$

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ACUS01 KWNS 120540
SWODY1
SPC AC 120538

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1238 AM CDT Tue Aug 12 2025

Valid 121200Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE UPPER
GREAT LAKES AND MIDWEST...AND PARTS OF THE SOUTHWEST...

...SUMMARY...
Strong thunderstorms may impact parts of the upper Great Lakes
region. Storms may be accompanied by at least some risk for severe
wind and hail. Gusty winds may also be noted with a few storms over
southeast Arizona and southwest New Mexico.

...Upper Great Lakes/Midwest...

Upper trough, currently located along the Dakotas/MN border, is
forecast to advance into the upper Great Lakes by late afternoon.
Modest mid-level height falls will overspread WI/MI as a weak
surface front settles across the U.P. of MI/WI by peak heating.
While buoyancy is not forecast to be that strong, deep-layer shear
will increase such that storms that evolve along the boundary during
the afternoon will be adequately sheared for at least the potential
for organized updrafts. Some supercell potential exists but the main
risks appear to be gusty winds and hail.

Farther southeast, latest water-vapor imagery depicts a plume of
higher PW extending across the southern Plains-MO-southern Lake MI.
A few weak embedded disturbances are noted along this corridor which
will lift northeast toward lower MI. Scattered thunderstorms should
develop along this corridor by early afternoon as the boundary layer
warms within a weakly capped environment. Although deep-layer flow
is not particularly strong, gusty winds could accompany robust
convection.

...Southeast AZ/Southwest NM...

Strong boundary-layer heating near the international border into
northern Mexico should encourage diurnally driven convection over
the higher terrain later this afternoon. Storms should be more
numerous south of the border, but isolated activity is expected to
evolve over southeast AZ/southwest NM and drift slowly within a weak
flow regime. While PWs are not particularly high for this time of
year, gusty winds could be noted with the most robust convection.

..Darrow/Moore.. 08/12/2025

$$

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ACUS01 KWNS 121150
SWODY1
SPC AC 121148

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0648 AM CDT Tue Aug 12 2025

Valid 121300Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE UPPER GREAT LAKES/MIDWEST...AND PORTIONS OF THE SOUTHWEST...

...SUMMARY...
Strong to occasionally severe thunderstorms may impact parts of the
upper Great Lakes/Midwest today with both damaging winds and hail
possible. Gusty winds may also occur over southeast Arizona and
southwest New Mexico.

...Great Lakes/Midwest...
A band of thunderstorms associated with an MCV tracked northeastward
across parts of IA into northern IL and southern WI early this
morning while remaining mostly sub-severe. Still, there may be some
potential for strong to locally damaging winds with this activity as
it continues northeastward across Lake Michigan into parts of Lower
MI this morning/early afternoon as daytime heating gradually
destabilizes the boundary layer. Otherwise, additional convection
should develop later this afternoon along/ahead of a weak front over
parts of WI and the U.P. of MI as the southern portion of a
mid/upper-level trough moves eastward over the Upper Midwest/Great
Lakes. Instability is forecast to remain fairly modest ahead of the
front, but enough deep-layer shear should exist to support some
organized convection. Initial cells may be capable of producing
marginally severe hail, before clustering potentially increases the
threat for occasional strong to damaging winds.

A separate area of thunderstorms is forecast to develop this
afternoon farther south and ahead of the front from portions of the
Midwest into Lower MI. While this region will have relatively weaker
mid-level westerly flow and related deep-layer shear compared to
locations farther north, greater low-level moisture and instability
are expected to be present. As low-level lapse rates become
steepened with diurnal heating of the moist airmass, loosely
organized clusters may become capable of producing isolated damaging
winds as they spread generally east-northeastward through the
afternoon and early evening.

...Southwest...
Strong daytime heating should encourage diurnally driven convection
over the higher terrain of southeast AZ and southwest NM this
afternoon. With weak flow aloft and negligible shear, thunderstorms
should drift slowly southward. Still, occasional gusty winds may
occur with the more robust convection given steepened lapse rates.

..Gleason/Leitman.. 08/12/2025

$$

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ACUS01 KWNS 121630
SWODY1
SPC AC 121628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Tue Aug 12 2025

Valid 121630Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
THE GREAT LAKES AND SOUTHEAST ARIZONA INTO SOUTHWEST NEW MEXICO...

...SUMMARY...
Strong to locally severe thunderstorms are possible over parts of
the Great Lakes/Midwest this afternoon with both damaging winds and
hail possible. Gusty winds may also occur over southeast Arizona
and southwest New Mexico.

...Great Lakes/Midwest...
Midday satellite/radar composite show a weakened thunderstorm band
moving east-northeast across the eastern part of Lower MI. Surface
analysis indicates rain-cooled air north of a gust front/outflow
that has become draped from southeast Lower MI into the Michiana
region. Heating south of this boundary has resulted in temperatures
warming through the mid-upper 80s with dewpoints in the lower 70s.
Additional storms will probably develop along the trailing outflow
and gradually move east-northeast with the mean wind. Considerably
weaker deep-layer shear is present across the eastern part of the
Corn Belt into the Lower MI vicinity compared to farther north over
the U.P. of MI in closer proximity to a shortwave trough.
Nonetheless, scattered thunderstorms will gradually develop within a moist/destabilizing airmass and pose a risk for isolated strong to
perhaps locally severe/damaging gusts this afternoon.

Farther north in WI into the U.P. of MI, a weak cold front will move
into the region later this afternoon. Model guidance shows widely
scattered storms developing as filtered sunshine leads to a
destabilizing boundary layer. A few stronger thunderstorms are
possible and could yield a localized risk for marginally severe hail
and damaging gusts during the mid afternoon to early evening period.

...Southeast AZ/southwest NM...
Strong heating should result in widely scattered thunderstorms
developing near terrain-favored areas. Weak shear will result in
disorganized storms, but the development of very steep surface to
500-mb lapse rates will promote strong evaporative cooling with the
more intense downdrafts. Isolated severe gusts are possible.

..Smith/Squitieri.. 08/12/2025

$$

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ACUS01 KWNS 122002
SWODY1
SPC AC 122001

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0301 PM CDT Tue Aug 12 2025

Valid 122000Z - 131200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR PARTS OF THE
GREAT LAKES REGION...

...SUMMARY...
Strong to locally severe thunderstorms are possible over parts of
the Great Lakes/Midwest this afternoon with both damaging winds and
hail possible.

...20Z Update...
Given the weak mid/upper-level flow, the potential for organized
severe wind gusts appears very limited in southeast
Arizona/southwest New Mexico. Steep low-level lapse rates may still
support strong/gusty outflow however. Elsewhere only minor update
the general thunderstorm area were made. See the previous discussion
for additional details.

..Wendt.. 08/12/2025

.PREV DISCUSSION... /ISSUED 1128 AM CDT Tue Aug 12 2025/

...Great Lakes/Midwest...
Midday satellite/radar composite show a weakened thunderstorm band
moving east-northeast across the eastern part of Lower MI. Surface
analysis indicates rain-cooled air north of a gust front/outflow
that has become draped from southeast Lower MI into the Michiana
region. Heating south of this boundary has resulted in temperatures
warming through the mid-upper 80s with dewpoints in the lower 70s.
Additional storms will probably develop along the trailing outflow
and gradually move east-northeast with the mean wind. Considerably
weaker deep-layer shear is present across the eastern part of the
Corn Belt into the Lower MI vicinity compared to farther north over
the U.P. of MI in closer proximity to a shortwave trough.
Nonetheless, scattered thunderstorms will gradually develop within a moist/destabilizing airmass and pose a risk for isolated strong to
perhaps locally severe/damaging gusts this afternoon.

Farther north in WI into the U.P. of MI, a weak cold front will move
into the region later this afternoon. Model guidance shows widely
scattered storms developing as filtered sunshine leads to a
destabilizing boundary layer. A few stronger thunderstorms are
possible and could yield a localized risk for marginally severe hail
and damaging gusts during the mid afternoon to early evening period.

...Southeast AZ/southwest NM...
Strong heating should result in widely scattered thunderstorms
developing near terrain-favored areas. Weak shear will result in
disorganized storms, but the development of very steep surface to
500-mb lapse rates will promote strong evaporative cooling with the
more intense downdrafts. Isolated severe gusts are possible.

$$

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ACUS01 KWNS 130043
SWODY1
SPC AC 130041

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0741 PM CDT Tue Aug 12 2025

Valid 130100Z - 131200Z

...NO SEVERE THUNDERSTORM AREAS FORECAST...

...SUMMARY...
A few strong storms, with gusty winds, may linger this evening
across portions of the Midwest.

...01z Update...

Boundary-layer cooling is expected to further weaken convection
after sunset this evening. Across most of the CONUS, updraft
intensity has gradually waned over the last few hours, with only a
few robust storms lingering along a corridor from northern IN into
southeast lower MI. Lapse rates are not particularly steep across
the Midwest with roughly 6.3 C/km value noted on the DTX sounding
this evening. While parameters do not appear particularly favorable
for severe, a few robust updrafts will likely continue, partially
aided by approaching upper trough. Locally gusty winds would be the
primary concern, but overall the severe risk appears too low to
warrant MRGL Risk the rest of tonight.

..Darrow.. 08/13/2025

$$

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ACUS01 KWNS 130555
SWODY1
SPC AC 130554

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1254 AM CDT Wed Aug 13 2025

Valid 131200Z - 141200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL PLAINS...

...SUMMARY...
The evolution of an organized cluster of thunderstorms accompanied
by strong to severe wind gusts appears probable across parts of the
central Plains this evening and overnight. Scattered thunderstorms
across the Mid-Atlantic/Northeast may produce sporadic damaging
winds this afternoon.

...Synopsis...
Strong to severe thunderstorm chances today will primarily be
focused across the Mid-Atlantic/Northeast and across the central
Plains. Early-morning water-vapor imagery depicts a broad
upper-level trough across eastern Canada and Great Lakes region with
a diffuse surface front draped from the Midwest southwestward into
the Plains. This wave and its attendant surface front will spread
east through the day, reaching the Mid-Atlantic by around peak
heating when conditions should be adequately unstable for
thunderstorms. Further west, a deepening upper trough will progress
rapidly across the Pacific Northwest and northern Rockies over the
next 24 hours. Ascent ahead of this wave overspreading a dry, but
buoyant, air mass will promote scattered thunderstorms with robust
convection anticipated across the Plains later this
evening/overnight as lift impinges on a more moist/buoyant air mass.

...Central Plains...
05 UTC surface observations show modest moisture return ongoing
across the Plains in the wake of a recent frontal passage. Through
the afternoon, a deepening of the lee trough will promote stronger
moisture return just as lift ahead of the approaching wave and
high-based convection emanating off the central Rockies spreads
east. Deep, well-mixed boundary layers to the west of the surface
trough will promote strong to severe downbursts winds as well as
outflow dominant storms. Most CAM guidance suggest cold pool
consolidation will be adequate for upscale growth of at least one
convective cluster across the High Plains by mid/late evening. This
activity will likely intensify as it encounters richer moisture
within a moderately sheared environment (35-40 knots of effective
shear). This scenario appears to be the most probable based on
ensemble consensus, and hints that strong to severe winds will
likely overspread much of southern SD and northern NE through the
overnight hours. While CAMs show reasonably good agreement on the
trajectory of this system, the exact corridor of propagation remains
uncertain.

A few solutions hint at more cellular development across portions of
SD after roughly 02 UTC as isentropic ascent over an effective warm
frontal zone increases with a strengthening of the nocturnal jet.
Cells developing within the warm advection regime may evolve into
supercells with an attendant risk for large hail given strong
veering between 1-3 km and moderate effective shear. A propagating
cluster may emerge out of this regime, but ensemble support for this
scenario is comparatively weak.

...Mid-Atlantic/Northeast...
00z soundings across the region sampled rich low-level moisture as
well as poor mid-level lapse rates. However, west/southwesterly flow
aloft will advect steeper mid-level lapse rates over the next 12-18
hours. The combination of steepening lapse rates and diurnal heating
of a moist air mass should result in a modestly buoyant, but weakly
capped, environment across the Mid-Atlantic. Focused forcing along
the front coupled with limited inhibition should promote scattered
to widespread thunderstorms by 19-21 UTC. Damaging downbursts will
be possible with this activity - especially where surface
temperatures can warm into the upper 80s and low 90s. Based on
recent ensemble guidance, this appears most probable from southern
PA into the New England region. While deep-layer shear will be
fairly weak, very weak surface winds under 20-25 knot mid-level flow
may provide adequate deep-layer wind shear for a few persistent,
more robust cells and/or clusters.

..Moore/Hart.. 08/13/2025

$$

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ACUS01 KWNS 131239
SWODY1
SPC AC 131238

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0738 AM CDT Wed Aug 13 2025

Valid 131300Z - 141200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
SOUTH DAKOTA AND NORTH-CENTRAL NEBRASKA...

...SUMMARY...
Scattered severe wind gusts and isolated large hail may occur across
parts of the northern/central Plains this evening and overnight.
Thunderstorms across portions of the Northeast and Mid-Atlantic may
produce occasional damaging winds this afternoon.

...Northern/Central Plains...
The primary upper trough will remain over western/central Canada
today, with quasi-zonal westerly mid-level flow continuing over much
of the northern Rockies/Plains through the period. A
subtle/low-amplitude shortwave trough over parts of ID/western MT
this morning associated with ongoing weak convection is forecast to
advance eastward towards eastern MT/WY and the western Dakotas by
early this evening. Gradually warming low/mid-level temperatures and
a stout cap will likely hinder surface-based convective development
across much of the northern/central Plains until mid to late
afternoon at the earliest. Still, the modest large-scale ascent
associated with the approaching shortwave trough may be sufficient
in tandem with robust daytime heating and localized orographic
effects near the Black Hills to initiate thunderstorms.

