FOUS11 KWBC 310749
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
349 AM EDT Tue Mar 31 2026

Valid 12Z Tue Mar 31 2026 - 12Z Fri Apr 03 2026

...Potentially impactful mixed precipitation event increasingly
likely for the Upper Midwest into the Great Lakes Thursday...


...Sierra Nevada to the Rockies...
Days 1-2...

An incoming shortwave out of the Pacific this afternoon will bring
some light to perhaps modest snow to the Sierra Nevada, Wasatch,
Uintas, and CO Rockies as it zips eastward. To the north, lingering
moisture along a stationary surface boundary will maintain light
snow over the ID ranges into Wyoming with additional accumulation.
Snow levels will be high (8000-9000ft to the south, though falling
~1000ft as the trough moves through) with WPC probabilities for at
least 8 inches of snow are at least 50% above 7500ft (Sierra) to
10,000ft (CO). Totals in the CO Rockies may eclipses a foot above
11,000ft. Over ID into WY, WPC probabilities for at least 8 inches
of snow are at least 50% above 8000ft.


...Pacific Northwest to the Northern Rockies...
Days 2-3...

A powerful closed upper-low diving southward from the Gulf of
Alaska will be the catalyst for renewed mountain snow in the
Olympics, Cascades, the Salmon/Siskiyou of northern CA, and as far
east as the Blue Mountains Wednesday afternoon and continuing
through Thursday. The approaching 850-500mb layer heights
associated with the closed low are below the 10th percentile and
snow levels will be able to drop as low as 2,000ft Wednesday night
in the Olympics, Cascades, and even as far south as the Siskiyou. A
steady stream of Pacific moisture embedded within SWrly mean layer
flow, suitable for upslope enhancement as well, will also favor
locally heavy snowfall rates in these ranges. Drier air should move
in on the backside of the closed low by Thursday afternoon,
although lingering westerly low-level winds should support light-
to-moderate snow in the Cascades for the remainder of the day on
Thursday with all precipitation ending by early Friday morning west
of the Divide.

To the east, snow will start overnight tomorrow night and continue
through this forecast period (12Z Fri) over Montana. With a closed
low track from the WA/OR border ESE across central ID into central
WY, snow will maximize over the Blue Mountains, Bitterroots,
Absarokas, Tetons and into the Bighorns. The western MT ranges will
also see moderate snow totals closer to the 700mb low and old
triple point surface low.

WPC 48-hour probabilities for at least 12 inches of snow are high

70%) in the OR Cascades above 4,000ft with at least moderate

chances (>50%) for snowfall totals >8" at elevations >3,000ft. The
WA Cascades will see lesser snowfall totals than their OR neighbors
given the best Pacific moisture plume will reside farther south,
but several inches of snow at pass level (Snoqualmie and Stevens)
are expected. To the east, WPC probabilities for at least 12 inches
of snow are at least 50% above 7000ft or so.


...Northern New York and New England...
Days 1&3...

A lingering front will become the focus for organized
precipitation as a series of low-amplitude southern stream waves
interact with deepening moisture. Light precipitation will spread
across the region today with the first wave, followed by heavier
precipitation tonight as a following wave strengthens ahead of a
more amplified northern stream wave moving across Quebec. While
southwesterly flow aloft advects warmer air into the mid-levels, a
shallow but stubborn layer of sub-freezing air is expected to
remain entrenched across northern New England. Forecast soundings
support mostly snow across far northern Maine, while areas farther
south, including areas as far south as Downeast Maine, may see snow transitioning to accumulating ice. Guidance continues to indicate
that northwestern Maine is the area mostly likely to be impacted
with heavier ice accumulations. WPC probabilities of at least a
tenth of an inch of ice are 30-50% over the Central Highlands and
northern White Mountains. Northern Aroostook County has the highest
chance of staying all snow, with WPC probabilities of at least 4
inches 50-90%.

Following a brief dry period Wednesday night, the threat for
wintry weather is forecast to return to the region on Thursday as
the system detailed below lifts toward the Great Lakes -- bringing
moisture back into the region as cold high pressure remains
anchored to the north. For Day 3, the setup again would favor all
snow over far northern Maine then quickly transitioning to sleet
and freezing rain for the Central Highlands southwestward through
much of northern NH, the Northeast Kingdom of Vermont, and the
northern Adirondacks. WPC probabilities for at least 4 inches of
snow are 30-50% along the northern Maine border with Canada (North
Woods area). For freezing rain, WPC probabilities for at least a
tenth of an inch of ice are at least 30% over the northern CT River Valley/Northeast Kingdom into central/northern NH and northwestern
Maine.


...Upper Midwest/Corn Belt/Western Great Lakes...
Days 2-3...

An amplified shortwave exiting the Rockies Wednesday night will
lift toward the Great Lakes, directing a deep plume of Gulf
moisture to the north. As precipitation blossoms across the region
on Thursday, a sharp thermal gradient north of the I-80 corridor
will support a broad swath of wintry weather, topped by a west-
east band of heavy snow and bordered to the south by a corridor of
sleet and freezing rain, with significant ice accumulations
possible. Uncertainty remains high overall due to a shifting storm
track in the models (northwest trend since yesterday) and ptype
uncertainty through the storm evolution as many areas will see a
transition from snow or sleet to freezing rain and perhaps just
rain. Though precipitation may be still ongoing at the end of this
forecast period (12Z Fri), the heaviest will likely be on Thursday.

Through 12Z Friday, WPC probabilities for at least 4 inches of
snow are at least 50 percent from portions of the eastern Dakotas
through much of central to northeastern MN (especially the
Arrowhead), northern WI, and into the western U.P. of Michigan. The
highest probabilities of snowfall in excess of 8 inches lies over
the Arrowhead (30-60% chance).

The freezing rain may be significant within a broad region that
may see at least some icing; namely, SD through MN and WI to MI.
WPC probabilities for at least a tenth of an inch of ice are at
least 30% over much of Wisconsin into the U.P. and the northern 1/3
of Lower Michigan. Some areas could see in excess of 0.25" icing,
specifically central WI and northern Lower Michigan, but this is
subject to change with the storm track. The probability of Moderate
impacts per the WSSI-P are at least 40% in these areas.


Fracasso/Mullinax/Pereira



$$

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FOUS11 KWBC 311925
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
325 PM EDT Tue Mar 31 2026

Valid 00Z Wed Apr 01 2026 - 00Z Sat Apr 04 2026


...Northern Plains through the Great Lakes...
Days 1-3...

...Significant late season snow and freezing rain likely to create
substantial impacts through mid-week...

Late season winter storm will begin on Wednesday as a lee side low
pressure system develops across eastern Colorado. This low will
develop in response to a shortwave which will emerge from the
Pacific over California and then sharpen as it moves across the
Four Corners Wednesday. This shortwave is expected to then develop
a negative tilt as it pushes into the Upper Midwest Thursday before
exiting into Canada by Friday morning. The combination of
impressive downstream divergence ahead of this sharpening
shortwave, followed by height falls and the LFQ of a modest but
strengthening meridionally arcing jet streak will provide
widespread deep layer ascent to help deepen the surface low as it
tracks from Colorado northeast into Michigan.

The challenge for this period primarily revolves around the track
and timing of this low, as there is high confidence in its
development. Over the past 4 cycles of the ECENS and GEFS, the
surface low clusters have become more consolidated, but continue to
feature a subtle N/NW trend. This is in response to a small
deepening trend in the upper pattern, although the EC-AIFS has been exceptionally consistent with its track, so while the NW trend may
continue, it appears that is slowing and beginning to consolidate
leading to higher confidence overall.

As this low develops and tracks northeast, impressive moisture will
spread northward to support a large swath of all p-types. An
impressive IVT plume (>90% for 250 kg/m/s pushing well into the
Rockies) will support upper level moisture into the system, while
low-level moisture fueled by increasing WAA out of the Gulf help to
saturate the low-levels. The accompanying theta-e ridge emerging
northward will help expand the precipitation shield thanks to PW
anomalies that surge above the 99th percentile according to NAEFS.
This will result in periods of heavy precipitation, first across
the Dakotas Wednesday morning and then expanding eastward within
the WAA plume, reaching Michigan by Thursday morning, with
precipitation continuing through Thursday night, potentially
Friday morning across northern MN, before ending across the area.

In the locations that receive mostly snow, which is expected to be
the Dakotas, and the northern half of Minnesota, heavy
accumulations appear likely. In this area, snowfall rates of 1"/hr
appear likely through both WAA and then deformation on the NW side
of the low as it deepens, leading to 48-hr WPC probabilities that
are moderate (50-70%) for at least 4 inches of snow, with locally
more than 8 inches possible (10-30%) from the Buffalo Ridge through
the Arrowhead of MN and the western U.P. of MI. Lighter snowfall of
2-4" is likely south/east of this axis including the northern
suburbs of the Twin-Cities and Green Bay, where heavy snow will
develop but rapidly changeover to a mix and then rain, leading to
lesser snowfall.

The most substantial impacts from this event may be due to freezing
rain rather than ice. Although the Canadian high pressure over
Ontario will retreat quickly, antecedent wet-bulb temperatures are
well below freezing (in the low to mid 20s) due to very dry
dew point temperatures. Although these will slowly warm as the
impressive warm nose surges northward, there is likely to be an
extended period of freezing rain (after a period of snow and sleet)
from the IA/MN border northeast through much of WI and into the
northern L.P./eastern U.P. of MI. Exceptional WAA within the warm
nose, anomalous column moisture, and a lack of strong dry advection
to offset the latent heat release of freezing should limit the
freezing rain accretion efficiency. However, there is still likely
to be a long duration of freezing rain leading to significant and
impactful icing for which WPC probabilities indicate at least a 70%
chance of 0.1", with a 40-60% chance for at least 0.25" across WI.
Locally, more than 0.5" is possible (10-30% chance) in central WI
but at this time that appears to be more the exception than the
rule. Regardless, considerable impacts from icing are likely as
reflected by the WSSI-P which indicates a 60-80% chance for
moderate impacts.


...Sierra Nevada to the Central Rockies...
Days 1-3...

A shortwave trough is beginning to track into CA today and will
race east through the Great Basin tonight and over the central
Rockies by Wednesday. An impressive plume of Pacific moisture
(NAEFS shows IVT values of at least 99.5 climatological percentile
over the Southwest) will be directed at the Central Rockies with
periods of heavy mountain snow from the Wasatch on east through the
CO Rockies. Snow will be at its heaviest over the CO Rockies and
Wasatch tonight with lingering heavy snowfall continuing into
Wednesday. Snow rates will decrease by Wednesday night but some
lingering light mountain snow will continue. WPC probabilities show
high chances (>70%) for additional snowfall >6" in the central and
southern Sierra Nevada through Wednesday. The heaviest snowfall in
the Wasatch will occur above 8,000ft where as much as 6-12" of
snowfall is expected. The snowfall "jackpot" is in the CO Rockies
at/above 9,000ft where snowfall is likely to surpass 12" and may
approach 20" locally.