Modest low-level moisture will continue to stream northward today
along/east of a surface lee trough. Initially high-based convection
across the northern/central High Plains could pose an isolated
threat for mainly severe gusts as it continues eastwards towards
greater low-level moisture and MLCAPE. The best potential for a more
focused corridor of severe winds and isolated large hail still
appears generally along/east-southeast of the Black Hills towards
central SD and perhaps north-central NE this evening into the early
overnight hours. Here, moderate instability and deep-layer shear
should overlap with a very well-mixed boundary layer, supporting a
severe wind threat with any cluster that can become established amid
a gradually strengthening low-level jet. Some uncertainty still
remains regarding this potential, however, as low/mid-level
temperatures (around 850-700 mb) are forecast to remain quite warm.

...Northeast/Mid-Atlantic...
The Northeast and portions of the Mid-Atlantic will experience the
glancing influence of upper troughing advancing eastward over
Ontario/Quebec today. A moist low-level airmass is already in place
ahead of a weak surface front extending southwestward from the Great
Lakes into the Midwest. Although lapse rates aloft will remain poor
through the afternoon, diurnal heating ahead of ongoing showers and thunderstorms this morning should promote weak to locally moderate
instability from New England to parts of the Mid-Atlantic. Generally
modest mid-level flow (around 15-25 kt at 500 mb) should tend to
limit deep-layer shear given weak winds at low levels. Even so,
loosely organized clusters may still pose some threat for isolated
damaging winds this afternoon and early evening as convection
spreads eastward amid a boundary layer characterized by steepened
low-level lapse rates.

..Gleason/Leitman.. 08/13/2025

$$

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ACUS01 KWNS 140031
SWODY1
SPC AC 140030

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 PM CDT Wed Aug 13 2025

Valid 140100Z - 141200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE CENTRAL AND NORTHERN PLAINS...

...SUMMARY...
Thunderstorms associated with severe wind gusts and hail are
expected this evening across parts of the central and northern
Plains.

...Central and Northern Plains...
A mid-level anticyclonic flow pattern is evident on water vapor
imagery over the western states, with west-northwesterly flow in
place over much of the north-central U.S. Within the flow, a subtle
shortwave trough appears to be moving through the northern High
Plains. A line of strong to severe thunderstorms is ongoing ahead of
this feature along a zone of large-scale ascent across western South
Dakota. This line will continue to move east-southeastward toward an
axis of moderate instability that is oriented from northern South
Dakota into northeastern Nebraska. The RAP has MLCAPE along this
axis in the 2000 to 3000 J/kg range. The RAP also shows a maximum in
low-level flow of 30 to 35 knots located near the instability axis,
which is contributing to moderate deep-layer shear. This is evident
on the Aberdeen, South Dakota WSR-88D VWP, which has gradually
veering winds in the low to mid-levels, and nearly 40 knots of 0-6
km shear. A similar wind profile is evident on the North Platte,
Nebraska WSR-88D VWP. In addition, RAP forecast soundings in central
South Dakota early this evening have 700-500 mb lapse rates of 8 to
9 C/km. This environment should support a continued severe threat
for a few more hours, as the line moves east-southeastward. Severe
wind gusts and hail will be the primary threats.

..Broyles.. 08/14/2025

$$

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ACUS01 KWNS 140459
SWODY1
SPC AC 140457

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1157 PM CDT Wed Aug 13 2025

Valid 141200Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Storms with large hail and severe wind gusts are expected this
afternoon and evening across parts of the central and northern
Plains, into the upper Mississippi Valley. Hailstones of greater
than 2 inches in diameter will be possible.

...Central and Northern Plains/Upper Mississippi Valley...
A series of mid-level shortwave troughs will move across the
north-central U.S. today and tonight. The first shortwave trough
will move into the upper Mississippi Valley today. Near this
feature, isolated severe storms will be possible along the eastern
edge of a moist and unstable airmass this afternoon from eastern
Minnesota southward into northern Iowa. A second shortwave trough
will move through Saskatchewan today, and into Manitoba tonight.
Ahead of the trough, a cold front will advance eastward into the
eastern Dakotas this afternoon. A moist and unstable airmass will be
in place ahead of the front. Convective initiation should take place
near or just ahead of the front as low-level convergence increases
late this afternoon or early evening. The more aggressive model
solutions suggest that storms will develop in eastern North Dakota
late this afternoon, with additional storms forming during the
evening further south into parts of South Dakota and Nebraska. A
severe threat will likely develop with some of these storms.

Model forecasts along and near the instability axis early this
evening suggest the strongest deep-layer shear will be in
northeastern North Dakota near Grand Forks. RAP forecast soundings
for this location at 00Z have MLCAPE around 3500 J/kg, with 0-6 km
shear near 45 knots, and 700-500 mb lapse rates approaching 8 C/km.
This environment will likely support supercells with large hail, and potentially hailstones greater than 2 inches in diameter with the
strongest of updrafts. A potential for severe wind gusts will also
be possible, especially if the favored storm mode transitions toward
linear during the evening. Although an isolated severe threat may
persist into the early overnight period, a capping inversion will
strengthen and result in mainly elevated storms.

Further south into southeastern North Dakota, the environment should
support severe storms during the evening, but convective initiation
is a bit less certain. Across much of South Dakota and central
Nebraska, weaker deep-layer shear will be in place, which should
help to marginalize any severe threat.

..Broyles/Moore.. 08/14/2025

$$

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ACUS01 KWNS 141236
SWODY1
SPC AC 141234

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0734 AM CDT Thu Aug 14 2025

Valid 141300Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN NORTH DAKOTA INTO NORTHWEST MINNESOTA...

...SUMMARY...
Thunderstorms capable of producing large hail and severe wind gusts
may occur this afternoon into tonight across parts of the
northern/central Plains and upper Mississippi Valley.

...Northern/Central Plains into the Upper Mississippi Valley...
Ongoing elevated thunderstorms across parts of eastern SD this
morning are occurring in association with a low-amplitude shortwave
trough and related low-level warm advection. This activity has
remained sub-severe through much of the early morning hours, but it
could still pose an isolated hail threat in the short term given
weak MUCAPE and sufficient deep-layer shear. It remains unclear
whether additional thunderstorm development will occur later this
afternoon across parts of southern MN and vicinity as the shortwave
trough continues eastward across the upper MS Valley. The airmass
across this area will gradually destabilize through the day, but
capping may tend to inhibit additional development. Still, a
conditional threat for isolated severe hail/wind exists if robust
thunderstorms can initiate, so have maintained the Marginal Risk
across southern MN for this possibility.

Thunderstorms across southern Manitoba this morning are expected to
generally remain along/north of the international border as they
continue eastward into western Ontario. A fairly strong
mid/upper-level trough will progress eastward today across Saskatchewan/Manitoba, with the southern fringe of this perturbation
glancing the northern Plains later today. Enhanced westerly
mid-level flow will overspread ND and northern MN late this
afternoon though tonight, while a surface cold front advances east-southeastward across the northern Plains through the period.
Low-level moisture will continue to stream northward ahead of the
front, with evapotranspiration also aiding surface dewpoints
potentially reaching into the upper 60s to perhaps low 70s by early
evening. Ample daytime heating and steep lapse rates aloft will aid
in the development of at least 2500-3500 J/kg of MLCAPE by late
afternoon.

The primary uncertainty regarding convective development along the
front is a capped 850-700 mb layer and weak forcing with southward
extent across the northern Plains, as the primary upper trough will
remain across Canada through the period. Even so, low-level
convergence along the front may become sufficient for cells to
initiate by early evening, mainly across parts of eastern ND into
northwest MN where MLCIN should be weakest. Any convection which can
be sustained could pose a threat for large to isolated very large
hail given a favorable thermodynamic and kinematic environment. Some
potential for upscale growth into clusters along the front remains
apparent this evening into the early overnight hours, with greater
severe wind threat. However, inhibition will quickly increase with
eastward extent across MN as nocturnal cooling of the boundary layer
occurs; so, the severe wind threat remains uncertain.

Finally, scattered high-based thunderstorms should occur this
afternoon and evening farther south across parts of the central High
Plains. As this convection spreads eastward and encounters greater
instability along/east of a surface lee trough, it may become
capable of producing isolated severe gusts and perhaps marginally
severe hail. The lack of stronger forcing aloft and modest
deep-layer shear should temper the overall severe threat with
southward extent.

..Gleason/Leitman.. 08/14/2025

$$

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ACUS01 KWNS 141630
SWODY1
SPC AC 141629

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Thu Aug 14 2025

Valid 141630Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN NORTH DAKOTA INTO NORTHWEST MINNESOTA...

...SUMMARY...
Thunderstorms capable of producing large hail and severe wind gusts
may occur this afternoon into tonight across parts of the
northern/central Plains and upper Mississippi Valley. Isolated
strong to severe gusts are also possible from the eastern Great
Basin into the central Rockies.

...Northern Plains into the Upper MS Valley...
Recent surface analysis places a low over northwest ND, along a cold
front arcing from west-central Manitoba into south-central MT. A
surface trough also extends southward from this low to another weak
low in southeast CO. Ample low-level moisture exists across the
Plains east of this surface troughing, with mid 60s dewpoints
extending up through central and eastern ND. Moist southerly
low-level flow is forecast to persist throughout the day. This
low-level moisture advection combined with evapotranspiration and
low-level convergence near the front is expected to result in upper
60s to perhaps low 70s dewpoints ahead of the front across the
eastern Dakotas by early evening. Cooling mid-level temperatures are
expected across the region, which will combine with the abundant
low-level moisture to support strong to very strong buoyancy by the
late afternoon/early evening. Recent guidance suggests MLCAPE will
range from 3000 to 4000 J/kg across the eastern Dakotas, western MN,
and central/eastern NE by 00Z Friday.

Despite this robust buoyancy, warm low to mid-level temperatures and
related capping introduce uncertainty regarding convective
initiation, particularly with southward extent. Greatest potential
for convective initiation remains across eastern ND where glancing
large-scale ascent attendant to the substantial shortwave trough
moving through Saskatchewan will augment low-level convergence along
the southeastward-progressing cold front.

Any convection which can be sustained could pose a threat for large
to isolated very large hail given a favorable thermodynamic and
kinematic environment. Given the warm and dry low to mid-levels,
strong downdrafts are possible as well. Upscale growth into clusters
along the front is possible, and some damaging gusts could occur
with these storms as well. Inhibition will quickly increase with
eastward extent across MN as nocturnal cooling of the boundary layer
occurs, limiting the eastward extent of the severe threat.

Additionally, the low-level jet will likely weaken throughout the
day but then strengthen again later this evening from western KS
into western IA. Associated warm-air advection could result in
isolated elevated convection across central MN. Most of these storms
should be sub-severe, but a few instances of hail are possible.

...Central High Plains/Central Plains...
Scattered high-based thunderstorms should develop across the central
Rockies this afternoon before the spreading eastward/southeastward
into the central High Plains. A deeply mixed boundary layer and high
cloud bases will support strong gusts with this activity as it moves
across central High Plains. As this convection spreads eastward and
encounters greater instability along/east of a surface lee trough,
it may reintensify, with the potential for
severe gusts continuing into central NE. The lack of stronger
forcing aloft and modest deep-layer shear should temper the overall
severe threat with southward extent.

...Eastern Great Basin into central Rockies...
The shortwave trough currently moving into central CA will continue eastward/southeastward throughout the day. Lift associated with this
wave will interact with the modest mid-level moisture across the
Great Basin to support scattered thunderstorm development. High
cloud bases and a deeply mixed boundary layer could support strong
downdrafts within the strongest storms, particularly across northern
UT where the best overlap between forcing, buoyancy, and modest
southwesterly flow aloft exists.

..Mosier/Squitieri.. 08/14/2025

$$

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ACUS01 KWNS 141959
SWODY1
SPC AC 141957

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Thu Aug 14 2025

Valid 142000Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
EASTERN NORTH DAKOTA...NORTHWEST MINNESOTA...AND FAR NORTHEAST SOUTH
DAKOTA...

...SUMMARY...
Thunderstorms capable of producing large hail and severe wind gusts
may occur this afternoon into tonight across parts of the
northern/central Plains and upper Mississippi Valley. Isolated
strong to severe gusts are also possible from the eastern Great
Basin into the central Rockies.

...20Z Update...
The forecast remains on track, and only minor changes were made with
this update. Isolated to widely scattered thunderstorms are still
expected along the cold front as it impinges on a destabilizing air
mass across the northern Plains/Upper MS Valley tonight. Large hail
and locally severe gusts will be possible with any organized clusters/supercells that evolve. Elsewhere, see MCDs 1944 and 1945
for details on the near-term severe risks in the Great Basin/central
Rockies and Upper Midwest.

..Weinman.. 08/14/2025

.PREV DISCUSSION... /ISSUED 1129 AM CDT Thu Aug 14 2025/

...Northern Plains into the Upper MS Valley...
Recent surface analysis places a low over northwest ND, along a cold
front arcing from west-central Manitoba into south-central MT. A
surface trough also extends southward from this low to another weak
low in southeast CO. Ample low-level moisture exists across the
Plains east of this surface troughing, with mid 60s dewpoints
extending up through central and eastern ND. Moist southerly
low-level flow is forecast to persist throughout the day. This
low-level moisture advection combined with evapotranspiration and
low-level convergence near the front is expected to result in upper
60s to perhaps low 70s dewpoints ahead of the front across the
eastern Dakotas by early evening. Cooling mid-level temperatures are
expected across the region, which will combine with the abundant
low-level moisture to support strong to very strong buoyancy by the
late afternoon/early evening. Recent guidance suggests MLCAPE will
range from 3000 to 4000 J/kg across the eastern Dakotas, western MN,
and central/eastern NE by 00Z Friday.