There is not much of a break in the snowfall as the next closed low
tracking through the Northwest directs yet another anomalous IVT
(200-300 kg/m/s, or above the 90th climatological percentile per
NAEFS) at CA and the Great Basin on Wednesday. Snow levels in the
northern CA ranges (Trinity, Siskiyou, Salmon) drop to as low as
3,000ft) with minor accumulations down to 3,000ft while heavier
totals (amounts surpassing 6") will generally be found at/above
5,000ft. Farther south, the northern Sierra Nevada above 6,000ft
have moderate-to-high chances (50-80%) for snowfall totals >6"
through Wednesday night. This same moisture source works its way
across the Wasatch, Uinta, and Bear River Ranges of UT, including
the southern WY and northern CO ranges by Thursday and lingering
through early Friday. WPC probabilities show moderate-to-high
chances (50-80%) for additional snowfall >8" in the listed UT
ranges with similar probabilities in the Park and Medicine Bow
ranges of WY/CO.

In summary, any significant impacts will be confined to the higher
elevations of these ranges, with one exception being I-80 and US-50 over
the Sierra Nevada where the the WSSI shows Moderate Impact
potential. Most of these mountain ranges east of the Sierra Nevada
are well below normal for cold season snowfall, so while some
travel impacts are possible, the snowfall is also welcomed with
the cold season now well into its "fourth quarter", so to speak.


...Pacific Northwest to the Northern Rockies...
Days 1-3...

A powerful closed upper-low diving southward from the Gulf of
Alaska will be the catalyst for renewed mountain snow in the
Olympics, Cascades, the Salmon/Siskiyou of northern CA, and as far
east as the Blue Mountains Wednesday afternoon and continuing
through Thursday. The approaching 850-500mb layer heights
associated with the closed low are below the 2.5 percentile per
NAEFS and snow levels will drop as low as 2,000ft Wednesday night
in the Olympics, Cascades, and even as far south as the Siskiyou. A
steady stream of Pacific moisture embedded within SWrly mean layer
flow, suitable for upslope enhancement as well, will also favor
locally heavy snowfall rates in these ranges. Drier air on the
backside of the closed low arrives Thursday afternoon, although
lingering westerly low-level winds should support light-to-
moderate snow in the Cascades for the remainder of the day on
Thursday. Precipitation tapers off east of the Divide by Thursday
night.

Farther east, snow will start Wednesday night and continue through
this forecast period (12Z Fri) over Montana. The closed low will
weaken to an extent, but it remains well intact as it moves east
with healthy upper-level divergence out ahead of the closed low.
In addition, NAEFS shows >90th climatological percentile levels
for 500mb and 700mb mean specific humidity (g/kg), indicating
unusually high moisture content higher up in the atmospheric
column. With a 500mb low track from the WA/OR border ESE across
central ID into central WY, snow will be heaviest on the low's
northern flank across the Blue Mountains, Bitterroots, Absarokas,
Tetons and into the Bighorns. The western MT ranges will also see
moderate snow totals closer to the 700mb low and added assist of
low-level easterly flow that results in upslope enhancement.

WPC 48-hour probabilities for at least 12 inches of snow are high

70%) in the OR Cascades above 4,000ft with at least moderate

chances (>50%) for snowfall totals >8" at elevations >3,000ft. The
WA Cascades will see lesser snowfall totals than their OR neighbors
given the best Pacific moisture plume will reside farther south,
but several inches of snow at pass level (Snoqualmie and Stevens)
are expected. To the east, WPC probabilities for at least 12 inches
of snow are moderate-to-high (50-70%) above 7000ft or so. The peaks
of the Blue, Sawtooth, Absaroka, and Tetons have low-to-moderate
odds (30-50%) for snowfall totals topping 18" through Friday.


...Northern New England...
Days 1 & 3...

A pair of sheared 500mb vorticity maxima tracking through northern
New England will be accompanied by a steady stream of 850-300mb
moisture aloft to produce periods of snow over far northern Maine
and a wintry mix of sleet/freezing rain in central Maine today and
tonight. As a wave of low pressure tracks along a warm front
draped over northern New England tonight, additional wintry
precipitation will develop and produce additional snow and ice
accumulations through Wednesday morning. WPC probabilities show at
least moderate chances (>50%) for additional snowfall totals over
4", while central Maine sports at least moderate chances (>50%) for
additional ice accumulations over one-tenth of an inch.

Following a break in the snow and ice Wednesday afternoon and
through much of the day on Thursday,moisture streaming north out
ahead of the Midwest winter storm will be paired with increasing
850-700mb WAA aloft that produces more precipitation. High pressure
over Quebec will help to lock in sub-freezign wet-bulb temps from
the White Mountains on north through interior Maine, allowing for
yet another round of wintry precipitation Thursday afternoon and
lingering through Thursday night. Snow will be the primary
precipitation at the onset in northern Maine, but even northern
Maine will flip over to a wintry mix Thursday night and continue to
contend with freezing rain into Friday morning. Eventually, strong
low-level WAA will erode the sub-freezing temperatures at the
surface and precipitation will changeover to plain rain. Prior to
the changeover to rain, WPC probabilities show low-to-moderate
chances (30-50%) for ice accumulations over one-tenth of an inch
over the White Mountains and along the Maine/Quebec border. Similar
are present for >4" of snowfall over far northern Maine through
Friday morning.

...Northern Plains...
Day 3...

No rest for the weary in the Northern Plains, as the departure of
one winter storm only means the arrival of yet another storm system
on Friday. A slow moving 500mb closed low over WY will generate
healthy PVA aloft and increased 700mb Q-vector convergence over the
northern High Plains. Snow will already be falling over central MT
and the Big Horns Thursday night, but as a surface low strengthens
along the KS/NE border Friday morning, 850-700mb WAA to the north
of the low will support banded precipitation on the northern flank
of the 500mb low. Guidance is in good agreement on the presence of
a very moist 700-300mb column, although exact placement of the
heaviest QPF axis is still unclear. Still, hazard-focused guidance
such as the ECMWF-EFI is showing a signal up to 0.8 for QPF from
the MT/WY border on east to SD. This product shows the potential
for an unusual amount of QPF at this storm's disposal, with thermal
profiles that do support snow on the storm's northern and western
flanks.

WPC probabilities show a large swath of at least moderate-chance
probabilities (>50%) for >4" of snow from northeast WY and southern
MT through northern SD and southern ND. Given the slow progression
of the upper low and likely banding associated with this storm,
snowfall rates >1"/hr for prolonged windows could result in
localized amounts exceeding 12". This is evident in WPC
probabilities that show low chances for >12" totals in northwest SD
and southwest ND. Lastly, there is the potential for some icing
closer to the warm front farther east. WPC probabilities show low-
to-moderate chances (30-50%) for ice accumulations over one-tenth
of an inch in southeast SD and southwest MN. Residents in the
Northern Plains should continue to monitor the forecast closely as
any subtle change in track or change in the storm's intensity could
mean notable changes to expected snowfall totals.


Mullinax/Weiss




$$

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FOUS11 KWBC 311926
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
326 PM EDT Tue Mar 31 2026

Valid 00Z Wed Apr 01 2026 - 00Z Sat Apr 04 2026


...Northern Plains through the Great Lakes...
Days 1-3...

...Significant late season snow and freezing rain likely to create
substantial impacts through mid-week...

Late season winter storm will begin on Wednesday as a lee side low
pressure system develops across eastern Colorado. This low will
develop in response to a shortwave which will emerge from the
Pacific over California and then sharpen as it moves across the
Four Corners Wednesday. This shortwave is expected to then develop
a negative tilt as it pushes into the Upper Midwest Thursday before
exiting into Canada by Friday morning. The combination of
impressive downstream divergence ahead of this sharpening
shortwave, followed by height falls and the LFQ of a modest but
strengthening meridionally arcing jet streak will provide
widespread deep layer ascent to help deepen the surface low as it
tracks from Colorado northeast into Michigan.

The challenge for this period primarily revolves around the track
and timing of this low, as there is high confidence in its
development. Over the past 4 cycles of the ECENS and GEFS, the
surface low clusters have become more consolidated, but continue to
feature a subtle N/NW trend. This is in response to a small
deepening trend in the upper pattern, although the EC-AIFS has been exceptionally consistent with its track, so while the NW trend may
continue, it appears that is slowing and beginning to consolidate
leading to higher confidence overall.

As this low develops and tracks northeast, impressive moisture will
spread northward to support a large swath of all p-types. An
impressive IVT plume (>90% for 250 kg/m/s pushing well into the
Rockies) will support upper level moisture into the system, while
low-level moisture fueled by increasing WAA out of the Gulf help to
saturate the low-levels. The accompanying theta-e ridge emerging
northward will help expand the precipitation shield thanks to PW
anomalies that surge above the 99th percentile according to NAEFS.
This will result in periods of heavy precipitation, first across
the Dakotas Wednesday morning and then expanding eastward within=20
the WAA plume, reaching Michigan by Thursday morning, with
precipitation continuing through Thursday night, potentially
Friday morning across northern MN, before ending across the area.

In the locations that receive mostly snow, which is expected to be
the Dakotas, and the northern half of Minnesota, heavy
accumulations appear likely. In this area, snowfall rates of 1"/hr
appear likely through both WAA and then deformation on the NW side
of the low as it deepens, leading to 48-hr WPC probabilities that=20
are moderate (50-70%) for at least 4 inches of snow, with locally
more than 8 inches possible (10-30%) from the Buffalo Ridge through
the Arrowhead of MN and the western U.P. of MI. Lighter snowfall of
2-4" is likely south/east of this axis including the northern
suburbs of the Twin-Cities and Green Bay, where heavy snow will
develop but rapidly changeover to a mix and then rain, leading to
lesser snowfall.

The most substantial impacts from this event may be due to freezing
rain rather than ice. Although the Canadian high pressure over
Ontario will retreat quickly, antecedent wet-bulb temperatures are
well below freezing (in the low to mid 20s) due to very dry
dew point temperatures. Although these will slowly warm as the
impressive warm nose surges northward, there is likely to be an
extended period of freezing rain (after a period of snow and sleet)
from the IA/MN border northeast through much of WI and into the
northern L.P./eastern U.P. of MI. Exceptional WAA within the warm
nose, anomalous column moisture, and a lack of strong dry advection
to offset the latent heat release of freezing should limit the
freezing rain accretion efficiency. However, there is still likely
to be a long duration of freezing rain leading to significant and
impactful icing for which WPC probabilities indicate at least a 70%
chance of 0.1", with a 40-60% chance for at least 0.25" across WI.=20
Locally, more than 0.5" is possible (10-30% chance) in central WI=20
but at this time that appears to be more the exception than the=20
rule. Regardless, considerable impacts from icing are likely as=20
reflected by the WSSI-P which indicates a 60-80% chance for=20
moderate impacts.