Despite this robust buoyancy, warm low to mid-level temperatures and
related capping introduce uncertainty regarding convective
initiation, particularly with southward extent. Greatest potential
for convective initiation remains across eastern ND where glancing
large-scale ascent attendant to the substantial shortwave trough
moving through Saskatchewan will augment low-level convergence along
the southeastward-progressing cold front.

Any convection which can be sustained could pose a threat for large
to isolated very large hail given a favorable thermodynamic and
kinematic environment. Given the warm and dry low to mid-levels,
strong downdrafts are possible as well. Upscale growth into clusters
along the front is possible, and some damaging gusts could occur
with these storms as well. Inhibition will quickly increase with
eastward extent across MN as nocturnal cooling of the boundary layer
occurs, limiting the eastward extent of the severe threat.

Additionally, the low-level jet will likely weaken throughout the
day but then strengthen again later this evening from western KS
into western IA. Associated warm-air advection could result in
isolated elevated convection across central MN. Most of these storms
should be sub-severe, but a few instances of hail are possible.

...Central High Plains/Central Plains...
Scattered high-based thunderstorms should develop across the central
Rockies this afternoon before the spreading eastward/southeastward
into the central High Plains. A deeply mixed boundary layer and high
cloud bases will support strong gusts with this activity as it moves
across central High Plains. As this convection spreads eastward and
encounters greater instability along/east of a surface lee trough,
it may reintensify, with the potential for
severe gusts continuing into central NE. The lack of stronger
forcing aloft and modest deep-layer shear should temper the overall
severe threat with southward extent.

...Eastern Great Basin into central Rockies...
The shortwave trough currently moving into central CA will continue eastward/southeastward throughout the day. Lift associated with this
wave will interact with the modest mid-level moisture across the
Great Basin to support scattered thunderstorm development. High
cloud bases and a deeply mixed boundary layer could support strong
downdrafts within the strongest storms, particularly across northern
UT where the best overlap between forcing, buoyancy, and modest
southwesterly flow aloft exists.

$$

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ACUS01 KWNS 150036
SWODY1
SPC AC 150035

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0735 PM CDT Thu Aug 14 2025

Valid 150100Z - 151200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Thunderstorms capable of producing large hail and severe wind gusts
may occur tonight across parts of the northern Plains and upper
Mississippi Valley.

...Northern Plains/Upper MS Valley...

Low-amplitude short-wave trough is currently noted across southeast SK/northeast MT, shifting east in line with latest model guidance.
This feature is forecast to shift across western MB by 15/06z, with
the southern influence of weak height falls expected into the upper
Red River Region later tonight. Scattered thunderstorms have
developed ahead of this feature across southeast MB/northwest ON,
but trailing convection along the front south of the border is
weak/shallow. Even so, with time isolated-scattered thunderstorms
are expected to develop. 00z sounding from ABR exhibited substantial
capping near 800mb, but MLCAPE was appreciable with ~3500 J/kg.
Additionally, 0-6km shear was also strong, and more than adequate
for supercells. Frontal ascent will likely aid convection later this
evening, and earlier thoughts regarding the evolution of severe
remain.

..Darrow.. 08/15/2025

$$

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ACUS01 KWNS 150534
SWODY1
SPC AC 150532

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1232 AM CDT Fri Aug 15 2025

Valid 151200Z - 161200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY...

...SUMMARY...
Scattered severe storms are likely over parts of the northern Plains
and Upper Mississippi Valley.

...Northern Plains/Upper MS Valley...

Broad anticyclonic flow is forecast to continue across the
central/southern Plains during the day1 period. Stronger 500mb flow
will extend around the periphery of this feature, extending from the
northern Rockies-northern Plains-upper Great Lakes. While a few
disturbances will eject across the northern Rockies toward the upper
MS Valley, latest model guidance suggests heights will actually rise
much of the period. One such feature currently extends from eastern
WY into northeast CO. Scattered thunderstorms are noted immediately
downstream from the Black Hills into western NE. This disturbance
should advance into central SD by the start of the period, then into
MN by early afternoon. While a few strong storms may be ongoing at
the start of the period, renewed development is expected during the
afternoon across the upper MS Valley. LLJ is forecast to increase a
bit into southwest MN ahead of the short wave, and this should
encourage robust convection along a front that will be draped from
southwest MN-northern WI. Strong buoyancy will be noted south of the
front across much of this region and MLCAPE could exceed 3000 J/kg
from MN/IA into SD/NE. While the short wave should encourage
organized convection, boundary-layer heating will prove instrumental
in thunderstorm development. Forecast soundings suggest CINH weakens considerably by 19-21z and convection should expand in areal
coverage as convective temperatures are breached. Wind/hail are the
primary risks, though a brief tornado can not be ruled out with any
supercell structures.

Farther west, convective temperatures will be breached across
eastern WY by 22z. Scattered storms will once again develop over the
higher terrain/Plains then spread downstream into western
SD/northwestern NE during the evening. Some consideration was given
to a SLGT risk for this activity but the short-wave trough that
should affect this region will eject across northern AZ into
southwest WY around 16/00z. Timing of this feature suggests stronger
support will not affect this region until well after sunset.

..Darrow/Lyons.. 08/15/2025

$$

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ACUS01 KWNS 151234
SWODY1
SPC AC 151233

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0733 AM CDT Fri Aug 15 2025

Valid 151300Z - 161200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT FROM PARTS OF SOUTH DAKOTA INTO THE UPPER MIDWEST...

...SUMMARY...
Scattered strong to severe storms are likely today and tonight over
parts of the northern Plains and Upper Mississippi Valley.

...MN/IA/WI...
Latest water vapor loop shows a convectively-aided shortwave trough
moving across SD/NE. A cluster of intense thunderstorms has tracked
across central/eastern SD overnight producing occasional wind damage
(reference MCD #1949). Another small cluster of storms is over
northeast NE. Both of these areas of convection are moving into a
moist and potentially moderately unstable air mass, although they
may take a few hours of heating to intensify further. Despite
short-term uncertainty, a consensus of overnight CAM guidance
depicts storms intensifying by early afternoon and tracking eastward
across parts of MN, northeast IA, and western WI. Locally damaging
wind gusts and hail will be possible. Have expanded the SLGT risk
area slightly farther south in line with recent model solutions.

...SD/NE this afternoon/tonight...
Strong heating and ample mid-level moisture will result in scattered
high-based thunderstorm development across eastern WY and western
NE/SD by late afternoon. This activity will track
east-northeastward through the early evening into a progressively
more moist and unstable air mass. The combination of improving
thermodynamic environment and an intensifying nocturnal low-level
jet will likely aid in thunderstorm intensification through the
evening across northern NE and central SD. Damaging winds and hail
will be possible. Recent HRRR/RRFS runs suggest an
upscale-organizing MCS could occur after midnight, tracking into
western MN. Have extended the SLGT westward to account for this
scenario.

..Hart/Dean.. 08/15/2025

$$

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ACUS01 KWNS 151632
SWODY1
SPC AC 151630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Fri Aug 15 2025

Valid 151630Z - 161200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT FROM PARTS OF SOUTH DAKOTA INTO THE UPPER MIDWEST...

...SUMMARY...
Scattered strong to severe storms are likely today and tonight over
parts of the northern Plains and Upper Mississippi Valley.

...MN/IA/WI...
Recent satellite imagery shows a pair of convectively generated
vorticity maxima moving across the northern/central Plains, with the northernmost vorticity max over the eastern ND/SD border and the
southernmost vorticity max over north-central NE. Showers and
thunderstorms have persisted near these features over the last
several hours, but the strongest cells in both of these clusters
have recently shown a weakening trend. A moist and buoyant airmass, characterized by dewpoints in the upper 60s/low 70s, exists
downstream and redevelopment is possible ahead of both of these
vorticity maxima. How that redevelopment evolves is uncertain, with
recent guidance offering varied solutions regarding overall coverage
and evolution.

Redevelopment appears most probable with the southern vorticity
maxima, given the ample moist and buoyancy that exists downstream.
This development should grow upscale quickly, with the resulting
convective cluster then tracking southeastward. Recent guidance
continues to trend farther south, so the wind probabilities were
extended southward to cover this potential. Damaging gusts appear
like the most likely threat through the evening. Current progression
of the northern vorticity maximum takes it into a less buoyant
airmass across central MN and northern WI, and redevelopment
along/ahead of this disturbance appears less likely.

Depending on the strength of the IA cluster, additional development
is possible in its wake amid a strengthening low-level jet and
associated warm-air advection over its outflow. Steep mid-level
lapse rates should still be in place, supporting strong updrafts and
large hail with these elevated storms.

Lastly, a decaying convective line may reach the southwestern
MN/northwestern IA vicinity late in the period. Given the potential
for preceding storms, the amount of buoyancy that will still be in
place remains is uncertain. However, if thunderstorm coverage is low
or most storms develop farther east, enough buoyancy could remain to
support strong updrafts capable of damaging gusts and/or hail within
the convective line or any preceding more cellular storms.

..NE/SD this afternoon through tonight...
Strong heating and ample mid-level moisture will result in scattered
high-based thunderstorm development across eastern WY and western
NE/SD by late afternoon. Isolated hail and strong gusts are possible
with this initial activity. This activity will then track
east-northeastward through the early evening into a progressively
more moist and unstable air mass across NE and SD. The combination
of improving thermodynamic environment and an intensifying nocturnal
low-level jet will likely aid in thunderstorm intensification and
upscale growth through the evening across northern NE and central
SD. Guidance continues to vary significantly with the strength of
this MCS, but general consensus would suggest the threat for strong
to severe gusts will persist across SD tonight. There is at least a
low probability for the development of a well-organized MCS that
could produce significant severe gusts. However, that probability is
currently too low to introduce an unconditional sig wind area.

...TX Coastal Plain into the Hill Country and Southeast TX...
A maturing tropical disturbance is near south TX, with associated
outflow currently spreading northward across the TX Coastal Plain.
Limited lightning has been noted with in the short-lived cores that
have been developing along this outflow. This process of brief
intensification along this outflow is expected throughout the day,
with an overall increase in thunderstorm coverage anticipated. A
modest increase in low to mid-level flow is expected along the
eastern periphery of this system, spreading northward into central
and southeast TX. Even so, shear will remain weak, with a
disorganized multicellular pulse storm mode anticipated. Given the
very moist profiles (i.e. PW values over 2"), a few water-loaded
downbursts are possible, but should be isolated enough to preclude
the need for severe probabilities.

..Mosier/Wendt.. 08/15/2025

$$

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ACUS01 KWNS 151958
SWODY1
SPC AC 151957

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Fri Aug 15 2025

Valid 152000Z - 161200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THOUGH TONIGHT
FROM THE UPPER MISSISSIPPI VALLEY INTO SOUTH DAKOTA...

...SUMMARY...
Scattered strong to severe storms with damaging winds and large hail
are likely through tonight from the Upper Mississippi Valley into
South Dakota.

...Upper MS Valley through tonight...
Convection is ongoing in a cluster across north central IA, with
clear evidence of cold pool development and a bowing structure. The
storms will likely continue to spread eastward/southeastward through
the afternoon while encountering a very unstable environment
characterized by surface temperatures in the upper 80s and
boundary-layer dewpoints in the low-mid 70s. Cluster is expected to
be maintained given deep-layer shear vectors near 30 kt (oriented west-northwest to east-southeast), and steep midlevel lapse rates
will support the potential for occasional damaging/severe outflow
gusts and isolated large hail with the strongest embedded updrafts.

Otherwise, a strengthening low-level warm advection regime will
develop tonight into MN along a slow-moving front, and atop the cold
pool from the ongoing IA storms. Elevated buoyancy will remain
large, with the potential to support additional severe storm
development with occasional large hail and damaging/severe outflow
gusts.

...NE/SD this evening into tonight...
High-based convection is expected to form this afternoon from
southeast WY into the western NE Panhandle and southwest SD. The
initial storms will be capable of producing a few severe outflow
gusts in an environment with deep inverted-V profiles and modest
buoyancy. Though surface convective inhibition will increase this
evening with diurnal cooling, storms could grow into a cluster
through outflow interactions, while moving into richer low-level
moisture and larger buoyancy with eastward extent (along and south
of a baroclinic zone across SD).

..Thompson.. 08/15/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Fri Aug 15 2025/

...MN/IA/WI...
Recent satellite imagery shows a pair of convectively generated
vorticity maxima moving across the northern/central Plains, with the northernmost vorticity max over the eastern ND/SD border and the
southernmost vorticity max over north-central NE. Showers and
thunderstorms have persisted near these features over the last
several hours, but the strongest cells in both of these clusters
have recently shown a weakening trend. A moist and buoyant airmass, characterized by dewpoints in the upper 60s/low 70s, exists
downstream and redevelopment is possible ahead of both of these
vorticity maxima. How that redevelopment evolves is uncertain, with
recent guidance offering varied solutions regarding overall coverage
and evolution.

Redevelopment appears most probable with the southern vorticity
maxima, given the ample moist and buoyancy that exists downstream.
This development should grow upscale quickly, with the resulting
convective cluster then tracking southeastward. Recent guidance
continues to trend farther south, so the wind probabilities were
extended southward to cover this potential. Damaging gusts appear
like the most likely threat through the evening. Current progression
of the northern vorticity maximum takes it into a less buoyant
airmass across central MN and northern WI, and redevelopment
along/ahead of this disturbance appears less likely.

Depending on the strength of the IA cluster, additional development
is possible in its wake amid a strengthening low-level jet and
associated warm-air advection over its outflow. Steep mid-level
lapse rates should still be in place, supporting strong updrafts and
large hail with these elevated storms.

Lastly, a decaying convective line may reach the southwestern
MN/northwestern IA vicinity late in the period. Given the potential
for preceding storms, the amount of buoyancy that will still be in
place remains is uncertain. However, if thunderstorm coverage is low
or most storms develop farther east, enough buoyancy could remain to
support strong updrafts capable of damaging gusts and/or hail within
the convective line or any preceding more cellular storms.

..NE/SD this afternoon through tonight...
Strong heating and ample mid-level moisture will result in scattered
high-based thunderstorm development across eastern WY and western
NE/SD by late afternoon. Isolated hail and strong gusts are possible
with this initial activity. This activity will then track
east-northeastward through the early evening into a progressively
more moist and unstable air mass across NE and SD. The combination
of improving thermodynamic environment and an intensifying nocturnal
low-level jet will likely aid in thunderstorm intensification and
upscale growth through the evening across northern NE and central
SD. Guidance continues to vary significantly with the strength of
this MCS, but general consensus would suggest the threat for strong
to severe gusts will persist across SD tonight. There is at least a
low probability for the development of a well-organized MCS that
could produce significant severe gusts. However, that probability is
currently too low to introduce an unconditional sig wind area.

...TX Coastal Plain into the Hill Country and Southeast TX...
A maturing tropical disturbance is near south TX, with associated
outflow currently spreading northward across the TX Coastal Plain.
Limited lightning has been noted with in the short-lived cores that
have been developing along this outflow. This process of brief
intensification along this outflow is expected throughout the day,
with an overall increase in thunderstorm coverage anticipated. A
modest increase in low to mid-level flow is expected along the
eastern periphery of this system, spreading northward into central
and southeast TX. Even so, shear will remain weak, with a
disorganized multicellular pulse storm mode anticipated. Given the
very moist profiles (i.e. PW values over 2"), a few water-loaded
downbursts are possible, but should be isolated enough to preclude
the need for severe probabilities.

$$

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ACUS01 KWNS 160100
SWODY1
SPC AC 160059

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0759 PM CDT Fri Aug 15 2025

Valid 160100Z - 161200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO
THE OVERNIGHT HOURS ACROSS PARTS OF CENTRAL AND EASTERN SOUTH
DAKOTA...NORTHERN NEBRASKA...SOUTHWESTERN MINNESOTA...NORTHWESTERN
IOWA...PARTS OF SOUTHEASTERN IOWA AND SOUTHWESTERN WISCONSIN...

...SUMMARY...
An organizing cluster of thunderstorms with potential to produce
strong to severe wind gusts may still evolve later this evening into
the overnight hours across parts of the middle Missouri Valley and
adjacent Great Plains.

...01Z Update...
Stronger westerlies remain generally confined to the higher
latitudes, near/north of the Canadian/U.S. border. To the southwest
of one significant embedded short wave trough crossing the Hudson
Bay and northern Ontario vicinity, modest westerly mid-level flow
(including speeds of 30-40 kt around 500 mb) is overspreading areas
as far south as the Dakotas into Upper Midwest, near the northern
periphery of mid-level ridging. Forcing associated with subtle
perturbations embedded within this regime has contributed to several
developing clusters of storms. A couple now propagating east of
the upper Mississippi Valley appear to be in the process of
weakening, likely due to some combination of weak/weakening lift and
increasing inhibition beneath relatively warm mid-level temperatures encompassing much of the northern and central Great Plains into
Midwest.

Beneath steeper mid-level lapse rates upstream, boundary-layer
moisture east of the lee surface trough across the high plains is
still contributing to strong to extreme potential instability across
much of central and eastern South Dakota/Nebraska, as scattered high
based convection emerges from eastern Wyoming and northeastern
Colorado. It appears possible that low-level forcing for ascent,
near the nose of a nocturnally strengthening southerly low-level
jet, could contribute to a consolidating and upscale growing
cluster, particularly as activity acquires more unstable inflow
later this evening into the overnight. Various model output,
including the NAM and Rapid Refresh, suggest that the evolution of a
notable convective perturbation is possible, which could be
accompanied by a swath of strong to severe wind gusts.

..Kerr.. 08/16/2025

$$

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ACUS01 KWNS 160601
SWODY1
SPC AC 160600

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0100 AM CDT Sat Aug 16 2025

Valid 161200Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON INTO TONIGHT ACROSS SOUTH DAKOTA AND PERHAPS ADJACENT
PORTIONS OF NORTHERN NEBRASKA...NORTHEASTERN WYOMING...SOUTHEASTERN MONTANA...AND SOUTHWESTERN NORTH DAKOTA...

...SUMMARY...
Scattered strong thunderstorm development, including a couple of
evolving clusters posing a risk for strong to severe wind gusts, are
possible today into tonight across parts of the northern Great
Plains into Midwest and Great Lakes region.

...Discussion...
Stronger westerlies in the northern mid-latitudes are forecast to
generally remain confined to the north of the Canadian/U.S. border.
Within this regime, mid-level ridging, now building across and
northeast of the Canadian and adjacent northern U.S. Rockies, is
likely to undergo further amplification across and east of the
Canadian Prairies later today through tonight, downstream of an
initially vigorous short wave trough pivoting northeastward inland
of the British Columbia coast.

Models indicate that larger-scale troughing across the northeastern
Pacific will be maintained, as another vigorous short wave trough
digs southeast of the Gulf of Alaska. Downstream of the building
ridge, large-scale eastern Canadian mid-level troughing is forecast
to undergo amplification, as another notable short wave trough digs
across and southeast/east of the northern Ontario/southern Hudson
and James Bay vicinities. Even as this occurs, it appears that
modest mid-level height rises will develop across eastern portions
of the northern U.S. Great Plains through the Upper Midwest and
adjacent Great Lakes region later today through tonight, downstream
of mid-level troughing within weak, broadly confluent mid-level flow
across the Wyoming/Colorado Rockies into the western Dakotas. The
remnants of an initially notable convectively generated or enhanced perturbation may dig southeastward within the northeastern periphery
of the building ridging, across the Midwest/adjacent Great Lakes
vicinity into Ohio Valley. However, there is considerably greater
spread evident in model output concerning this feature.

...Northern Great Plains into Great Lakes/Ohio Valley...
South of the westerlies, convective potential may depend largely on sub-synoptic developments with still relatively low predictability.
The NAM and Rapid Refresh, among other model output, continue to
suggest a notable perturbation evolving with a consolidating cluster
of storms now across parts of central South Dakota into north
central Nebraska. By 12Z this morning, it appears that this may be
in the process of spreading east of the mid Missouri through upper
Mississippi Valleys, above a boundary-layer stabilized by preceding
convective activity.

A conglomerate surface outflow boundary currently extends from parts
of central Illinois through central Iowa and Minnesota. It seems
probable that the southern flank of this boundary will undergo at
least some modification/northward return into and beyond daybreak,
but the extent remains unclear. Outflow impacted air across eastern
Minnesota and northeastern Iowa into Wisconsin will probably be
reinforced by the approaching cluster, which probably will tend to
weaken while overspreading the Upper Midwest into Great Lakes
region. However, depending on how quickly the boundary-layer is
able to modify on the trailing flank of the reinforced outflow, it
appears possible that renewed thunderstorm development and
intensification could occur, and eventually grow upscale into
another organizing cluster with a tendency to propagate
southeastward toward the Ohio Valley.

HREF output suggests that a corridor across southern Wisconsin
toward areas near and south of southern Lake Michigan may need to be
considered for higher severe probabilities in later outlooks for
this period. However, given uncertain boundary-layer
destabilization, coupled with a tendency for warming aloft/rising
mid-level heights, in the presence of generally weak ambient mean
flow, there seems a reasonable possibility that the corridor of
higher convective potential evident in the HREF may be displaced, if
not overdone.

Otherwise, there remains a signal in model output that the
approaching mid-level troughing could contribute to another upscale
growing cluster of storms with potential to produce strong to severe
wind gusts across parts of South Dakota this evening. However, this
signal is more tempered than prior days.

..Kerr/Lyons.. 08/16/2025

$$

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ACUS01 KWNS 161222
SWODY1
SPC AC 161221

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0721 AM CDT Sat Aug 16 2025

Valid 161300Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON AND
TONIGHT OVER PARTS OF SOUTH DAKOTA...

...SUMMARY...
Scattered strong/severe thunderstorms are possible today into
tonight across parts of the northern Great Plains into Midwest and
Great Lakes region.

...MN/Great Lakes Region...
A long-lived severe MCS that affected parts of SD and southwest MN
overnight has weakened in east-central MN. These storms will track
eastward this morning into a region of moderate MUCAPE, but slightly cooler/drier surface air over WI that was affected by one or more
areas of thunderstorms yesterday. For this reason, these storms are
expected to struggle to organize, with locally gusty winds being the
main concern today. Refer to MCD #1963 for further short-term
details.

Farther south across parts of IA/IL/IN, an overnight MCS pushed the
effective surface boundary south into northeast MO and central IL.
Strong daytime heating and southerly low-level winds will help the
boundary to retreat back into northern IA/IL by mid-afternoon. The
corridor along/north of the boundary should provide the greatest
potential for re-development of a few storms later today, with
locally damaging wind gusts possible. Given the uncertainty of
where the boundary is, and anticipated limited coverage of storms,
will maintain MRGL risk at this time.

...SD and Vicinity...
A well-defined but rather weak shortwave trough is currently over
western CO and will spread into eastern WY/western Dakotas by
evening. Similar to yesterday, high-based storms will develop ahead
of the approaching trough and intensify as they move eastward into a progressively more moist/unstable air mass over west-central SD.
Another nocturnal MCS may affect central/eastern SD tonight, with a
risk of damaging wind gusts and some hail.

..Hart/Dean.. 08/16/2025

$$

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ACUS01 KWNS 161631
SWODY1
SPC AC 161630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Sat Aug 16 2025

Valid 161630Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND
TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER
SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL...

...SUMMARY...
Scattered strong/severe thunderstorms are possible today into
tonight across parts of the northern Great Plains into Midwest and
Great Lakes region.

...Upper Midwest into the Mid MS Valley and Upper Great Lakes
Region...
An expansive MCS continues to move eastward across the Upper
Midwest, with a well-defined MCV evident in radar imagery over the
central WI/MN border vicinity. This MCS has continued to gradually
weaken throughout the morning, but a few strong updrafts persist
along its southeastern periphery over central WI. This portion of
the MCS is on the far northeastern periphery of the plume of steeper
mid-level lapse rates that extends from the northern/central High
Plains across the central Plains and into the Mid MS Valley. This
plume is observable in the 12Z sounding from DVN and ILX, which
sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km,
respectively. Dewpoints downstream across southern WI, northern IL,
and northern IN are in the low 70s, with upper 60s dewpoints also
covering much of southern Lower MI. The combination of ample
low-level moisture and steep mid-level lapse rates will result in
strong to very strong buoyancy to the south of the MCS from the
MN/IA border into northern/central IL.

Given the lack of a well-defined surface boundary and negligible
large-scale ascent, additional thunderstorm development will be
associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample
moisture and buoyancy downstream of the leading edge of the MCS
suggests the greater severe potential this afternoon/evening will
likely be associated with redevelopment/reintensification of the
MCS. Additionally, even if reintensification does not occur along
the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern
periphery of the MCV circulation as it moves into northern/central
WI. Increased severe-wind probabilities (i.e. 15%) were introduced
with this outlook to cover both of these potential scenarios. A
small 15% hail probability was introduce to cover potential for
later evening storms atop the outflow as well.

Storms are possible into northern IN and the Lower MI this afternoon
and evening as well, but the lower buoyancy should temper the
overall coverage and magnitude in these areas.

...SD and Vicinity...
A well-defined but rather weak shortwave trough is currently moving
through western CO/western WY, and will continue northeastward into
eastern WY/western Dakotas by this evening. Similar to yesterday,
high-based storms will develop ahead of the approaching shortwave
and intensify as they move eastward into a progressively more
moist/unstable air mass over west-central SD. Upscale growth into
another nocturnal MCS is forecast by most guidance, with the MCS
tracking northeastward across western/central SD tonight. Strong to
severe gusts are possible with this potential MCS across much of western/central SD.

..Mosier/Wendt.. 08/16/2025

$$

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ACUS01 KWNS 161958
SWODY1
SPC AC 161957

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0257 PM CDT Sat Aug 16 2025

Valid 162000Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING AND
TONIGHT OVER PART OF SD...AND THIS AFTERNOON THROUGH TONIGHT OVER
SOUTHEAST MN...SOUTHERN WI...AND NORTHERN IL...

...SUMMARY...
Scattered strong/severe thunderstorms are possible today into
tonight across parts of the northern Great Plains into the Midwest
and Great Lakes regions.

...20Z Update...
The prior forecast reasoning remains valid. Severe probabilities
were reduced in parts of northern/central Wisconsin where prior
convection has stabilized the boundary layer. Elsewhere, only minor
changes were made to the general thunderstorm forecast based on
current observational trends. See the previous discussion as well as
MCDs 1965/1966 for additional information.