Key Messages for this winter storm have been initiated. A link to
view the Key Messages are below.=20


...Sierra Nevada to the Central Rockies...
Days 1-3...

A shortwave trough is beginning to track into CA today and will
race east through the Great Basin tonight and over the central=20
Rockies by Wednesday. An impressive plume of Pacific moisture
(NAEFS shows IVT values of at least 99.5 climatological percentile
over the Southwest) will be directed at the Central Rockies with
periods of heavy mountain snow from the Wasatch on east through the
CO Rockies. Snow will be at its heaviest over the CO Rockies and
Wasatch tonight with lingering heavy snowfall continuing into
Wednesday. Snow rates will decrease by Wednesday night but some=20
lingering light mountain snow will continue. WPC probabilities show
high chances (>70%) for additional snowfall >6" in the central and
southern Sierra Nevada through Wednesday. The heaviest snowfall in
the Wasatch will occur above 8,000ft where as much as 6-12" of
snowfall is expected. The snowfall "jackpot" is in the CO Rockies
at/above 9,000ft where snowfall is likely to surpass 12" and may
approach 20" locally.=20

There is not much of a break in the snowfall as the next closed low
tracking through the Northwest directs yet another anomalous IVT
(200-300 kg/m/s, or above the 90th climatological percentile per
NAEFS) at CA and the Great Basin on Wednesday. Snow levels in the
northern CA ranges (Trinity, Siskiyou, Salmon) drop to as low as
3,000ft) with minor accumulations down to 3,000ft while heavier
totals (amounts surpassing 6") will generally be found at/above
5,000ft. Farther south, the northern Sierra Nevada above 6,000ft
have moderate-to-high chances (50-80%) for snowfall totals >6"
through Wednesday night. This same moisture source works its way
across the Wasatch, Uinta, and Bear River Ranges of UT, including
the southern WY and northern CO ranges by Thursday and lingering
through early Friday. WPC probabilities show moderate-to-high
chances (50-80%) for additional snowfall >8" in the listed UT
ranges with similar probabilities in the Park and Medicine Bow=20
ranges of WY/CO.=20

In summary, any significant impacts will be confined to the higher
elevations of these ranges, with one exception being I-80 and US-50 over
the Sierra Nevada where the the WSSI shows Moderate Impact
potential. Most of these mountain ranges east of the Sierra Nevada
are well below normal for cold season snowfall, so while some
travel impacts are possible, the snowfall is also welcomed with=20
the cold season now well into its "fourth quarter", so to speak.=20


...Pacific Northwest to the Northern Rockies...
Days 1-3...

A powerful closed upper-low diving southward from the Gulf of=20
Alaska will be the catalyst for renewed mountain snow in the=20
Olympics, Cascades, the Salmon/Siskiyou of northern CA, and as far=20
east as the Blue Mountains Wednesday afternoon and continuing=20
through Thursday. The approaching 850-500mb layer heights=20
associated with the closed low are below the 2.5 percentile per
NAEFS and snow levels will drop as low as 2,000ft Wednesday night=20
in the Olympics, Cascades, and even as far south as the Siskiyou. A
steady stream of Pacific moisture embedded within SWrly mean layer
flow, suitable for upslope enhancement as well, will also favor=20
locally heavy snowfall rates in these ranges. Drier air on the=20
backside of the closed low arrives Thursday afternoon, although=20
lingering westerly low-level winds should support light-to-=20
moderate snow in the Cascades for the remainder of the day on=20
Thursday. Precipitation tapers off east of the Divide by Thursday
night.

Farther east, snow will start Wednesday night and continue through
this forecast period (12Z Fri) over Montana. The closed low will
weaken to an extent, but it remains well intact as it moves east
with healthy upper-level divergence out ahead of the closed low.
In addition, NAEFS shows >90th climatological percentile levels
for 500mb and 700mb mean specific humidity (g/kg), indicating
unusually high moisture content higher up in the atmospheric
column. With a 500mb low track from the WA/OR border ESE across=20
central ID into central WY, snow will be heaviest on the low's
northern flank across the Blue Mountains, Bitterroots, Absarokas,=20
Tetons and into the Bighorns. The western MT ranges will also see=20
moderate snow totals closer to the 700mb low and added assist of
low-level easterly flow that results in upslope enhancement.

WPC 48-hour probabilities for at least 12 inches of snow are high=20

70%) in the OR Cascades above 4,000ft with at least moderate=20

chances (>50%) for snowfall totals >8" at elevations >3,000ft. The=20
WA Cascades will see lesser snowfall totals than their OR neighbors
given the best Pacific moisture plume will reside farther south,=20
but several inches of snow at pass level (Snoqualmie and Stevens)=20
are expected. To the east, WPC probabilities for at least 12 inches
of snow are moderate-to-high (50-70%) above 7000ft or so. The peaks
of the Blue, Sawtooth, Absaroka, and Tetons have low-to-moderate
odds (30-50%) for snowfall totals topping 18" through Friday.


...Northern New England...
Days 1 & 3...

A pair of sheared 500mb vorticity maxima tracking through northern
New England will be accompanied by a steady stream of 850-300mb=20
moisture aloft to produce periods of snow over far northern Maine=20
and a wintry mix of sleet/freezing rain in central Maine today and=20
tonight. As a wave of low pressure tracks along a warm front
draped over northern New England tonight, additional wintry
precipitation will develop and produce additional snow and ice
accumulations through Wednesday morning. WPC probabilities show at
least moderate chances (>50%) for additional snowfall totals over
4", while central Maine sports at least moderate chances (>50%) for
additional ice accumulations over one-tenth of an inch.

Following a break in the snow and ice Wednesday afternoon and
through much of the day on Thursday,moisture streaming north out=20
ahead of the Midwest winter storm will be paired with increasing=20
850-700mb WAA aloft that produces more precipitation. High pressure
over Quebec will help to lock in sub-freezign wet-bulb temps from
the White Mountains on north through interior Maine, allowing for
yet another round of wintry precipitation Thursday afternoon and
lingering through Thursday night. Snow will be the primary
precipitation at the onset in northern Maine, but even northern
Maine will flip over to a wintry mix Thursday night and continue to
contend with freezing rain into Friday morning. Eventually, strong
low-level WAA will erode the sub-freezing temperatures at the=20
surface and precipitation will changeover to plain rain. Prior to
the changeover to rain, WPC probabilities show low-to-moderate
chances (30-50%) for ice accumulations over one-tenth of an inch
over the White Mountains and along the Maine/Quebec border. Similar
are present for >4" of snowfall over far northern Maine through=20
Friday morning.=20

...Northern Plains...
Day 3...

No rest for the weary in the Northern Plains, as the departure of
one winter storm only means the arrival of yet another storm system
on Friday. A slow moving 500mb closed low over WY will generate
healthy PVA aloft and increased 700mb Q-vector convergence over the
northern High Plains. Snow will already be falling over central MT
and the Big Horns Thursday night, but as a surface low strengthens
along the KS/NE border Friday morning, 850-700mb WAA to the north
of the low will support banded precipitation on the northern flank
of the 500mb low. Guidance is in good agreement on the presence of
a very moist 700-300mb column, although exact placement of the
heaviest QPF axis is still unclear. Still, hazard-focused guidance
such as the ECMWF-EFI is showing a signal up to 0.8 for QPF from
the MT/WY border on east to SD. This product shows the potential
for an unusual amount of QPF at this storm's disposal, with thermal
profiles that do support snow on the storm's northern and western
flanks.

WPC probabilities show a large swath of at least moderate-chance
probabilities (>50%) for >4" of snow from northeast WY and southern
MT through northern SD and southern ND. Given the slow progression
of the upper low and likely banding associated with this storm,
snowfall rates >1"/hr for prolonged windows could result in
localized amounts exceeding 12". This is evident in WPC
probabilities that show low chances for >12" totals in northwest SD
and southwest ND. Lastly, there is the potential for some icing
closer to the warm front farther east. WPC probabilities show low-
to-moderate chances (30-50%) for ice accumulations over one-tenth
of an inch in southeast SD and southwest MN. Residents in the=20
Northern Plains should continue to monitor the forecast closely as=20
any subtle change in track or change in the storm's intensity could
mean notable changes to expected snowfall totals.=20


Mullinax/Weiss



...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!9LLptld8EifLcDw_r2bJ3bvA7Ix7k7UFGRS-52nXqJM6H= 29OpvGj5Pog1zl0CyJJt8GyvWsRhe_vxt0JlHmd3rExL5I$=20



$$

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FOUS11 KWBC 010826
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
426 AM EDT Wed Apr 1 2026

Valid 12Z Wed Apr 01 2026 - 12Z Sat Apr 04 2026


...Northern Plains through the Great Lakes...
Days 1-2...

...Significant late-season snow and freezing rain likely to create
substantial impacts...

Late-season winter storm will begin tonight as an exiting=20
shortwave out of the Rockies spurs a lee-side low pressure system=20
this afternoon. This shortwave is expected to then develop a=20
negative tilt as it pushes into the Upper Midwest Thursday before=20
exiting into Canada by Friday morning. The combination of=20
impressive downstream divergence ahead of this sharpening shortwave
followed by height falls and the LFQ of a modest but strengthening
meridionally arcing jet streak will provide widespread deep-layer=20
ascent to help strengthen the surface low as it tracks from=20
Colorado northeastward into Michigan.

Impressive moisture will spread northward to support a large swath
of all p-types that move through time during the event. Ample=20
upper-level moisture from the southwest and low-level moisture=20
fueled by increasing WAA out of the Gulf will saturate the low=20
levels. The accompanying theta-e ridge emerging northward will help
expand the precipitation shield thanks to PW anomalies that surge=20
above the 99th percentile according to NAEFS. This will result in=20
periods of heavy precipitation, first across the Dakotas this=20
morning and then expanding eastward within the WAA plume, reaching=20
Michigan by Thursday morning. Precipitation will continue through=20
Thursday night and eventually end from southwest to northeast on=20
Friday morning.

In the locations that receive mostly snow, which is expected to be
mostly in the northern half of Minnesota, modest to locally heavy=20 accumulations appear likely. In this area, snowfall rates of 1"/hr=20
are likely via deformation on the NW side of the low as it deepens,
leading to 48-hr WPC probabilities that are moderate/high (50-80%)
for at least 4 inches of snow, with locally more than 8 inches=20
possible (10-30%) from the Buffalo Ridge through the Arrowhead of=20
MN (40-60%) and into the Keweenaw Peninsula. Lighter snowfall of=20
2-4" is likely south/east of this axis north of the Twin-Cities and
Green Bay. In these regions, heavy snow will develop but rapidly=20
change over to a wintry mix and then rain, leading to lesser=20
snowfall.

The most substantial impacts from this event may be due to=20
freezing rain. Although the Canadian high pressure over Ontario=20
will retreat quickly, antecedent wet-bulb temperatures are well=20
below freezing (in the low to mid 20s this morning) due to very dry
dew point temperatures. Although these will slowly warm as the=20
impressive warm nose surges northward, there is likely to be an=20
extended period of freezing rain (after a period of snow and sleet)
from the eastern SD and along/north of the IA/MN border through=20
much of WI and into the northern L.P./eastern U.P. of MI.=20
Exceptional WAA within the warm nose, anomalous column moisture,=20
and a lack of strong dry advection to offset the latent heat=20
release of freezing should limit the freezing rain accretion=20
efficiency. However, there is still likely to be a long duration of
freezing rain leading to significant and impactful icing for which
WPC probabilities indicate at least a 70% chance of 0.1", with a=20
40-70% chance for at least 0.25" across WI. Locally, more than 0.5"
is possible (10-40% chance) in central WI. Considerable impacts=20
from icing are likely as reflected by the WSSI that shows=20
widespread moderate to locally major impacts.=20

Please see a link to view the Key Messages at the end of this=20
discussion.



...CA/Great Basin to the Central Rockies...
Days 1-2...

A shortwave trough over the Great Basin this morning will continue
eastward today. An impressive plume of Pacific moisture (NAEFS=20
shows IVT values of at least 99.5 climatological percentile over=20
the Southwest) will be directed at the Central Rockies with periods
of heavy mountain snow from the Wasatch on east through the CO=20
Rockies. Snow will wane from west to east today over NV/UT but=20
continue over the CO Rockies through the day and diminishing=20
overnight. WPC probabilities for an additional 6 inches of snow are

50% over the Wasatch and Uintas. Over the CO Rockies, WPC=20

probabilities for at least an additional 12 inches of snow are >50%
above 10,000ft.=20

There is not much of a break in the snowfall as the next closed=20
low tracking through the Northwest directs yet another anomalous=20
IVT (200-300 kg/m/s, or above the 90th climatological percentile=20
per NAEFS) at CA and the Great Basin starting later today. Snow=20
levels in the northern CA ranges (Trinity, Siskiyou, Salmon) drop=20
to as low as 3,000ft with minor accumulations. Heavier totals=20
(amounts surpassing 6") will generally be found at/above 5,000ft.=20
Farther south, the northern Sierra Nevada above 6,000ft have=20 moderate-to-high chances (50-80%) for snowfall totals >6" through=20
tomorrow morning. This same moisture source works its way across=20
the Wasatch, Uinta, and Bear River Ranges of UT, including the=20
southern WY and northern CO ranges by Thursday and lingering=20
through early Friday. WPC probabilities show moderate-to- high=20
chances (50-80%) for additional snowfall >8" in the listed UT=20
ranges with similar probabilities in the Park and Medicine Bow=20
ranges of WY/CO.=20

In summary, any significant impacts will be confined to the higher
elevations of these ranges, with one exception being I-80 and=20
US-50 over the Sierra Nevada where the the WSSI shows Moderate=20
Impact potential. Most of these mountain ranges east of the Sierra=20
Nevada are well below normal for cold season snowfall, so while=20
some travel impacts are possible, the snowfall is also welcomed=20
with the cold season trying to make up for lost time.=20


...Pacific Northwest to the Northern Rockies...
Days 1-2...

A powerful closed upper-low diving southward from the Gulf of=20
Alaska will be the catalyst for renewed mountain snow in the=20
Olympics, Cascades, the Salmon/Siskiyou of northern CA, and as far=20
east as the Blue Mountains this afternoon and continuing through=20
Thursday. The approaching 850-500mb layer heights associated with=20
the closed low are below the 2.5 percentile per NAEFS and snow=20
levels will drop as low as 2,000ft Wednesday night in the Olympics,
Cascades, and even as far south as the Siskiyou. A steady stream=20
of Pacific moisture embedded within SWrly mean layer flow, suitable
for upslope enhancement as well, will also favor locally heavy=20
snowfall rates in these ranges. Drier air on the backside of the=20
closed low arrives Thursday afternoon, although lingering westerly=20
low-level winds should support light-to-moderate snow in the=20
Cascades for the remainder of the day on Thursday. Precipitation=20
tapers off east of the Divide by Thursday night.

Farther east, snow will start tonight and continue through Friday=20
over Montana. The closed low will weaken to an extent, but it=20
remains well intact as it moves east with healthy upper-level=20
divergence out ahead of the closed low. In addition, NAEFS shows=20

90th climatological percentile levels for 500mb and 700mb mean=20

specific humidity (g/kg), indicating unusually high moisture=20
content higher up in the atmospheric column. With a 500mb low track
from the WA/OR border ESE across central ID into central WY, snow=20
will be heaviest on the low's northern flank across the Blue=20
Mountains, Bitterroots, Absarokas, Tetons and into the Bighorns.=20
The western MT ranges will also see moderate snow totals closer to=20
the 700mb low and added assist of low-level easterly flow that=20
results in upslope enhancement.

WPC 48-hour probabilities for at least 12 inches of snow are high=20

70%) in the OR Cascades above 4,000ft with at least moderate=20

chances (>50%) for snowfall totals >8" at elevations >3,000ft. The=20
WA Cascades will see lesser snowfall totals than their OR neighbors
given the best Pacific moisture plume will reside farther south,=20
but several inches of snow at pass level (Snoqualmie and Stevens)=20
are expected. To the east, WPC probabilities for at least 12 inches
of snow are moderate-to-high (50-70%) above 7000ft or so. The=20
peaks of the Blue, Sawtooth, Absaroka, and Tetons have low-to-
moderate chances (30-50%) for snowfall totals in excess of 18"=20
through Friday.


...Northern New England...
Day 2...

Moisture streaming north out ahead of the Midwest winter storm=20
will be paired with increasing 850-700mb WAA aloft that produces=20
another round of precipitation. High pressure over Quebec will help
to lock in sub-freezign wet bulb temps from the White Mountains=20
northward through interior Maine, allowing for yet another mixed=20
wintry precipitation Thursday afternoon and lingering through=20
Thursday night. Snow will be the primary precipitation at the onset
in northern Maine, but even there it will flip over to a wintry=20
mix Thursday night with both sleet and freezing rain into Friday=20
morning. Eventually, strong low-level WAA will erode the sub-
freezing temperatures at the surface and precipitation will change=20
over to plain rain late Friday before ending overnight. Prior to=20
the changeover to rain, WPC probabilities for at least a tenth of=20
an inch of ice are moderate (40-60%) over the White Mountains and=20
along the northwestern Maine/Quebec border. Snow will really be=20
limited to just the Allagash where WPC probabilities for at least 4
inches are 20-40%.=20


...Northern Plains to the Upper Midwest...
Day 2.5-3...

The relatively progressive pattern across the CONUS will introduce
another round of potentially impactful snow to the Northern Plains
to the Upper Midwest Friday into Saturday. A slower moving 500mb=20
closed low over WY will generate healthy PVA aloft and increased=20
700mb Q-vector convergence over the northern High Plains early=20
Friday. Snow will already be falling over central MT and the Big=20
Horns Thursday night, but as a surface low strengthens along the=20
KS/NE border Friday morning, 850-700mb WAA to the north of the low=20
will support banded precipitation on the northern flank of the=20
500mb low. Guidance is in good agreement on the presence of a very=20
moist 700-300mb column, although exact placement of the heaviest=20
QPF axis is still unclear. The area of low pressure will track=20
northeastward through Iowa and cross into WI by the end of this=20
forecast period (12Z Sat), though there is spread in the speed of=20
the low. Snow will remain on the northwest side of the low over the
Dakotas to northern MN but an area of mixed precip (sleet/freezing
rain) is again likely over parts of southern MN into WI and the=20
U.P. of Michigan.=20

WPC probabilities show a large swath of at >50% probability for at
least 4 inches of snow from northeast WY and southern/southeastern
MT through northern SD and southern ND east-northeastward to=20
northern MN. Given the slower progression of the upper low and=20
likely banding associated with this storm, snowfall rates >1"/hr=20
for a prolonged period could result in localized amounts exceeding=20
12" -- WPC probabilities show 20-40% chances in southern ND into=20
northern SD. Farther east, WPC probabilities for at least a tenth=20
of an inch of ice are 10-40% over southeast SD/southwest MN but=20
40-60% over northern WI into the U.P. of Michigan where most of the precipitation will fall overnight Friday into early Saturday.=20
Changes to the forecast are likely but this system will likely have
impacts for much of the region, especially those who see a wintry=20
mix from the prior system later today/Thursday.=20


Fracasso/Mullinax/Weiss



...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!7LXNvgEotodsiPtRLncNZZFH7w0ysb5ByUQIYWixIQ6yv= -LQ6D73B2VQP6jitBqGvh-v6DyvnioWBSFVeEppxkkRe5Q$=20



$$

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--- SBBSecho 3.28-Linux
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FOUS11 KWBC 012006
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
406 PM EDT Wed Apr 1 2026

Valid 00Z Thu Apr 02 2026 - 00Z Sun Apr 05 2026


...Northern Plains through the Great Lakes...
Days 1-2...

...Significant late-season snow and freezing rain likely to create
substantial impacts...

Significant winter storm begins tonight as a low pressure develops
in the lee of the Colorado Rockies and then tracks northeast into
the Upper Midwest and Great Lakes, reaching Ontario Friday
afternoon. This system is driven by a shortwave that will be moving
atop the Central Rockies Thursday morning and amplify into a
negatively tilted trough as it lifts northeast into Ontario by
Friday. The trends in the guidance have been for this shortwave to
be a bit deeper, leading to sharper height falls combined with the
LFQ of a modest but meridionally arcing jet streak. This will
produce significant deep layer ascent to deepen the surface low as
it tracks northeast, and the guidance has clustered to a slightly
slower but stronger surface low today.

As this low tracks northeast, impressive column PW will manifest=20
across the Upper Midwest in response to dual moisture streams
interacting into the region. Residual IVT from the Pacific will
continue to push inland with the shortwave over the Rockies, and
IVT probabilities for >250 kg/m/s remain high, bringing elevated
moisture into the region on the 700-500mb flow. In the lower
levels, return flow out of the Gulf begins to intensify as 850mb=20
winds surge northward, spreading a pronounced theta-e ridge
northward into the system. The overlap of these two moisture
streams will create PW anomalies that are above the 99th percentile
of the CFSR climatology according to NAEFS, and this is likely to
be a very wet early-spring system.=20

The primary driver of the associated precipitation will be
intensifying isentropic ascent, especially along the 290-295K
surfaces where mixing ratios of 4-5 g/kg will support heavy
precipitation anywhere within the system. The strongest ascent will
be where the 850mb winds and accompanying WAA produce intense fgen,
and this will result in an above-freezing warm nose surging
northward. The surface high pressure responsible for the cold/dry
antecedent airmass will retreat rapidly to the northeast, and=20
regional soundings indicate that a lack of sufficient dry-bulb=20
advection will promote a rapid transition from snow to freezing=20
rain, especially for eastern MN through MI, with snow remaining the
primary p-type for northern MN and the eastern Dakotas.