..Wendt.. 08/16/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sat Aug 16 2025/

...Upper Midwest into the Mid MS Valley and Upper Great Lakes
Region...
An expansive MCS continues to move eastward across the Upper
Midwest, with a well-defined MCV evident in radar imagery over the
central WI/MN border vicinity. This MCS has continued to gradually
weaken throughout the morning, but a few strong updrafts persist
along its southeastern periphery over central WI. This portion of
the MCS is on the far northeastern periphery of the plume of steeper
mid-level lapse rates that extends from the northern/central High
Plains across the central Plains and into the Mid MS Valley. This
plume is observable in the 12Z sounding from DVN and ILX, which
sampled 700-500 mb lapse rates of 7.8 and 7.2 deg C per km,
respectively. Dewpoints downstream across southern WI, northern IL,
and northern IN are in the low 70s, with upper 60s dewpoints also
covering much of southern Lower MI. The combination of ample
low-level moisture and steep mid-level lapse rates will result in
strong to very strong buoyancy to the south of the MCS from the
MN/IA border into northern/central IL.

Given the lack of a well-defined surface boundary and negligible
large-scale ascent, additional thunderstorm development will be
associated with outflow from with the MCS, which results in greater-than-average uncertainty for the Day 1 period. Ample
moisture and buoyancy downstream of the leading edge of the MCS
suggests the greater severe potential this afternoon/evening will
likely be associated with redevelopment/reintensification of the
MCS. Additionally, even if reintensification does not occur along
the leading edge of the MCS this afternoon, most guidance suggests redevelopment does eventually occur this evening along the southern
periphery of the MCV circulation as it moves into northern/central
WI. Increased severe-wind probabilities (i.e. 15%) were introduced
with this outlook to cover both of these potential scenarios. A
small 15% hail probability was introduce to cover potential for
later evening storms atop the outflow as well.

Storms are possible into northern IN and the Lower MI this afternoon
and evening as well, but the lower buoyancy should temper the
overall coverage and magnitude in these areas.

...SD and Vicinity...
A well-defined but rather weak shortwave trough is currently moving
through western CO/western WY, and will continue northeastward into
eastern WY/western Dakotas by this evening. Similar to yesterday,
high-based storms will develop ahead of the approaching shortwave
and intensify as they move eastward into a progressively more
moist/unstable air mass over west-central SD. Upscale growth into
another nocturnal MCS is forecast by most guidance, with the MCS
tracking northeastward across western/central SD tonight. Strong to
severe gusts are possible with this potential MCS across much of western/central SD.

$$

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ACUS01 KWNS 170051
SWODY1
SPC AC 170050

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0750 PM CDT Sat Aug 16 2025

Valid 170100Z - 171200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
NORTHERN AND CENTRAL SOUTH DAKOTA AND SOUTHERN NORTH DAKOTA...

...SUMMARY...
A small organized cluster of thunderstorms with potential to produce
a swath of strong to severe wind gusts still appears possible across
parts of the central Dakotas later this evening into the overnight
hours. More sporadic strong thunderstorms with potential to produce
severe wind and hail are possible in a corridor across the Midwest
into Great Lakes vicinity.

...01Z Update...
In the wake of a weakening convective perturbation shifting
east-southeastward through the Great Lakes region, modest mid-level
height rises across eastern portions of the northern Great Plains
will gradually overspread the Upper Midwest and adjacent Great Lakes
region overnight. In the presence of weak and/or weakening
deep-layer shear, and weak mid/upper support for convective
development, the probabilities for the evolution of a sustained
organized severe storm cluster appear to be lowering. However, weak
low-level warm advection to the immediate cool side of convective
outflow, and a quasi-stationary frontal zone extending roughly from west-northwest of the Dubuque IA vicinity into the middle Missouri
Valley, is forecast to contribute to a corridor of increasing
thunderstorm development overnight. Although mid-level profiles
appear relatively warm, a plume of dry lower/mid-tropospheric air
with steep lapse rates may contribute to a risk for localized strong
wind gusts and some hail in sporadic stronger storms.

Upstream, across the middle Missouri Valley, as a weak mid-level
short wave trough slowly shifts eastward into the western Dakotas,
models continue to suggest that associated scattered thunderstorm
development may gradually consolidate into an organizing cluster,
perhaps aided by lift associated with warm advection on the nose of
a strengthening southerly low-level jet. As this occurs, although
deep-layer mean wind fields will remain generally weak, modest shear
and thermodynamic profiles with steep lower/mid-tropospheric lapse
rates and sizable CAPE may contribute to potential for the
development of strong to severe wind gusts overnight.

..Kerr.. 08/17/2025

$$

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ACUS01 KWNS 170550
SWODY1
SPC AC 170548

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1248 AM CDT Sun Aug 17 2025

Valid 171200Z - 181200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE THIS
AFTERNOON INTO TONIGHT ACROSS PARTS OF THE NORTHERN
ROCKIES...PORTIONS OF THE MIDDLE MISSOURI VALLEY AND ADJACENT GREAT PLAINS...AND PARTS OF THE NORTHERN MID ATLANTIC...

...SUMMARY...
One or two clusters of thunderstorms may develop and gradually pose
a risk for strong to severe wind gusts across parts of the northern
Rockies into middle Missouri Valley late today into tonight. Strong thunderstorm development accompanied by potentially damaging wind
gusts is also possible across parts of the northern Mid Atlantic
late this afternoon and evening.

...Discussion...
Large-scale mid-level troughing is forecast to undergo further
amplification across southeastern Quebec through portions of
northern New England and the Canadian Maritimes during this period.
As this occurs, a notable cold front is forecast to advance
southward across much of the Northeast, Mid Atlantic and Ohio Valley
by 12Z Monday, beneath the northeastern periphery of large-scale
mid/upper ridging encompassing much of the interior U.S and southern
Canadian Provinces.

The western flank of the intrusion of cooler/drier boundary layer
air is likely to stall across the lower Ohio Valley into Upper
Midwest vicinity, but a more modest southward cool surge is also
forecast across the northern high plains, in the wake of weak
mid-level troughing slowly migrating within the larger-scale ridging
across and east of the Dakotas/Nebraska vicinity.

A number of other smaller-scale perturbations are forecast to
progress through modest/weak cyclonic to anticyclonic flow inland of
the Pacific coast through the Rockies, downstream of a significant,
amplifying large-scale trough offshore of the British Columbia and
Pacific Northwest coast.

...Parts of the mid Missouri Valley into Midwest...
Models indicate unsaturated lower/mid-tropospheric thermodynamic
profiles with steep lapse rates, aided by continuing eastward
advection of elevated mixed-layer air, will be maintained across
much of the South Dakota and Nebraska vicinity through this period.
Beneath this regime, seasonably high boundary-layer moisture content
will continue to contribute to the development of moderate to large
potential instability with insolation, along and south of an
initially stalled frontal zone across southern Minnesota/southern
Iowa through southern South Dakota.

Residual convection with a possible MCV may be in the process of
spreading well to the cool side of this boundary, across and
northeast of the eastern Dakotas at 12Z this morning. There appears
at least some potential for renewed convective development along the
southern flank of this activity, in closer proximity to the frontal
zone and destabilizing boundary-layer (roughly focused near the
Minnesota/Iowa border), aided by forcing for ascent associated with
warm advection during the day. Otherwise, stronger thunderstorm
development may await forcing associated with a perturbation within
the southern periphery of the weak mid-level troughing forecast to
overspread the (roughly) South Dakota/Nebraska border vicinity by
early this evening.

There is considerable spread evident among the models concerning
these and subsequent developments, with the NAM depicting the
evolution of a notable convective perturbation. Other output is
less pronounced, but, despite generally weak wind fields and shear,
forecast thermodynamic profiles appear potentially conducive to the
evolution of an upscale growing and organizing cluster with the
potential to produce strong to severe wind gusts this evening and
overnight.

...Montana...
Downstream of the northeastern Pacific mid-level trough, at least
broadly difluent upper flow, perhaps enhanced ahead of a subtle
mid-level wave crossing the northern Rockies, may aid the
development of thunderstorm activity off the mountains of south
central into southeastern Montana late this afternoon and evening.
Forecast soundings east of the higher terrain appear to include
sufficient shear and favorable thermodynamic profiles for the
evolution of a small east-southeastward propagating cluster with
potential to produce severe wind and hail.

...Northern Mid Atlantic...
Seasonably high moisture content and boundary-layer heating focused
along a pre-frontal surface trough may contribute to an environment
conducive to a few strong downbursts, aided by heavy precipitation
loading. It is possible that forcing for ascent associated with a
remnant convectively generated perturbation may contribute to a
clustering of thunderstorm activity along this corridor, from parts
of northern Virginia through southeastern Pennsylvania and New
Jersey, late this afternoon or evening.

..Kerr/Lyons.. 08/17/2025

$$

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ACUS01 KWNS 171221
SWODY1
SPC AC 171220

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0720 AM CDT Sun Aug 17 2025

Valid 171300Z - 181200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE NORTHERN PLAINS...UPPER MIDWEST...MID ATLANTIC...AND SOUTHERN
NEW ENGLAND....

...SUMMARY...
One or two clusters of thunderstorms may develop and gradually pose
a risk for damaging wind gusts from the northern High Plains into
the Midwest this afternoon and tonight. Damaging thunderstorm wind
gusts may also occur across parts of the northern Mid Atlantic into
southern New England late this afternoon and evening.

...Northern Plains into Upper Midwest...
A broad upper ridge remains in place over southern/central U.S
today. Several weak perturbations will top the ridge during this
forecast period, affecting much of the northern Plains and upper
Midwest. Each of these smaller-scale shortwave troughs will
potentially be associated with a cluster of thunderstorms.
Sufficient low-level moisture and 25-35 knots of westerly flow aloft
pose some conditional risk of severe storms throughout this region,
but considerable uncertainty on the timing and placement of
convection precludes upgrading any areas to SLGT at this time.
Multiple areas of ongoing convection this morning further complicate
the forecast. Perhaps by 1630z, areas of stronger daytime heating/destabilization will allow better focus of the severe
outlook.

...Mid Atlantic into southern New England...
A cold front currently extends from OH northeastward into the St.
Lawrence Valley. Forecast soundings ahead of the front show weak
mid-level lapse rates and limited mid-level dry air. However,
strong heating into the 80s and 90s F, coupled with dewpoints near
70F will yield MLCAPE around 1000 J/kg. Sufficient westerly flow
aloft and frontal forcing may be sufficient for isolated strong
storms capable of locally gusty/damaging winds this afternoon.

..Hart/Dean.. 08/17/2025

$$

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ACUS01 KWNS 171632
SWODY1
SPC AC 171630

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1130 AM CDT Sun Aug 17 2025

Valid 171630Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE MIDDLE MISSOURI VALLEY VICINITY...

...SUMMARY...
One or two clusters of thunderstorms may develop and gradually pose
a risk for damaging wind gusts from the northern High Plains into
the Midwest this afternoon and tonight. Damaging thunderstorm wind
gusts may also occur across parts of the northern Mid Atlantic into
southern New England late this afternoon and evening.

...Northern/Central Plains into Upper Midwest...
The combination of close proximity to the upper ridge that covers
much of the central/southern CONUS, lack of more defined synoptic
features, and ample low-level moisture and buoyancy yields a complex
and uncertain forecast from the northern/central Plains into the
Midwest today and tonight. Recent satellite and radar imagery
depicts two MCVs across the region, one over central SD and the
other across central NE. Surface analysis also shows a low over the
central SD/NE border, along the northern periphery of the NE MCV. A
mix of convective outflow, cloud cover, and a formally more defined
surface boundary has resulted in a warm-front-like feature extending southeastward from this surface low through central IA. All of these
features will likely play a role in thunderstorm development today.

The general expectation is for mesoscale ascent attendant to the
surface low and MCV to yield increasing thunderstorm development
across southeast SD and northeast NE over the next few hours. A
sharpening warm front will likely shift northward, providing a
favored corridor for storm progression, with the ongoing storms
continuing downstream along this corridor into southwest MN and northwest/north-central IA. Damaging gusts will be the primary risk,
with severe coverage expected to become high enough to merit
introducing 15% wind probabilities. A more stable airmass to the north/northeast of the boundary should limit the severe risk over
central MN and central WI.

Much of the guidance also shows evening thunderstorm development
beginning in eastern WY/southwest SD/NE Panhandle region before then
spreading eastward/southeastward with time. This activity appears to
be initially associated with low-level convergence along the lee
troughing, with its progression southeastward likely tied to an
increasing low-level jet. Isolated hail is possible initially with a
few stronger gusts then possible overnight.

...Northern Rockies/northern High Plains...
Scattered high-based thunderstorms are expected this afternoon and
evening as ascent attendant the shortwave trough currently moving
through eastern OR spreads into the region. Combination of moderate
mid-level southwesterly flow, steep low-level lapse rates, and high
cloud bases could contribute to isolated strong to severe gusts
within these storms as they gradually move from southwest MT into central/southeastern MT.

...Mid Atlantic into southern New England...
Recent surface analysis places a cold front from northern ME
southwestward through western NY and northwest PA in northern OH.
Mid-level lapse rates are weak, and the relatively warm profiles
will likely limit buoyancy, despite dewpoints in the mid to upper
60s. However, strong heating into the 80s and 90s F and steep
low-level lapse rates combined with modest westerly flow aloft and
frontal forcing may be sufficient for isolated strong storms capable
of locally gusty/damaging winds this afternoon. Locally higher
probability for damaging gusts appears to exist across southern ME,
where greater deep-layer shear is presence, and over the northern
Mid-Atlantic where dewpoints and buoyancy will be highest.

..Mosier/Grams.. 08/17/2025

$$

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ACUS01 KWNS 172003
SWODY1
SPC AC 172001

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0301 PM CDT Sun Aug 17 2025

Valid 172000Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE MIDDLE MISSOURI VALLEY VICINITY...