In the snow areas, heavy snow rates will develop as fgen=20
strengthens and then a modest deformation axis develops to drive=20
ascent into the modest TROWAL which will form as the theta-e ridge=20
wraps cyclonically into the system. With elevated PWs in place,=20
this should result in rates approaching 1"/hr at times as supported
by the WPC prototype snowband tool, and any local banding will
enhance the duration of snowfall. Overall snowfall amounts will be
modest due to the rapid progression of this system, but a slightly
slower track and some heavier snowfall rates will still support a
high risk (>70% chance) for more than 4 inches of snow from eastern
ND through northern MN and the Arrowhead, with locally as much as 8
inches possible (10-30% chance) across this same axis.

Farther east, the primary p-type will likely be freezing rain as
the warm air aloft floods northward without any strong forcing to
prevent this. The cold layer beneath the warm nose is quite deep,
above the 75th% for cold-layer depth for freezing rain, so there
may be some considerable sleet before changeover to freezing rain,
with 0.5" to 1.0" of sleet possible for northern WI and the U.P.=20
of MI. However, the greatest impacts are likely from the Buffalo=20
Ridge through the Twin Cities, into central WI, and the northern=20
L.P. of MI where WPC probabilities indicate a moderate to high risk
(50-90% chance) of at least 0.1" of ice, with 0.25" or even 0.5"=20
possible (50% and 20% respectively) across parts of WI.

Key Messages are in effect for this system and are linked below
(Key Messages #1).


...Northern New England...
Day 2...

Moisture streaming northward ahead of the large Midwest winter
storm will surge into New England Thursday night and Friday on
persistent warm advection. As the WAA intensifies through the
850-700mb layer, precipitation will expand from Vermont into Maine
in response to the maximizing fgen. During precipitation onset,
wet-bulb temperatures will be below freezing (with a full below-
freezing column across Maine) as Canadian high pressure only slowly
retreats to the northeast. As this high retreats and the WAA
continues, the accompanying warm nose should surge all the way into
Canada causing a p-type transition from snow to sleet to freezing
rain, and eventually rain. Before the changeover, a period of heavy
snow with rates around 1"/hr are possible, primarily just for
northern Maine, leading to WPC probabilities that are 50-70% for at
least 4 inches of snowfall. Farther south, from the White Mountains
of NH into the higher terrain of northern/central ME, a period of
freezing rain is expected which will lead to a moderate risk
(30-50% chance) of at least 0.1" of ice accumulation. Although the
snowfall by itself, or the icing by itself, may not result directly in warning-level impacts, the combination of a period of heavy snow,
followed by sleet, followed by freezing rain, will create
treacherous travel and some elevated snow load on trees/wires
leading to substantial impacts across parts of northern ME.

While the heaviest snow and ice are expected only in the higher=20
terrain or highest latitudes of northern New England, light snow=20 accumulations and light icing is expected for much of northern and=20
central New England before p-type transitions to all rain by late=20
Friday morning.


...Pacific Northwest/Sierra through Northern/Central Rockies...=20
Days 1-2...

Active winter weather continues through late-week as an anomalously
deep trough digs across the Northwest bringing widespread heavy
snow to the terrain through Friday.

At the beginning of the period /00Z Thursday/ a shortwave will be
positioned off the WA coast, with impressive confluent flow to its
south driving moisture onshore as reflected by IVT probabilities
for at least 250 kg/m/s exceeding 90% from the GEFS/ECENS lifting
into WA/OR D1. This shortwave is progged to amplify into a potent
closed low and dig into the Pacific and Interior Northwest by
Thursday morning, and then continue to move slowly but steadily
eastward with impressive height falls reaching the Northern and
Central Rockies by Friday morning. This feature will be expansive
and amplified, reflected by a large swath of 500mb heights falling
below the 10th percentile within the CFSR climatology according to
NAEFS.=20

As this closed low dives E/SE through the area, the accompanying
Pacific jet streak (which will be weakening from 140 kts early D1
to 110 kts late D1) will continue to be favorably positioned to
enhance deep layer lift through its diffluent LFQ, resulting in
sufficient ventilation for surface low development tracking from WA
to WY by early D2. This low will also drag a strong cold front
behind it, bringing colder temperatures and lowering snow levels
through the event.

With significant deep layer ascent in place, and moisture
increasing through the onshore flow from the Pacific, precipitation
is expected to be widespread Thursday into Friday. Initially, snow
levels are expected to be between 6000-8000 ft ahead of the cold
front, but will fall sharply as it tracks southeast, dropping to as
low as 2500-3000 ft across much of the region. It appears that the
heaviest precipitation will occur along and ahead of this front, so
the heaviest snowfall should remain at the mid-to-higher
elevations. However, some light snow is expected down to many of
the passes as the cold front progresses eastward, leading to
widespread hazardous travel before precipitation wanes Friday
morning.

On D1 /00Z Thu to 00Z Fri/ WPC probabilities indicate the highest
snowfall potential will be across the northern Sierra and Oregon
Cascades where the moisture will be directed orthogonally into the
terrain, leading to upslope enhancement, with additional
significant spillover leading to heavy snow as well into the=20
Salmon River/Sawtooth Ranges, and the Tetons/Wind Rivers. In these=20
areas, WPC probabilities are high (>70%) for at least 8 inches of=20
snow, with locally 12-18" possible in the highest terrain.=20
Elsewhere on D1, WPC probabilities suggest a high risk for at least
4 inches for the WA Cascades, much of the Northern Rockies, and=20
surrounding terrain as far south as the Ruby Mountains of NV,=20
Uintas of UT, and even into the Park Range and portions of the CO=20
Rockies.

By D2, the focus of heaviest snow shifts well to the interior,
leaving heavy snow only across the Northern and Central Rockies as
a significant lee cyclone develops across WY (more on this in the
section below). Additional snowfall D2 has a high risk (>70%
chance) of at least 6 inches across the Absarokas and Big Horns,
with lower probabilities extending into the Little Belts, Lewis
Range, and portions of the CO Rockies and Laramie range. The
heaviest snowfall D2 should be above 4000 ft.


...Northern Plains to the Upper Midwest...
Day 2.5-3...

...Significant late-season snow and freezing rain likely to create
substantial impacts...

A slow moving 500mb closed low over WY will generate healthy PVA=20
aloft and increased 700mb Q-vector convergence over the northern=20
High Plains on Friday. Snow will already be falling over central=20
MT and the Big Horns Thursday night, but as a surface low=20
strengthens along the KS/NE border Friday morning, 850-700mb WAA to
the north of the low will support banded precipitation on the=20
northern flank of the 500mb low. Guidance is in good agreement on=20
the presence of a very moist 700-300mb column with strong vertical
velocities aloft supporting snowfall rates of 1-2"/hr. On the=20
eastern flank of the storm, freezing rain and sleet will be more=20
prominent from central MN on north and east into northern WI and=20
the U.P. of MI. Snow will persist over northern MN into Saturday
with any ongoing ice changing over to snow in northern WI and the
western U.P. of MI. Cyclonic flow on the back side of the storm
will keep periods of snow in the forecast across the U.P. of MI
through early Sunday morning.=20

WPC probabilities show a large swath of at >50% probability for at
least 8 inches of snow from southern ND and norther SD on east into
northern MN. Where the pivoting deformation zone forms in southern
ND and northern SD sets up will determine who sees the most snow.
WPC probabilities show moderate chances (40-60%) for >12" of snow
in south-central ND and north-central SD at this time. In fact,
there are low chance probabilities (10-30%) for localized amounts
surpassing 18". Farther east, WPC probabilities for at least a=20
tenth of an inch of ice show moderate chances (40-60%) over=20
southeast SD/southwest MN but high chances (>70) over northern WI=20
and the U.P. of MI.. It is in northern WI and the U.P. of MI where
there are concerns for prolonged affects between the two winter
storms late week, given WPC probabilities show at least moderate
chances (>50%) for additional ice accumulations over one-quarter
inch. The Day 3 WSSI currently shows Moderate Impacts in southern=20
ND and northern SD due to the heavy snowfall, as well as in
northern WI and the U.P. of Michigan due to ice accumulations.


Weiss/Mullinax




...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!6kBIVWskrvb06emiItPe0iWe3MYfSSYFjc26_7QOJyA5S= 3uBhNh0vi7LP9MuEdmRbLblHu2pDu2m_865te55uqGdjmQ$=20

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!6kBIVWskrvb06emiItPe0iWe3MYfSSYFjc26_7QOJyA5S= 3uBhNh0vi7LP9MuEdmRbLblHu2pDu2m_865te55qkvw7og$=20



$$

=3D =3D =3D
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FOUS11 KWBC 020730
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
330 AM EDT Thu Apr 2 2026

Valid 12Z Thu Apr 02 2026 - 12Z Sun Apr 05 2026


...Northern Plains through the Great Lakes...
Day 1...

...First of back-to-back systems will bring significant late-
season snow and freezing rain with substantial impacts...

The first in a pair of powerful late-season winter storms will=20
continue to develop as an amplifying, negatively-tilted trough=20
lifts northeast from the central Plains this morning. This system=20
is expected to continue its northeastward track, reaching the upper
Mississippi Valley and western Great Lakes by this evening before=20
lifting into western Ontario by early tomorrow. Fueled by both Gulf
and Pacific moisture, this system is expected to produce a lengthy
stripe of significant ice, bordered by heavy snow to the north.=20

Supported by a warm nose of air aloft, snow transitioning to sleet
and freezing rain is expected from eastern South Dakota to=20
northern Michigan. Significant ice accumulations are likely for=20
portions of the region, especially over parts of northern Wisconsin
and Michigan. WPC guidance continues to show probabilities greater
than 70 percent for ice accumulations over 0.10 inch, along with a
greater than 50 percent chance for ice accumulations over 0.25=20
inch over parts of the region through early Friday.

The better chance for heavier snow will center to the north across
the Minnesota Arrowhead, where WPC probabilities show a greater=20
than 70 percent chance for snow accumulations over 4 inches.

Key Messages are in effect for this system and are linked=20
below (Key Messages #1).

...Northern New York and New England...
Days 1-3...

Moisture from the first Midwest storm will surge into New England
tonight. Cold air anchored by Canadian high pressure will initially
support snow before a transition to a wintry mix occurs.=20

Northern Maine is likely to see the longest period of snow, with=20
snow rates of 1 in/hr possible Thursday night into Friday.
WPC probabilities greater than 50 percent for snow accumulations=20
over 4 inches are largely confined to far northern Aroostook=20
County. But even areas this far north are expected to eventually
transition from snow to sleet and freezing rain.

Further to the south, from the Adirondacks to the northern New=20
England mountains, a wintry mix with accumulating ice is more=20
likely. Significant ice accumulations are most likely from the=20
White Mountains into northwestern Maine, where WPC probabilities=20
show a 50-70+ percent chance for ice accumulations over 0.10 inch=20
through midday Friday.=20

As the second system to impact the Midwest lifts northeast, a
second round of snow and ice is expected Saturday night into
Sunday, with most areas quickly transitioning from snow to sleet=20
and freezing rain.


...Pacific Northwest through Northern/Central Rockies...=20
Day 1...

A deep, cold low will continue to move inland over the Northwest=20
this morning, bringing additional snow to the Cascades as the=20
leading edge spreads into the northern Rockies.

Continued onshore flow in the wake of the system will bring=20
additional heavy snow to parts of the Cascades as snow levels=20
plunge behind a sharp cold cold front pressing south and east.

Snow is expected to wane across the Northwest by this evening, but
continue across parts of the northern and central Rockies as the
low moves across the region late today into early Friday.

The heaviest snow accumulations through early Friday are expected
to focus along the northern Rockies from western Montana to
northern Utah. WPC probabilities indicate widespread accumulations
of 6+ inches are likely, with some potential for amounts over a
foot in the higher terrain.=20

...Northern Plains to the Upper Midwest...
Days 2-3...

...Second of back-to-back systems expected to bring additional
heavy snow and icing to portions of the region late week...

As the previously described low moves east of the Rockies, a second
surface low will strengthen over the Central Plains and lift
northeast into the Upper Midwest, bringing a renewed round of=20
heavy banded snow and ice to the Northern Plains and the Upper
Midwest.

Strong lift supported in part by coupled upper jet forcing will
support snowfall rates of 1-2 in/hr across the Northern Plains.
Guidance indicates a more expansive footprint of heavy snow is
likely with this second system. WPC probabilities indicate snow
totals exceeding 8 inches are likely from southeastern North=20
Dakota and northeastern South Dakota to northern Minnesota. Within=20
this area some locations may see a foot or more, with southeastern=20
South Dakota the focus for the highest probabilities in the latest=20
WPC guidance.=20

This storm is expected to deliver another round of freezing rain=20
to portions of the region as well. Once again, parts of northern=20
Wisconsin and Michigan may be affected by the heaviest ice=20
accumulations, compounding impacts generated by the first storm.

Key Messages are in effect for this system and are linked=20
below (Key Messages #2).

Pereira


...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!_6aJ3Z3xg2CnJF4rkY-AWX4Enn3OgeTfT3DNOC5hiRfxD= lTjCCRgpwLKxlxl7_SxE0d7PpKnhboR9SgsclN9qCbk3uo$=20

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_6aJ3Z3xg2CnJF4rkY-AWX4Enn3OgeTfT3DNOC5hiRfxD= lTjCCRgpwLKxlxl7_SxE0d7PpKnhboR9SgsclN9cARK9No$=20


$$

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FOUS11 KWBC 021804
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
204 PM EDT Thu Apr 2 2026

Valid 00Z Fri Apr 03 2026 - 00Z Mon Apr 06 2026


...Upper Midwest through the Great Lakes...=20
Day 1...

...First of back-to-back significant late-season winter storms=20
wraps up late tonight into early Friday morning...

Ongoing snow, sleet, and freezing rain associated with a=20
strengthening surface low tracking across the Upper Midwest and=20
northern Great Lakes will continue this evening before ending late=20
tonight into early Friday morning. Freezing rain and icing will=20
mostly be confined to northern WI and the U.P. of Michigan,=20
transitioning to sleet and snow with northern and western extent.=20
Additional ice accumulations of more than 0.1 inches are possible=20
(30-50% chance), leading to storm total icing of as much as 0.5=20
inches, resulting in treacherous travel, and scattered power=20
outages. Colder air wrapping in on the back side of the departing=20
system may allow for some areas predominantly experiencing mixed=20 precipitation to briefly change to snow before ending, but any=20
accumulation would mainly be light with little additional impacts.

The heaviest remaining snow will primarily be focused across=20
northern Minnesota, where an additional 4+ inches is possible
(10-30% chance, locally higher in the Arrowhead) through early=20
Friday morning. Snowfall rates may approach 1" per hour at times,=20
especially this evening, before gradually lessening as the night=20
goes on. Reduced visibility and snow-covered roads will continue to
make travel difficult before conditions gradually improve late=20
tonight into early Friday morning.

Key Messages are in effect for this system and are linked=20
below (Key Messages #1).


...Northern New England...=20
Days 1 & 3...

Two rounds of mixed precipitation will bring modest accumulations
of snow, sleet, and freezing rain to Northern New England through
the weekend, but with considerable impacts across narrow corridors
due to the mixed precipitation types.

The first event will occur D1, generally 06Z/Fri - 00Z/Sat. This
first round of precipitation will be driven by robust WAA surging=20
northward from the Gulf ahead of a significant storm system moving
through the Great Lakes and Ontario, Canada. Initially, this
precipitation will begin as snow in northern VT, NH, and ME as cold
Canadian high pressure slowly retreats, but as the WAA pushes the
warm front northward, especially without any strong dry-bulb
cooling to offset the warmth, p-type transition will rapidly occur
to sleet, freezing rain, and eventually rain for the entire area.
This evolution supports the heaviest accumulations being confined
to just far northern ME where WPC probabilities for snow exceeding
4" are 30-50%. More icing than snow is expected across the rest of
Northern New England as reflected by WPC probabilities for at least
0.01" above 50% for much of the Greens, Whites, and higher
elevations of north-central ME, with locally more than 0.1"=20
possible (30-50%) across western ME and northern NH.

The first system kicks out Friday evening, and Saturday should be
dry across the area. However, a second system will track almost
identically to the first system across the Great Lakes and into
Ontario, spreading moisture into New England along the warm front
through return flow/WAA out of the Gulf. This system will again
encounter a rapidly retreating Canadian high pressure, so once
again a mix of snow, sleet, and freezing rain, is likely, with the
primary difference between the Sunday event and the Friday event
being a slightly warmer starting condition (so less snow). However,
a few inches of snow are again possible across far northern ME (WPC probabilities reach 50-70% for 2"), with locally as much as 0.1"=20
of is possible (30-50%) for the higher elevations of northern NH
and interior western ME.


...Northern/Central Rockies, Northern Plains, & Upper Midwest...=20
Days 1-3...

...Second of back-to-back systems will bring additional heavy snow
and icing to portions of the region into the weekend...

After the first low moves away Friday morning, the region will get
a very brief respite (in some places less than 18 hours) before the
next significant low pressure system impacts the area.

This next low will develop in response to a sharpening mid-level
trough which is expected to become a pronounced closed low with
height anomalies falling below the 10th percentile according to
NAEFS, which will work together with a meridionally arcing jet
streak to produce a deepening cyclone as it tracks from the lee of
the CO Rockies into the Great Lakes. This evolution will result in
widespread significant deep layer ascent through height falls and
jet dynamics, leading to widespread precipitation from the
Northern/Central Rockies, through the Northern Plains, and into the
Great Lakes, before this system departs into Canada Saturday night.

Moisture accompanying this system will also be significant, aided
by both Pacific moisture flooding eastward on modest IVT, and
increasing low-level moisture on southerly WAA emerging from the
Gulf. At the same time, mesoscale ascent will begin to intensify=20
as low to mid level fgen increases to drive omega into a TROWAL
pivoting around the cyclone as the theta-e ridge surges
north/northwest. The deep layer ascent will likely yield widespread
modest precipitation rates for snow and mixed-precipitation, but
the setup does appear to support a pivoting band of heavier
snowfall beneath the TROWAL where deformation maximizes W/NW of the
low. The depth of the upper low supports a strong band, and the WPC
prototype snowband tool indicates more than 1"/hr snowfall rates
being likely from the Dakotas through northern MN.

Where this band pivots the longest, WPC probabilities indicate a
high risk (>70%) for at least 8 inches of snow from far northern SD
through southern ND and into much of northern MN. Within this band,
more than 12 inches (isolated 18 inches) is also possible.
Southeast of this heaviest snowfall where the robust WAA pushes a
warm nose northward to cause p-type transition, WPC probabilities
indicate a high risk (>70%) for at least 0.1 inches of ice from
eastern SD through northern WI and the western U.P. of MI, with
locally significant ice of 0.25 - 0.5 inches possible (30-50%) in
far northern WI and into the U.P. This ice and snow falling atop
areas impacted from storm #1, will likely lead to prolonged
significant impacts to travel and infrastructure, including power
outages.

In addition, and primarily on D1 as the storm begins to get
organized across the Plains, mountain snow will be widespread for=20
the Northern and Central Rockies. This snow will be supported by
onshore Pacific moisture and accompanying mid-level ascent, with
local enhancement likely as a cold front pushes east leading to
upslope flow. Snow levels will fall to around 3000-4000 ft,
bringing considerable impacts to many areas passes, and WPC
probabilities for at least 6 inches are above 70% across the
Absarokas, Tetons, Big Horns and northern CO Rockies.

Key Messages are in effect for this system and are linked=20
below (Key Messages #2).

Weiss/Miller



...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!_kXLUFm19M7lezQiGLwoz158Zcumg8VVmmWeZuDZtsiuw= XYpe0DuBd0rtcNoZyWy-pLW6tm0ys6Z10b05BTXopeNJhY$=20

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_kXLUFm19M7lezQiGLwoz158Zcumg8VVmmWeZuDZtsiuw= XYpe0DuBd0rtcNoZyWy-pLW6tm0ys6Z10b05BTXteiPhjE$=20



$$

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FOUS11 KWBC 030715
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
315 AM EDT Fri Apr 3 2026

Valid 12Z Fri Apr 03 2026 - 12Z Mon Apr 06 2026


...Northern Plains and Upper Midwest...=20
Days 1-2...

...Second of back-to-back systems will bring additional heavy snow
and icing to portions of the region into the weekend...

The second significant late-season winter storm in 48 hours is
currently organizing as a deep closed low tracks across the
northern Rockies this morning. This system, characterized by
anomalously low heights and deep moisture from both the Gulf and
the Pacific, is expected to track east of the northern Rockies to
the upper Great Lakes over the next 36 hours. As the system moves
into the northern Plains, guidance continues to show a band of=20
heavy snow (1+ in/hr rates) developing within the associated
deformation axis later today. As this band pivots over the=20
Dakotas, heavy accumulations are likely. Bands of heavier snow are
expected to begin shifting into northern Minnesota by this evening
and then continue into Saturday before winding down late in the=20
day as the low begins to track east of the Great Lakes. The latest=20
WPC guidance indicates accumulations greater than 8 inches are=20
likely to cover much of the northern third of South Dakota, the=20
southern half of North Dakota, and northern Minnesota from the=20
North Dakota border to the Arrowhead, with embedded totals over a=20
foot expected within this area.