...SUMMARY...
One or two clusters of thunderstorms may develop and gradually pose
a risk for damaging wind gusts from the northern High Plains into
the Midwest this afternoon and tonight. Damaging thunderstorm wind
gusts may also occur across parts of the northern Mid Atlantic into
southern New England late this afternoon and evening.

...20Z Update...
Preceding a remnant MCV tracking northeastward across parts of
southeastern SD, an elevated cluster of thunderstorms is spreading northeastward from east-central SD into southwest MN. Ahead of this
activity, earlier stable/billow clouds have eroded along/north of a
surface boundary draped across southwestern MN, where diurnal
heating amid lower 70s dewpoints is contributing to gradual air mass recovery/destabilization. Given this continued destabilization, the
Slight Risk was expanded slightly northward, and was also trimmed on
the western edge in the wake of the MCV.

Farther east, the Marginal Risk was expanded slightly westward into northeastern WV -- ahead of an ongoing cluster of thunderstorms with
a history of wind damage. See MCD 1975 for more details. For details
on the near-term severe threat over the Black Hills vicinity,
reference MCD 1976.

..Weinman.. 08/17/2025

.PREV DISCUSSION... /ISSUED 1130 AM CDT Sun Aug 17 2025/

...Northern/Central Plains into Upper Midwest...
The combination of close proximity to the upper ridge that covers
much of the central/southern CONUS, lack of more defined synoptic
features, and ample low-level moisture and buoyancy yields a complex
and uncertain forecast from the northern/central Plains into the
Midwest today and tonight. Recent satellite and radar imagery
depicts two MCVs across the region, one over central SD and the
other across central NE. Surface analysis also shows a low over the
central SD/NE border, along the northern periphery of the NE MCV. A
mix of convective outflow, cloud cover, and a formally more defined
surface boundary has resulted in a warm-front-like feature extending southeastward from this surface low through central IA. All of these
features will likely play a role in thunderstorm development today.

The general expectation is for mesoscale ascent attendant to the
surface low and MCV to yield increasing thunderstorm development
across southeast SD and northeast NE over the next few hours. A
sharpening warm front will likely shift northward, providing a
favored corridor for storm progression, with the ongoing storms
continuing downstream along this corridor into southwest MN and northwest/north-central IA. Damaging gusts will be the primary risk,
with severe coverage expected to become high enough to merit
introducing 15% wind probabilities. A more stable airmass to the north/northeast of the boundary should limit the severe risk over
central MN and central WI.

Much of the guidance also shows evening thunderstorm development
beginning in eastern WY/southwest SD/NE Panhandle region before then
spreading eastward/southeastward with time. This activity appears to
be initially associated with low-level convergence along the lee
troughing, with its progression southeastward likely tied to an
increasing low-level jet. Isolated hail is possible initially with a
few stronger gusts then possible overnight.

...Northern Rockies/northern High Plains...
Scattered high-based thunderstorms are expected this afternoon and
evening as ascent attendant the shortwave trough currently moving
through eastern OR spreads into the region. Combination of moderate
mid-level southwesterly flow, steep low-level lapse rates, and high
cloud bases could contribute to isolated strong to severe gusts
within these storms as they gradually move from southwest MT into central/southeastern MT.

...Mid Atlantic into southern New England...
Recent surface analysis places a cold front from northern ME
southwestward through western NY and northwest PA in northern OH.
Mid-level lapse rates are weak, and the relatively warm profiles
will likely limit buoyancy, despite dewpoints in the mid to upper
60s. However, strong heating into the 80s and 90s F and steep
low-level lapse rates combined with modest westerly flow aloft and
frontal forcing may be sufficient for isolated strong storms capable
of locally gusty/damaging winds this afternoon. Locally higher
probability for damaging gusts appears to exist across southern ME,
where greater deep-layer shear is presence, and over the northern
Mid-Atlantic where dewpoints and buoyancy will be highest.

$$

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ACUS01 KWNS 180102
SWODY1
SPC AC 180100

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0800 PM CDT Sun Aug 17 2025

Valid 180100Z - 181200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PORTIONS OF
THE CENTRAL/NORTHERN PLAINS AND UPPER MIDWEST...

...SUMMARY...
Scattered thunderstorms over the central and northern Plains may
pose a threat for damaging gusts and hail tonight, while a brief
tornado remains possible over the Midwest this evening.

...Central and northern Plains...
Weak ascent from a broad shortwave trough, visible in evening
water-vapor imagery, is supporting scattered thunderstorm
development across portions of western NE and SD this evening. Some
clustering of initial cells has been noted over the High Plains this
evening. Slight enhancement of southwesterly flow aloft attendant to
the broad shortwave trough suggests some upscale growth is possible
over southern SD and northern/central NE this evening into tonight.
Aided by and increasing southwesterly low-level jet, severe gusts
are possible over parts of NE and southern SD with a loosely
organized cluster/MCS progressing east/southestward.

Farther north along the front in the eastern Dakotas, scattered
storms remain possible tonight, especially as low-level mass
response increases at the nose of the low-level jet. Likely
elevated, sporadic hail and or isolated damaging winds would be
possible with any stronger clusters. Confidence in this scenario is
low owing the weak but persistent subsidence in the wake of the MCV
farther east.

...IA/MN...
Ahead of a diffuse MCV, scattered thunderstorms have developed along
an east-west oriented frontal zone. Along and south of this front,
very moist surface conditions are supporting large buoyancy. Area
VADs and forecast soundings show modest westerly flow aloft,
primarily along the cool side of the boundary. Still, slight
enhancement of low-level shear profiles and vertical vorticity along
the wind shift could support a brief supercell/tornado threat with
occasional stronger updrafts into this evening. With time, the
threat should begin to diminish later tonight as the boundary layer
begins to cool and the MCV continues eastward.

...Northern Rockies/northern High Plains...
Scattered high-based thunderstorms ongoing this evening should
continue into tonight as ascent attendant the shortwave trough over
the Northwest spreads eastward. Moderate southwesterly flow aloft,
and weak buoyancy atop steep low-level lapse rates will remain
supportive of isolated severe gusts with the stronger downdrafts.
The severe risk should steadily progress eastward into southeastern
MT and the far western Dakotas before weakening after sunset
tonight.

...Mid Atlantic...
Lingering scattered thunderstorms may pose a risk for a damaging
wind gust or two for a couple more hours this evening across
portions of the DelMarVa. While general convective trends continue
to suggest a decreasing threat with nocturnal stabilization
underway, a stray gust or two cannot be ruled out before storms off
shore tonight.

..Lyons.. 08/18/2025

$$

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ACUS01 KWNS 180549
SWODY1
SPC AC 180548

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1248 AM CDT Mon Aug 18 2025

Valid 181200Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS PORTIONS OF
THE CENTRAL HIGH PLAINS...

...SUMMARY...
Strong to severe storms capable of damaging winds are possible in
parts of the Upper Midwest today. Isolated to widely scattered
storms with large hail and severe winds are possible in parts of the central/northern Plains through tonight.

...Central High Plains...
A broad upper trough over the northern Plains will move east today
with an attendant surface low and cold front also moving east.
Behind the departing surface low, weak upslope flow is expected
across portions of western SD, northeastern WY. Strong heating and
steep mid-level lapse rates should allow for diurnal destabilization
with widely scattered thunderstorms expected along a lee trough by
the afternoon. Elongated hodographs, courtesy of 30-40 kt of
westerly flow aloft, will allow for some organized storms including
supercells or clusters. Steep mid-level lapse rates, and moderate
buoyancy will support a hail risk.

Farther south, stronger heating and mixing will limit low-level
moisture across southeastern WY and northeastern CO. Still, enough
CAPE should be present for scattered high-based storms near peak
heating. The steep low-level lapse rates and any clustering that
develops should support damaging winds as storms spread eastward
into northeast CO and western NE.

Some potential exists for a longer-lived cluster to spread eastward
into central/eastern NE and northern KS overnight. Should this
occur, damaging winds and some hail would be the primary concerns,
though this scenario remains highly uncertain given weaker forecast
low-level jet.

...Midwest...
One or more clusters of thunderstorms or an MCV is expected to be
ongoing at the start of the period in the vicinity of the warm front
across portions of IA/MN, casting significant uncertainty on the
overall convective evolution for the day. Filtered diurnal heating
and nebulous ascent from the broad trough over the northern Plains
could support continuation of these storms and additional
development into southern WI and northern IL this afternoon. While complications abound, substantial buoyancy (3000-4000 J/kg of
MLCAPE) and dewpoints in the mid 70s F south of the composite
front/remnant outflow will be supportive of occasional vigorous
updrafts. Modest enhancement of the mid and upper-level flow could
support a few semi-organized clusters or transient supercells with
damaging wind potential. Given the potential for outflow or
thunderstorm clusters to significantly alter the environment,
confidence in higher wind probabilities is low.

...Southwest into central Montana...
Despite a strong ridge building into the northern Rockies,
sufficient moisture may promote thunderstorm development in the
higher terrain this afternoon. 20-30 kt of flow aloft will be
sufficient to support at least marginally organized storms. However,
strong mixing during the afternoon could limit buoyancy and storm
coverage. Occasional strong, gusty outflow winds are possible with
any high-based storms, but confidence in severe potential remains
low.

..Lyons/Kerr.. 08/18/2025

$$

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ACUS01 KWNS 181236
SWODY1
SPC AC 181235

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0735 AM CDT Mon Aug 18 2025

Valid 181300Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF THE CENTRAL/NORTHERN PLAINS...AND OVER PARTS OF THE MIDWEST....

...SUMMARY...
Strong to severe storms capable of damaging winds are possible in
parts of the Midwest today. Widely scattered storms with large hail
and severe winds are possible in parts of the central/northern
Plains through tonight.

...IA/WI/IL...
A long-lived MCS continues to track eastward across central IA this
morning. Visible satellite imagery shows the potential for
considerable daytime heating ahead of this activity across parts of
eastern IA/southern WI/northern IL, where temperatures will warm
into the 90s. Ample low-level moisture will yield afternoon MLCAPE
values around 3000 J/kg, along with sufficient westerly flow aloft
for some convective organization. It is unclear whether current
activity will intensify, or new storms will form later today.
Regardless, this region will see the potential for strong/severe
storms capable of damaging wind gusts. A tornado or two is also
possible, given the backed low-level winds and east-west baroclinic
zone along the WI/IL border. Have added a SLGT risk for this
scenario.

...Northeast CO into SD/NE/KS...
Strong heating and ample low/mid level moisture will promote the
development of scattered thunderstorms by mid-afternoon over the
foothills and plains of central/eastern CO. Other more isolated
storms are expected farther north across western NE into the Black
Hills region. All of these storms will be relatively high-based,
posing a risk of damaging wind gusts. Sufficient westerly flow will
also aid in a few transient supercells capable of large hail. These
storms may persist into the evening, tracking into central NE before
weakening.

...MO/AR...
Clear skies are evident this morning across central/southern MO and
much of AR. Hot and humid conditions will ensue with temperatures
reaching the upper 90s. Most CAM solutions suggest widely scattered
afternoon thunderstorm development in this environment of steep
low-level lapse rates and 1500-2000 J/kg of MLCAPE. The strongest
storms will be capable of locally damaging wind gusts.

..Hart/Dean.. 08/18/2025

$$

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ACUS01 KWNS 181630
SWODY1
SPC AC 181629

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1129 AM CDT Mon Aug 18 2025

Valid 181630Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS ACROSS SOUTHERN WI
AND NORTHERN IL...AND ACROSS PORTIONS OF THE NORTHERN AND CENTRAL
PLAINS...

...SUMMARY...
Strong to severe storms capable of damaging winds are possible in
parts of the Midwest today. Widely scattered storms with large hail
and severe winds are possible in parts of the central/northern
Plains through tonight.

...Mid MS Valley...
Extensive outflow from last night's MCS currently extends from
extreme southwest WI southwestward through eastern IA and
north-central MO into eastern KS. This outflow has been moving
quickly eastward/southeastward this morning, and this trend is
expected to continue, although some slowing of its progression speed
is possible over time. The downstream airmass across from southern
WI and IL is characterized by dewpoints in the low to mid 70s.
Mid-level lapse rates are generally poor across the region, but
heating of this very moist airmass will still result in strong to
very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late
afternoon.

Strong to severe storms are possible along this outflow as it
impinges on this moist and buoyant airmass. Current trends suggest
the greatest severe potential will exist this afternoon across
southern WI and northern IL, where slightly stronger mid-level flow,
backed surface winds, and an east-west baroclinic zone exists.
Recently issued MCD 1983 addresses the short-term severe potential
for this area.

...Central High Plains into the northern/central Plains...
Strong heating and ample low/mid level moisture will promote the
development of scattered thunderstorms by mid-afternoon over the
foothills and plains of central/eastern CO. Additional isolated
storms are possible farther north across western NE into the Black
Hills region. Much of this area is within a corridor of modest
mid-level flow on the northern periphery of the upper ridging
covering the southern CONUS. Resulting modest shear may be enough
for hail production with the initial development before these
high-based storms trend towards outflow-dominant structures with
time. These storms may persist into the evening, with an attendant
threat for strong to severe gusts progressing into central NE before
weakening.

...MO/AR...
Clear skies and strong diurnal heating are expected across
central/southern MO and much of AR. Temperatures in the upper 90s
are expected, with dewpoints remaining in the mid 60s despite strong
mixing. These hot and humid conditions will result in strong
buoyancy this afternoon, with most guidance suggesting MLCAPE around
2000 J/kg. Shear will be weak, yielding mostly disorganized
multicells, but the strongest storms will be capable of locally
damaging wind gusts.

..Mosier/Wendt.. 08/18/2025

$$

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ACUS01 KWNS 182000
SWODY1
SPC AC 181959

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0259 PM CDT Mon Aug 18 2025

Valid 182000Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FOR PORTIONS OF
NORTHERN ILLINOIS AND PARTS OF THE CENTRAL AND NORTHERN PLAINS...

...SUMMARY...
Strong to severe storms capable of damaging winds are possible in
parts of the Midwest today. Widely scattered storms with large hail
and severe winds are possible in parts of the central/northern
Plains through tonight.

...20Z Update...
The primary change to the current Day 1 Outlook was to trim severe probabilities across portions of southern Wisconsin, where the
passage of an MCS has resulted in low-level stabilization.
Otherwise, only minor changes was made to severe/thunder
probabilities to reflect the latest guidance and observations.

..Squitieri.. 08/18/2025

.PREV DISCUSSION... /ISSUED 1129 AM CDT Mon Aug 18 2025/

...Mid MS Valley...
Extensive outflow from last night's MCS currently extends from
extreme southwest WI southwestward through eastern IA and
north-central MO into eastern KS. This outflow has been moving
quickly eastward/southeastward this morning, and this trend is
expected to continue, although some slowing of its progression speed
is possible over time. The downstream airmass across from southern
WI and IL is characterized by dewpoints in the low to mid 70s.
Mid-level lapse rates are generally poor across the region, but
heating of this very moist airmass will still result in strong to
very strong buoyancy (i.e. MLCAPE around 3000 J/kg) by late
afternoon.

Strong to severe storms are possible along this outflow as it
impinges on this moist and buoyant airmass. Current trends suggest
the greatest severe potential will exist this afternoon across
southern WI and northern IL, where slightly stronger mid-level flow,
backed surface winds, and an east-west baroclinic zone exists.
Recently issued MCD 1983 addresses the short-term severe potential
for this area.

...Central High Plains into the northern/central Plains...
Strong heating and ample low/mid level moisture will promote the
development of scattered thunderstorms by mid-afternoon over the
foothills and plains of central/eastern CO. Additional isolated
storms are possible farther north across western NE into the Black
Hills region. Much of this area is within a corridor of modest
mid-level flow on the northern periphery of the upper ridging
covering the southern CONUS. Resulting modest shear may be enough
for hail production with the initial development before these
high-based storms trend towards outflow-dominant structures with
time. These storms may persist into the evening, with an attendant
threat for strong to severe gusts progressing into central NE before
weakening.

...MO/AR...
Clear skies and strong diurnal heating are expected across
central/southern MO and much of AR. Temperatures in the upper 90s
are expected, with dewpoints remaining in the mid 60s despite strong
mixing. These hot and humid conditions will result in strong
buoyancy this afternoon, with most guidance suggesting MLCAPE around
2000 J/kg. Shear will be weak, yielding mostly disorganized
multicells, but the strongest storms will be capable of locally
damaging wind gusts.

$$

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ACUS01 KWNS 190051
SWODY1
SPC AC 190049

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0749 PM CDT Mon Aug 18 2025

Valid 190100Z - 191200Z

...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS THIS EVENING
ACROSS PARTS OF NORTHERN KANSAS AND SOUTHERN NEBRASKA...AND PARTS OF
SOUTH CENTRAL SOUTH DAKOTA...

...SUMMARY...
A clustering of storms may continue to generate strong to severe
wind gusts across parts of the central Great Plains through much of
the evening.

...01Z Update...

...Central Great Plains...
A low-level convergence zone has become a focus for thunderstorm
development near/north of the I-70 corridor of western Kansas, with
additional thunderstorm activity approaching the eastern Colorado
state border vicinity, aided by a weak short wave impulse
progressing around the northeastern periphery of a prominent
mid-level high centered east of the Four Corners. This activity,
and associated convective outflow, may continue to gradually
consolidate into a further enlarging convective cluster, which could
eventually generate a notable mesoscale convective vortex while
propagating slowly eastward within otherwise light westerly
deep-layer mean flow across the central Great Plains.

A deeply mixed boundary-layer across the high plains has contributed
to an environment conducive to downbursts and surface cold pool
development. As the cold pools consolidate and spread into a much
more moist boundary layer with large potential instability across
south central Nebraska/central Kansas, it is possible that forcing
for ascent may overcome increasing inhibition associated with
boundary layer cooling, and maintain vigorous convective development
into and through the overnight hours.

...Dakotas...
Widely scattered strong boundary-layer based thunderstorm
development is generally expected to wane over the next few hours,
as mid-level inhibition increases with the loss of daytime heating.

..Kerr.. 08/19/2025

$$

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ACUS01 KWNS 190537
SWODY1
SPC AC 190535

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1235 AM CDT Tue Aug 19 2025

Valid 191200Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS AFTERNOON
AND EVENING ACROSS PARTS OF THE CENTRAL GREAT PLAINS AND OZARK
PLATEAU INTO OHIO VALLEY...AND THIS EVENING INTO THE OVERNIGHT HOURS
ACROSS PARTS OF WESTERN MONTANA...

...SUMMARY...
Scattered strong thunderstorm activity may impact a corridor from
the central Great Plains into the Ohio Valley this afternoon and
evening, accompanied by locally strong to severe wind gusts. A
cluster of thunderstorms may also develop across and northeast of
the mountains of western Montana accompanied by strong to severe
wind gusts this evening into the overnight hours.

...Discussion...
Models indicate that a prominent mid/upper high centered near/east
of the Four Corners will be maintained through this period. To the
north of this circulation, heights are forecast to build through the
day along a broad axis extending north-northeastward into the
eastern Canadian Prairies, ahead of a fairly vigorous low and south-southwestward trailing troughing migrating inland of the
British Columbia/Pacific Northwest coast.

Downstream, to the south of the stronger westerlies, it appears that
weak mid-level troughing will dig across and southeast of the Great
Lakes region, perhaps suppressing mid-level heights across parts of
the northern Mid Atlantic into southern Appalachians by 12Z
Wednesday, to the northwest of Hurricane Erin as it continues a slow north-northwestward migration to the east/northeast of the Bahamas.
On the trailing, southwestern flank of this troughing, a remnant
convectively enhanced perturbation initially across Kansas may
slowly dig southward toward the southern Great Plains Red River
vicinity.

In lower levels, a weak surface low is forecast to slowly progress
across southern portions of the Great Lakes region, with a weak
trailing surface front, reinforced in segments by convective
outflow, advancing southward into the Ohio Valley, Mid South and Red
River Valley by late tonight.

...Central Great Plains into Ohio Valley...
Seasonably high boundary-layer moisture content along/ahead of the
southward advancing front is forecast to contribute to the
development of moderate to strong potential instability with daytime
heating, beneath a residual plume of relatively steep
lower/mid-tropospheric lapse rates, particularly across parts of the
central Great Plains into Ozark Plateau. Coincident with and
subsequent to peak boundary-layer destabilization, weak mid-level
height falls may contribute to considerable upscale growing
thunderstorm development during the mid to late afternoon and
evening. Although rather weak deep-layer mean wind fields and shear
are likely to limit the risk for organized severe convection,
thermodynamic profiles may still be conducive to localized
downbursts in stronger storms, and gusty winds occasionally
approaching severe limits along consolidating and strengthening
southward propagating cold pools into this evening.

...Northern Rockies...
Although the time of arrival of mid-level height falls/forcing for
ascent downstream of the inland progressing mid-level troughing may
be sometime this evening, it appears that this will be preceded by
sufficient moistening in the presence of steep lapse rates to
support thunderstorm development. Models suggest that convection
will initiate across the mountains of western Montana this evening,
before consolidating and spreading in a cluster east of the higher
terrain through north central Montana overnight. Given
west-southwesterly mean flow strengthening to 30-40+ kt in the
cloud-bearing layer, and a residual deep sub-cloud mixed-layer,
there may be sufficient downward mixing of momentum to contribute to
a few strong to severe surface gusts.

..Kerr/Lyons.. 08/19/2025

$$

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ACUS01 KWNS 191255
SWODY1
SPC AC 191253

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0753 AM CDT Tue Aug 19 2025

Valid 191300Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS THE
SOUTH-CENTRAL PLAINS AND OZARKS TO OHIO VALLEY AND NORTHERN
ROCKIES...

...SUMMARY...
Scattered strong to severe thunderstorms capable of damaging winds
will be possible across the south-central Great Plains and Ozarks to
the Ohio Valley this afternoon and evening. Isolated severe
thunderstorms may also occur across parts of the northern Rockies
including western and northern Montana.

...South-central Plains and Ozarks to Ohio Valley...
Outside of a few areas of lingering early day convection/small-scale
outflows, a hot air mass and relatively high moisture content will
reside to the south of a synoptic front extending from the
south-central Plains to the Midwest/Ohio Valley. Moderate to strong
buoyancy with daytime heating, beneath a residual plume of
relatively steep lower/mid-tropospheric lapse rates, will exist
particularly across parts of the south-central Plains to Ozark
Plateau, including parts of Kansas/Oklahoma to Arkansas/southern
Missouri. As storms diurnally develop/increase, upscale-growing
thunderstorm development should occur during the mid to late
afternoon and early evening. While weak deep-layer winds and shear
are likely to limit the risk for organized severe convection,
thermodynamic profiles will be conducive for downbursts and
severe-caliber wind gusts with the stronger storms, particularly
this afternoon through around sunset.

...Northern Rockies including western/northern Montana...
The late-day arrival of weak height falls and approaching mid-level perturbation should influence isolated thunderstorm development late
this afternoon, and more so into this evening, across parts of
northern Idaho in western and eventually northern Montana.
Sufficient moisture/buoyancy near and behind a surface front, along
with strengthening flow aloft, will support the possibility of some
severe storms, and potentially some clustering/organization to the
storms as they progress across western/northern Montana.
West-southwesterly mean flow strengthening to 30-40+ kt in the
cloud-bearing layer, and a residual deep sub-cloud mixed-layer, will
likely be sufficient for downward mixing of momentum to contribute
to a few strong to severe wind gusts.

..Guyer/Dean.. 08/19/2025

$$

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ACUS01 KWNS 191629
SWODY1
SPC AC 191628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Tue Aug 19 2025

Valid 191630Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OHIO VALLEY TO THE SOUTHERN/CENTRAL PLAINS...AND OVER PORTIONS
OF WESTERN/NORTHERN MONTANA...

...SUMMARY...
Scattered thunderstorms capable of producing occasional damaging
winds will be possible across parts of the south-central Plains and
Ozarks to the Ohio Valley this afternoon and evening. Isolated
severe thunderstorms may also occur this evening across parts of
western and northern Montana.

...Ohio Valley to the Central/Southern Plains...
Upper ridging will remain prominent today across the Southwest and southern/central Rockies, as a weak mid/upper-level trough moves east-southeastward across the Great Lakes and OH Valley regions. At
the surface, a weak cold front is forecast to advance
east-southeastward across parts of the OH Valley and mid MS Valley
today, and more slowly southward over portions of the
central/southern Plains while weakening. This boundary should aid in
at least scattered thunderstorm development through the afternoon as
diurnal heating of a moist airmass along/south of the front occurs.
While deep-layer flow and related shear are expected to remain
generally weak, moderate to strong instability and the steepening of
low-level lapse rates may support occasional strong to damaging
winds with water-loaded downdrafts within the stronger cores. Only
minor adjustments have been made to the broad Marginal Risk based on
latest observational and short-term guidance trends.

...Northern Rockies/High Plains...
An embedded mid-level shortwave trough will advance northeastward
this evening and overnight across parts of the northern Rockies and
adjacent High Plains on the western to northern periphery of
prominent upper ridging over the Southwest. Isolated to perhaps
widely scattered thunderstorms should develop through the evening
hours across parts of western MT and vicinity as large-scale ascent
associated with the shortwave trough overspreads the northern
Rockies. Instability is forecast to remain rather limited, but
steepened lapse rates aloft and a well-mixed boundary layer could
still aid in some convective downdraft enhancement, with isolated
strong to severe gusts possible as convection spreads northeastward
towards the international border.

...Coastal Texas...
A weak mid-level perturbation with ongoing thunderstorms along parts
of the middle TX Coast should continue south-southwestward this
afternoon and evening. Low/mid-level flow should remain modest,
which will generally limit thunderstorm organization. Still, some
clustering could support isolated strong/gusty winds in the presence
of increasing instability this afternoon across parts of
south-central TX and the lower TX Coast. Confidence in
severe-caliber gusts remains too low to include any severe
probabilities at this time.

..Gleason/Wendt.. 08/19/2025

$$

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ACUS01 KWNS 191948
SWODY1
SPC AC 191947

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0247 PM CDT Tue Aug 19 2025

Valid 192000Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
THE OHIO VALLEY TO THE SOUTHERN/CENTRAL PLAINS AND OVER PORTIONS OF WESTERN/NORTHERN MONTANA...

...SUMMARY...
Scattered thunderstorms capable of producing occasional damaging
winds will be possible across parts of the south-central Plains and
Ozarks to the Ohio Valley this afternoon and evening. Isolated
severe thunderstorms may also occur this evening across parts of
western and northern Montana.

...20z Update...
The Marginal Risk was trimmed across northern/east-central Kansas
into southern Missouri. Morning convection associated with a remnant
MCV has diminished, with more stable near surface conditions in it's
wake. Visible satellite shows decreasing cloud cover and dew points
lowering amid warming and mixing. CAM guidance shows low potential
for some redevelopment of thunderstorm activity along the front
later in the evening. Some portion on the Marginal was left across
southern Missouri to account for this risk.

Otherwise, the outlook remains on track. See previous discussion
below for more information.