Significant freezing rain is expected on the warmer, eastern flank
of the system. Measurable ice is forecast from eastern South=20
Dakota and northwestern Iowa to northern Michigan, with the most=20
significant accumulations expected across northern Wisconsin and=20
the western U.P. WPC probabilities indicate ice accumulations of=20
0.10-0.25 inch, with locally heavier amounts, are likely across=20
this area.=20

Sandwiched between the axes of heaviest snow and freezing rain will
likely be a stripe of appreciable sleet, with accumulations around
0.5 inch in spots.

Key Messages are in effect for this system and are linked below=20
(Key Messages #2).


...Northern New England...=20
Days 1-3...

Two distinct rounds of mixed precipitation, driven by warm air
advection interacting with retreating cold air, will impact the
region today and then over the weekend.

Precipitation will continue to spread north through the morning
across New England, with most areas in northern New England=20
transitioning quickly to sleet and freezing rain after a brief
period of snow. An eventual change to all rain is expected for most
areas by this evening as low pressure over eastern Canada=20
continues to track toward the region.

Precipitation is expected to wane Friday night, with dry=20
conditions likely through Saturday until the system detailed above=20
follows a similar track east of the Great Lakes. Once again, any=20
snow will be short-lived with precipitation quickly changing over=20
to sleet and freezing rain, and then eventually rain as any=20
lingering cold air gives way to warm air rushing north of what is=20
forecast to become an amplified low.

For both rounds, snow accumulations greater than an inch will
likely be mostly confined to far northern Maine, while ice
accumulations, mostly on the order of 0.1 inch or less are expected
from northern New Hampshire through northern Maine.

Pereira

...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_BPWNrw80LbZBtcJYID52HDa1XMmF93rnKTY3YAA4c30j= IPOrR6OSXS1asUK7RutBn9B2v5RoXDWtrjwZO1OY4Px9qU$=20


$$

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FOUS11 KWBC 031806
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
206 PM EDT Fri Apr 3 2026

Valid 00Z Sat Apr 04 2026 - 00Z Tue Apr 07 2026


...Northern Plains and Upper Midwest...=20
Day 1...

...Second of back-to-back systems will bring additional heavy snow
and icing to portions of the region through Saturday...

Significant late-season winter storm is ongoing this morning across
the Dakotas, and will expand steadily this evening and continue
through Saturday before winding down from SW to NE Saturday night.
This significant low will track northeast from the Central Plains
through the Great Lakes while exhibiting at least modest deepening
thanks to impressive 500mb height falls downstream of a closed low
with height anomalies around the 10th percentile according to NAEFS
ensemble tables.=20

As this upper low and the accompanying surface cyclone track E/NE
through Saturday, downstream moisture advection will intensify
leading to impressive isentropic ascent, especially along the
290-295K surfaces, lifting into the Upper Midwest. Mixing ratios
within these layers of 3-5 g/kg reflect the anomalous moisture=20
being wrapped into the system, and it is likely that precipitation=20
will become increasingly widespread through this evening and into=20
Saturday. At the same time, the accompanying theta-e ridge will=20
wrap cyclonically around the system and lift into a TROWAL, while=20
the impressive upper low forces intense deformation to drive=20
tremendous ascent into the TROWAL. The combination of the deep=20
layer ascent with robust mesoscale forcing will result in banded=20
structures with snowfall rates for which the WPC prototype snowband
tool suggests will reach 1-2"/hr at times, especially from eastern
ND into northern MN where some pivoting of these bands may also=20
occur. This will result in heavy snowfall accumulations, and WPC=20 probabilities indicate a 50-90% chance of at least 8 inches of=20
snow, with locally 12-18" possible (30% chance).

Farther southeast, the strong WAA east of the upper low will cause
a warm nose to push rapidly northward leading to an area of heavy
mixed precipitation including sleet and freezing rain. The regional
forecast soundings from eastern MN through northern WI and into the
western U.P. of MI indicate a deep cold layer beneath this warm
nose, so p-type will likely start as sleet in many areas. However,
warm nose energy rapidly increases leading to a changeover to an
extended period of freezing rain before the dry slot pushes
northward (likely preventing a changeover to rain in some areas).
While sleet accumulations on both shores of Lake Superior may reach
0.5", the more significant hazard is expected to be freezing rain
where WPC probabilities are high (>70%) for at least 0.1" of ice,
and locally there is a moderate risk (30-50%) for 0.25-0.5" of ice
for far northern WI into the western U.P. of MI. This icing could
be damaging, causing power outages and tree damage, and will likely
exacerbate and prolong impacts ongoing from the ice/snow which
occurred with the earlier system on Thursday.

Key Messages are in effect for this system and are linked below=20
(Key Messages #2).


...Northern New England...=20
Day 2...

A warm front extending eastward from a significant low pressure
across the Great Lakes will result in expanding precipitation
Saturday night into Sunday. Although the low itself will track well
northwest of the region, impressive warm/moist advection surging
northward from the Gulf will spread PW anomalies to as much as +3
sigma on an 850mb LLJ reaching as high as 50 kts. As this occurs, a
Canadian high pressure initially placed just north of the region
will rapidly retreat to the northeast, allowing the warm air to
flood unimpeded northward, lifting a warm nose above 0C all the way
into Canada. This suggests that precipitation will begin as a
period of snow across northern Maine, but will otherwise be a
combination of sleet/freezing rain, especially in the higher
elevations, before transitioning to all rain by Sunday aftn.=20

Total accumulations of any individual wintry precipitation type
will likely be modest as the warm air overwhelms the column, but
impactful snow and ice is still likely. This is reflected by WPC
probabilities for 4+ inches of snow that reach 10-30% in far
northern ME (just Aroostook County), and WPC probabilities for ice
exceeding 0.1" reaching 10-30% in the higher terrain of northern NH
and interior/western ME.


Weiss


...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_RTUz_614JoHj-DnsYqKZMHb3ujwYTJa4xgb7BGgRWKI3= LpnUbvsVPDM6Qb8x-CpR28EkFUbkpt4uaL1tqIuH_W-mR0$=20



$$

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FOUS11 KWBC 040726
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
326 AM EDT Sat Apr 4 2026

Valid 12Z Sat Apr 04 2026 - 12Z Tue Apr 07 2026


...Northern Plains, Upper Midwest, & Western Great Lakes...
Day 1...

...Second of back-to-back systems will bring additional heavy snow
and icing to portions of the region today...

Significant late-season winter storm is ongoing this morning extending
from the Dakotas across the Midwest towards the MI U.P.. Moderate
to heavy snow occurring across the Dakotas is expected to diminish
by midday as snowfall continues across central and northern MN=20
through this evening. Meanwhile, to the north and northeast of the=20 associated low pressure system, freezing rain will be the primary=20
winter precipitation type throughout northern WI and both the U.P.=20
and northern L.P. of MI. This significant low will track northeast=20
from the Midwest through the Great Lakes by this evening and=20
quickly exit into southeast Canada tonight while hazardous winter=20 precipitation concludes as well.=20

As this low pressure system and accompanying upper low track E/NE=20
today, continuing downstream moisture advection will peak later
this morning leading to impressive isentropic ascent, especially=20
along the 290-295K surfaces, lifting into the Upper Midwest. Mixing
ratios within these layers of 3-5 g/kg reflect the anomalous=20
moisture being wrapped into the system, and it is likely that=20
precipitation will become even more widespread by sunrise this
morning. At the same time, the accompanying theta-e ridge will=20
wrap cyclonically around the system and lift into a TROWAL, while=20
the impressive upper low forces intense deformation to drive=20
tremendous ascent into the TROWAL. The combination of the deep=20
layer ascent with robust mesoscale forcing will result in banded=20
structures with snowfall rates for which the 00z HREF suggests=20
will reach 1-2"/hr at times, especially from eastern ND into=20
northern MN where some pivoting of these bands may also occur. This
will result in heavy total snowfall accumulations around one foot.
However, just outside of these pivoting heavier bands and within
lighter snow rates, totals will likely be limited by the early=20
April sun- angle combined with surface temperatures in the low-30s.
WPC probabilities start at 12Z today (heavy snow is ongoing before
12Z as well) and indicate a 50-80% chance of at least 8 inches of=20
additional snow in northern/northeastern MN today.

Farther southeast, the strong WAA east of the upper low and a warm
nose pushing northward is leading to an area of heavy mixed=20
precipitation including sleet and freezing rain. Even with a deep
cold layer and period of sleet, warm nose energy rapidly increases
this morning leading to a changeover to an extended period of=20
freezing rain before the dry slot pushes northward (likely=20
preventing a changeover to rain in some areas) this afternoon.=20
While sleet accumulations on both shores of Lake Superior may reach
0.5", the more significant hazard is expected to be freezing rain=20
where the latest WSSI depicts widespread Moderate Impacts
associated with freezing rain from northern WI to the eastern=20
U.P.. This icing could be damaging where totals exceed a quarter=20
inch, causing power outages and tree damage, and will likely=20
exacerbate and prolong impacts ongoing from the ice/snow which=20
occurred with the earlier system on Thursday.

Key Messages are in effect for this system and are linked below=20
(Key Messages #2).


...Northern New England...=20
Days 1-2...

A warm front extending eastward from a significant low pressure
across the Great Lakes will result in expanding precipitation
tonight into Sunday. Although the low itself will track well=20
northwest of the region, impressive warm/moist advection surging=20
northward from the Gulf will spread PW anomalies to as much as +3=20
sigma on an 850mb LLJ reaching as high as 50 kts. As this occurs, a
Canadian high pressure initially placed just north of the region=20
will rapidly retreat to the northeast, allowing the warm air to=20
flood unimpeded northward, lifting a warm nose above 0C all the way
into Canada. This suggests that precipitation will begin as a=20
period of snow across northern Maine, but will otherwise be a=20
combination of sleet/freezing rain, especially in the higher=20
elevations, before transitioning to all rain by Sunday aftn.=20

Total accumulations of any individual wintry precipitation type
will likely be modest as the warm air overwhelms the column, but
impactful ice is most likely. This is reflected by WPC=20
probabilities for ice exceeding 0.1" reaching 30-60% in the higher
terrain of northern NH and interior/western ME.


Snell/Weiss



...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!7-wqkXAXEAhei98H4zGUIqbrdkbPBibX_Ay6RBKrVIlnI= 6QA8n9Z7a38ZGGBam9_UiMOV-uhVff4GqNeA51OBIyDIEY$=20



$$

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FOUS11 KWBC 041803
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
203 PM EDT Sat Apr 4 2026

Valid 00Z Sun Apr 05 2026 - 00Z Wed Apr 08 2026


...Northern Plains, Upper Midwest, & Western Great Lakes...
Day 1...