..Thornton.. 08/19/2025

.PREV DISCUSSION... /ISSUED 1128 AM CDT Tue Aug 19 2025/

...Ohio Valley to the Central/Southern Plains...
Upper ridging will remain prominent today across the Southwest and southern/central Rockies, as a weak mid/upper-level trough moves east-southeastward across the Great Lakes and OH Valley regions. At
the surface, a weak cold front is forecast to advance
east-southeastward across parts of the OH Valley and mid MS Valley
today, and more slowly southward over portions of the
central/southern Plains while weakening. This boundary should aid in
at least scattered thunderstorm development through the afternoon as
diurnal heating of a moist airmass along/south of the front occurs.
While deep-layer flow and related shear are expected to remain
generally weak, moderate to strong instability and the steepening of
low-level lapse rates may support occasional strong to damaging
winds with water-loaded downdrafts within the stronger cores. Only
minor adjustments have been made to the broad Marginal Risk based on
latest observational and short-term guidance trends.

...Northern Rockies/High Plains...
An embedded mid-level shortwave trough will advance northeastward
this evening and overnight across parts of the northern Rockies and
adjacent High Plains on the western to northern periphery of
prominent upper ridging over the Southwest. Isolated to perhaps
widely scattered thunderstorms should develop through the evening
hours across parts of western MT and vicinity as large-scale ascent
associated with the shortwave trough overspreads the northern
Rockies. Instability is forecast to remain rather limited, but
steepened lapse rates aloft and a well-mixed boundary layer could
still aid in some convective downdraft enhancement, with isolated
strong to severe gusts possible as convection spreads northeastward
towards the international border.

...Coastal Texas...
A weak mid-level perturbation with ongoing thunderstorms along parts
of the middle TX Coast should continue south-southwestward this
afternoon and evening. Low/mid-level flow should remain modest,
which will generally limit thunderstorm organization. Still, some
clustering could support isolated strong/gusty winds in the presence
of increasing instability this afternoon across parts of
south-central TX and the lower TX Coast. Confidence in
severe-caliber gusts remains too low to include any severe
probabilities at this time.

$$

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ACUS01 KWNS 200032
SWODY1
SPC AC 200031

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0731 PM CDT Tue Aug 19 2025

Valid 200100Z - 201200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS THIS EVENING
INTO THE OVERNIGHT HOURS ACROSS PARTS OF WESTERN INTO NORTH CENTRAL
MONTANA...

...SUMMARY...
Strong to severe wind gusts may develop with a consolidating cluster
of thunderstorms across western through north central Montana this
evening into the overnight hours.

...01Z Update...

...Northern Rockies...
Thunderstorms have begun to initiate across the Bitterroots
vicinity, with deepening convection also evident to the lee of the
mountains of western Montana, between Great Falls and Cut Bank.
Although the hot and deeply mixed boundary layer which has evolved
across the region appears only characterized by weak CAPE, models
suggest that mid-level forcing for ascent overspreading the region
will probably become supportive of a consolidating cluster, in the
presence of cloud-bearing layer mean flow strengthening to 30-40+
kt. Even with onset of boundary-layer cooling within the next
couple of hours, sub-cloud thermodynamic profiles will remain
conducive to strengthening downward momentum transfer accompanied by
surface gusts approaching or exceeding severe limits. As convection
approaches better boundary-layer moisture across the Havre vicinity
by late evening, more unstable updraft inflow might support further intensification of thunderstorms before spreading across the
international border.

..Kerr.. 08/20/2025

$$

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ACUS01 KWNS 200536
SWODY1
SPC AC 200534

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1234 AM CDT Wed Aug 20 2025

Valid 201200Z - 211200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS TODAY ACROSS THE
WESTERN AND CENTRAL GULF COAST STATES AND THE INTERNATIONAL BORDER
VICINITY OF NORTH DAKOTA...

...SUMMARY...
Scattered thunderstorms developing this afternoon and evening across
the western and central Gulf Coast states may pose a risk for
localized potentially damaging wind gusts. Otherwise, there appears
some risk for an isolated severe thunderstorm or two across parts of
northern North Dakota.

...Discussion...
Models indicate that a prominent mid/upper high will be maintained
over the Four Corners vicinity through this period. However,
initially amplified ridging extending to its north, as far as the
Canadian Prairies, appears likely to become suppressed southeastward
toward the central international border vicinity, as a significant
short wave perturbation progresses east of the Canadian Rockies into
Prairies by late tonight. It appears that this may be accompanied
by weak cyclogenesis across southern Saskatchewan toward the central Saskatchewan/Manitoba border vicinity, with a trailing cold front
advancing across the Montana international border by late tonight.

At the same time, an increasingly sheared perturbation will continue progressing through weak larger-scale mid-level troughing digging
across the Northeast, and southeastward around the periphery of the
high, across the Ohio/Tennessee Valleys and southern Great Plains.
To the southeast of this feature, Hurricane Erin is forecast to turn
slowly north-northeastward, offshore of the southern through middle
Atlantic Seaboard.

...Gulf Coast States...
A diffuse surface frontal zone, reinforced in segments by convective
outflow, will continue slowly southward ahead of the mid-level shear
axis, likely reaching portions of central Texas through Louisiana
and central/northern Mississippi and Alabama by mid to late
afternoon. Along and ahead of this front, a corridor of stronger
heating of a seasonably moist boundary layer, perhaps still
coincident with a residual plume of relatively steep
lower/mid-tropospheric lapse rates, may continue to contribute to
thermodynamic profiles supportive of localized downbursts and gusty
winds on convectively generated surface cold pools. It is not clear
that the severe threat will be any more widespread than the sparse
coverage of preceding days, but it may perhaps be marginally
sufficient to justify 5 percent severe wind probabilities.

...North Dakota...
Models indicate that a narrow corridor of moderate to large
potential instability may develop along/ahead of the surface cold
front, a pre-frontal surface trough and developing warm frontal zone
across parts of the Dakotas into eastern Saskatchewan by late this
afternoon. However, beneath the nose of a plume of warm and capping
elevated mixed-layer air, mid/upper support for the initiation of boundary-layer based thunderstorm development is forecast to
generally remain to the north of the international border.

While the risk for severe thunderstorms appears largely conditional,
guidance does indicate that a weak surface low may develop within
the pre-frontal troughing and provide a potential focus for
convective development across northwestern North Dakota late this
afternoon and evening. If this forcing, coupled with the approach
of convective temperatures, is sufficient to overcome the mid-level
inhibition, forecast soundings indicate the environment will be
conducive to supercell development.

..Kerr/Lyons.. 08/20/2025

$$

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ACUS01 KWNS 201231
SWODY1
SPC AC 201230

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0730 AM CDT Wed Aug 20 2025

Valid 201300Z - 211200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
TEXAS/DEEP SOUTH AND NORTHERN PLAINS...

...SUMMARY...
Scattered thunderstorms from Texas across the Lower Mississippi
Valley and Gulf Coast states may pose a risk for localized damaging
wind gusts this afternoon and evening. Isolated severe thunderstorms
may also occur across eastern Montana and northern North Dakota.

...Texas to Lower Mississippi Valley/Gulf Coast States...
A convectively augmented effective front will continue to progress
southward, southward-shifting the potential for microburst-related
wind damage regionally. Diurnal heating of a moist boundary layer
will result in a moderately to strongly unstable and weakly capped
airmass by afternoon, with the strongest buoyancy (2500+ J/kg
MLCAPE) expected across central/east Texas east-northeastward to Mississippi/western Alabama/southern Tennessee. Some small-scale
clusters may evolve, but weak vertical shear will otherwise tend to
keep the overall pulse-type damaging wind potential very isolated.

...Northern Plains...
The region will be influenced by late-day/nighttime height falls as
a shortwave trough emerges eastward from the Canadian Rockies, with
an eastward-advancing cold front moving across eastern Montana into
North Dakota tonight. A narrow corridor of moderate to large
buoyancy is expected along/ahead of the surface cold front, and near
a pre-frontal surface trough. Beneath a plume of warm elevated
mixed-layer air, mid/upper-level support for the initiation of
boundary-layer based thunderstorm development is forecast to
generally remain north of the international border.

One exception may be in the post-frontal environment across eastern
Montana, the environment would be conducive to a few severe storms
capable of hail/wind. While the risk for severe thunderstorms
appears largely conditional into North Dakota where stronger
destabilization is expected, isolated deeper convective development
is plausible across northwestern North Dakota in proximity to the
surface low/front late this afternoon, and more so this evening.
Should this occur, forecast soundings indicate the environment would
support isolated supercell development and related severe-weather
risks.

..Guyer/Marsh.. 08/20/2025

$$

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ACUS01 KWNS 201630
SWODY1
SPC AC 201628

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
1128 AM CDT Wed Aug 20 2025

Valid 201630Z - 211200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
TEXAS INTO THE LOWER MISSISSIPPI VALLEY/SOUTHEAST...AND THE NORTHERN
PLAINS...

...SUMMARY...
Scattered thunderstorms from Texas across the Lower Mississippi
Valley and Southeast may pose a risk for localized damaging wind
gusts this afternoon and evening. Isolated severe thunderstorms may
also occur across parts of central/eastern Montana and northern
North Dakota, mainly this evening and overnight.

...Texas into the Lower Mississippi Valley and Southeast...
A convectively reinforced front/outflow boundary from
earlier/ongoing convection should once again provide a focus for
renewed convective development this afternoon from parts of
west-central TX eastward into the lower MS Valley and Southeast.
Mid-level flow and related deep-layer shear are expected to remain
weak, which should generally limit thunderstorm organization. Still,
a moderately to strongly unstable environment will exist along/south
of the front with continued daytime heating, with scattered to
numerous thunderstorms likely. Similar to yesterday, wet microbursts
from convective downdrafts may produce isolated damaging winds as
low-level lapse rates become steepened. These thunderstorms should
weaken through the evening with the loss of daytime heating.

...Northern Plains...
The northern Plains will be influenced by late-day/overnight
mid-level height falls as a shortwave trough moves eastward from the Canadian/northern Rockies, with a related cold front moving across central/eastern MT into ND tonight. A narrow corridor of moderate to
strong instability will likely develop along/ahead of the cold
front, and near a pre-frontal surface trough. But, warm mid-level
temperatures and a capped airmass will likely exist along/south of
the international border, which should inhibit robust convective
development for much of the day.

One exception may be in the post-frontal environment across eastern
MT this evening/tonight. The environment here should be conducive to
isolated severe thunderstorms capable of producing both large hail
and severe gusts. While the risk for severe thunderstorms appears
more conditional into ND where stronger destabilization is expected,
isolated convective development may still occur across northwestern
ND in proximity to the surface low/front late this afternoon, and
perhaps more so this evening/overnight. Should this occur, forecast
soundings indicate the environment would support isolated supercell
development with a related hail/wind threat.

..Gleason/Wendt.. 08/20/2025

$$

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ACUS01 KWNS 202000
SWODY1
SPC AC 201958

Day 1 Convective Outlook
NWS Storm Prediction Center Norman OK
0258 PM CDT Wed Aug 20 2025

Valid 202000Z - 211200Z

...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF
TEXAS INTO THE LOWER MISSISSIPPI VALLEY/SOUTHEAST...AND THE NORTHERN
PLAINS...

...SUMMARY...
Scattered thunderstorms from Texas across the Lower Mississippi
Valley and Southeast may pose a risk for localized damaging wind
gusts this afternoon and evening. Isolated severe thunderstorms may
also occur across parts of central/eastern Montana and northern
North Dakota, mainly this evening and overnight.

...20z Update...
Changes were made to clear the Marginal Risk across portions of
central Texas where thunderstorms and outflow have moved southward.

The Marginal Risk was expanded across the Southeast into portions of
northwest Georgia and eastern Alabama. A cluster of thunderstorms
continues to sag southward into this region, with cores exhibiting
some uptick in intensity. See MCD#1995.

Otherwise, the outlook remains on track with no additional changes
needed. See previous discussion below for more information.

..Thornton.. 08/20/2025

.PREV DISCUSSION... /ISSUED 1128 AM CDT Wed Aug 20 2025/

...Texas into the Lower Mississippi Valley and Southeast...
A convectively reinforced front/outflow boundary from
earlier/ongoing convection should once again provide a focus for
renewed convective development this afternoon from parts of
west-central TX eastward into the lower MS Valley and Southeast.
Mid-level flow and related deep-layer shear are expected to remain
weak, which should generally limit thunderstorm organization. Still,
a moderately to strongly unstable environment will exist along/south
of the front with continued daytime heating, with scattered to
numerous thunderstorms likely. Similar to yesterday, wet microbursts
from convective downdrafts may produce isolated damaging winds as
low-level lapse rates become steepened. These thunderstorms should
weaken through the evening with the loss of daytime heating.

...Northern Plains...
The northern Plains will be influenced by late-day/overnight
mid-level height falls as a shortwave trough moves eastward from the Canadian/northern Rockies, with a related cold front moving across central/eastern MT into ND tonight. A narrow corridor of moderate to
strong instability will likely develop along/ahead of the cold
front, and near a pre-frontal surface trough. But, warm mid-level
temperatures and a capped airmass will likely exist along/south of
the international border, which should inhibit robust convective
development for much of the day.

One exception may be in the post-frontal environment across eastern
MT this evening/tonight. The environment here should be conducive to
isolated severe thunderstorms capable of producing both large hail
and severe gusts. While the risk for severe thunderstorms appears
more conditional into ND where stronger destabilization is expected,
isolated convective development may still occur across northwestern
ND in proximity to the surface low/front late this afternoon, and
perhaps more so this evening/overnight. Should this occur, forecast
soundings indicate the environment would support isolated supercell
development with a related hail/wind threat.

$$

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