...Significant winter storm ongoing today will wind down this=20
evening...

The significant winter storm which has produced over a foot of snow
in parts of the Dakotas and more than 1/4 inch of ice in Wisconsin
will continue today, but wane quickly after 00Z, with all wintry=20 precipitation coming to an end by 12Z Sunday. Snowfall lingering=20
across northern MN after 00Z will generally be underneath the=20
remnant pivoting deformation band as it crosses more firmly into=20
Canada, with some light snow developing on lake enhancement into=20
the western U.P. of MI overnight as well. Snowfall rates within any
of these snow areas are expected to be modest as the most=20
significant forcing pulls away to the east, leading to just=20
additional light snowfall accumulations of just 2-4", highest in=20
the western U.P. Despite this modest additional accumulation,=20
impacts from this storm will linger through the weekend after this=20
heavy snow and significant icing, which only compounded impacts=20
from Thursday's system.

Key Messages are in effect for this system and are linked below=20
(Key Messages #2).


...Northern New England...=20
Day 1...

Precipitation will spread across northern New England tonight and
continue through Sunday afternoon as a warm front extending from a
significant system in the Great Lakes moves into the region.
Moisture will spread northward from the Gulf and ascent
isentropically atop the warm front, expanding the precipitation
shield but also driving a warm nose >0C northward as Canadian high
pressure retreats. The timing of the heaviest wintry precipitation
is likely between 06Z/Sunday to 18Z/Sunday, during which time a
mixture of snow, sleet, and freezing rain will occur before
transitioning to all rain. Total accumulations of any wintry
precipitation are expected to be modest, but still produce impacts
to travel as reflected by 20-40% chance for moderate impacts in the
WSSI-P, focused over the higher terrain of NH and ME. WPC
probabilities for snow exceeding 4" are just around 10% across
northern Aroostook County, ME. Freezing rain is likely to be more
widespread as at least a glaze of ice is possible for the higher
terrain of the Adirondacks and all of central/northern New England.
However, significant icing exceeding 0.1" is expected to be
confined to just the higher terrain of NH and ME where WPC
probabilities are 30-50%.


...Great Lakes...
Day 2...

A fast moving and compact shortwave diving out of Manitoba will
race southeast and cross the western Great Lakes Monday before
becoming embedded in the broad cyclonic flow across the Northeast.
This shortwave will help develop a weak wave of low pressure along
an inverted surface trough tracking southeast across Michigan
Monday. Any warm advection snowfall may stay just north of the
region, but sufficient cold advection behind this wave will drop
850mb temps down to below -15C, sufficient for late season lake
effect snow (LES) as lapse rates steepen atop the slowly warming
Great Lakes. Heavy snow is likely to develop within this CAA south
of Lake Superior, especially along the western U.P. of MI where WPC probabilities for 4+ inches are 50-70%.


Weiss


...Winter Storm Key Messages are in effect. Please see current=20
Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_2.png__;!!DZ3fjg!_5iLgzzq9ZNwfJR9f8Tf9B1M8oC-MmIbhqhf9hy6VB333= RCV4NLi3YBaTrVOvyR8ffPg2dN_TGg35yrK7tVfADs4Kcg$=20



$$

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FOUS11 KWBC 050659
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
259 AM EDT Sun Apr 5 2026

Valid 12Z Sun Apr 05 2026 - 12Z Wed Apr 08 2026


...Northern New England...
Day 1...

Scattered precipitation across northern New England early this
morning will become more widespread through this afternoon as a
warm front lifts northward towards the region ahead of a system
approaching from the Great Lakes. Moisture will continue spreading
northward from the Gulf and ascent isentropically atop the warm
front, expanding the precipitation shield but also driving a warm
nose >0C northward as Canadian high pressure retreats. The timing
of the heaviest wintry precipitation is likely prior to
18Z/Sunday, during which time a mixture of snow, sleet, and
freezing rain will occur before transitioning to all rain. Total
accumulations of any wintry precipitation are expected to be
modest, but still produce impacts to travel as reflected by 20-40%
chance for moderate impacts in the WSSI-P, focused over the higher
terrain of NH and ME. Freezing rain is likely to produce the most
impacts as at least a glaze of ice is possible for the higher
terrain of northern New England. However, significant icing
exceeding 0.1" is expected to be confined to just the higher
terrain of NH and ME.

Following the cold frontal passage this evening, strengthening CAA
along with modest height falls and steepening lapse rates will
allow for upslope snow showers and snow squalls from the
Adirondacks through northern VT/NH/ME into Monday.


...Great Lakes...
Days 1-3...

A fast moving and compact shortwave diving out of Manitoba will
race southeast and cross the western Great Lakes Monday before
becoming embedded in the broad cyclonic flow across the Northeast
on Tuesday. This shortwave will help develop a weak wave of low
pressure along an inverted surface trough tracking southeast across
Michigan Monday. Any warm advection snowfall may stay just north
of the region, but sufficient cold advection behind this wave will
drop 850mb temps down to below -15C, sufficient for late season
lake effect snow (LES) and diurnal snow shower activity as lapse
rates steepen atop the slowly warming Great Lakes. Heavy snow is
likely to develop within this CAA south of Lake Superior,
especially along the western U.P. of MI, and downwind of Lake Erie
along the shores of western New York. Here, WPC probabilities for
4+ inches are 40-60% in the MI U.P. for Days 1-2 and 50-80% in far
western NY Days 2-3.


Snell/Weiss



$$

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FOUS11 KWBC 051814
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
214 PM EDT Sun Apr 5 2026

Valid 00Z Mon Apr 06 2026 - 00Z Thu Apr 09 2026


...Great Lakes & Northeast...
Days 1-2...

Compact shortwave digging out of Manitoba will race southeast,
crossing the Upper Midwest and Great Lakes Monday before becoming
embedded into the more synoptic cyclonic flow across the Northeast
by Tuesday. This will help spawn a weak wave of low pressure along
an inverted surface trough, with locally enhanced moist advection
in the vicinity of this low leading to a swath of light to moderate
snowfall. The heaviest synoptic snow should be generally north of
the international border, but CAA in the wake of this impulse will
push 850mb temps down to around -15C, producing a favorable
environment for lake effect snow (LES) in the favored NW snow belts
downstream of the Great Lakes. The duration and intensity of this
LES may be somewhat modest, but significant accumulations exceeding
4" are still possible (30-70% chance) across the western U.P. on
D1, and 10-50% along the Chautauqua Ridge east of Lake Erie on D2. Additionally, although accumulations are expected to be generally
less than 2", post impulse NW flow will create some upslope
snowfall across the Adirondacks and Greens on D2.


...Missouri Valley/Corn Belt...
Day 2...

An interesting evolution Monday night into Tuesday morning could
result in a very narrow corridor of heavy snowfall from eastern
Nebraska into Iowa and Missouri. A modest shortwave dropping across
the Central Rockies will cause weak height falls and broad
divergence across the region Monday night into Tuesday. At the same
time, a potent NW to SE oriented jet streak will arc southward on
the upwind side of a trough moving over the Great Lakes/Northeast,
leaving favorable RRQ diffluence overlapping the best mid-level
divergence. This mid- level pattern will push a cold front through
the region Monday, but it is likely that this front will begin to
kink and return northward with warm advection Tuesday morning as
850mb flow returns to the S/SW creating a narrow corridor of
impressive fgen as moist isentropic upglide ascends the boundary.

The overlap of this moist isentropic ascent with the RRQ of the jet
streak aloft will create a narrow stripe of intense 850-600mb fgen,
creating a streak of heavy precipitation. With the most intense
ascent expected to lift into the deepening DGZ (50% chance of at
least 50mb of DGZ depth according to the SREF), dynamic cooling
should overcome the generally marginal thermal structure, leading
to a stripe of heavy snow with snowfall rates potentially reaching
1"/hr. There remains considerable uncertainty into the placement
of this band due to its narrow nature, as well as the intensity of
any of the snow, but WPC probabilities have increased, and now
feature a 30-50% chance of at least 2" Tuesday morning, potentially
leading to a hazardous morning commute.


Weiss


$$

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FOUS11 KWBC 060710
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
310 AM EDT Mon Apr 6 2026

Valid 12Z Mon Apr 06 2026 - 12Z Thu Apr 09 2026


...Missouri Valley/Corn Belt...
Day 1...

An interesting evolution during the second half of Day 1 (00Z -
12Z Tuesday) could result in a very narrow corridor of heavy
snowfall from eastern Nebraska into southwest Iowa and far
northern Missouri. A modest shortwave dropping across the Central
Rockies will cause weak height falls and broad divergence across
the region Monday night into Tuesday morning. At the same time, a
potent NW to SE oriented jet streak will arc southward on the
upwind side of a trough moving over the Great Lakes/Northeast,
leaving favorable RRQ diffluence overlapping the best mid-level
divergence. This mid- level pattern will push a cold front through
the region today, but it is likely that this front will begin to
kink and return northward with warm advection Tuesday morning as
850mb flow returns to the S/SW creating a narrow corridor of
impressive fgen as moist isentropic upglide ascends the boundary.

The overlap of this moist isentropic ascent with the RRQ of the jet
streak aloft will create a narrow stripe of intense 850-600mb fgen,
creating a streak of heavy precipitation. With the most intense
ascent expected to lift into the deepening DGZ (50% chance of at
least 50mb of DGZ depth according to the SREF), dynamic cooling
should overcome the generally marginal thermal structure during the
overnight hours and absent of the April sun-angle, leading to a
stripe of heavy snow with snowfall rates potentially reaching
1"/hr. There remains some uncertainty into the placement of this
band due to its very narrow nature, as well as the intensity of
any of the snow. WPC probabilities have increased, and now feature
a 30-60% chance of at least 4" by Tuesday morning from east-
central NE through southwest IA, potentially leading to a hazardous
morning commute.


...Great Lakes & Northeast...
Days 1-2...

Compact shortwave digging out of Manitoba will race southeast,
crossing the Upper Midwest and Great Lakes today before becoming
embedded into the more synoptic cyclonic flow across the Northeast
by Tuesday. This will help spawn a weak wave of low pressure along
an inverted surface trough, with locally enhanced moist advection
in the vicinity of this low leading to a swath of light to moderate
snowfall. The heaviest synoptic snow should be generally north of
the international border, but CAA in the wake of this impulse will
push 850mb temps down to around -15C, producing a favorable
environment for lake effect snow (LES) in the favored NW snow belts
downstream of the Great Lakes. The duration and intensity of this
LES may be somewhat modest, but significant accumulations exceeding
4" are still possible (30-70% chance) across the Huron Mts of the
MI U.P. on D1, and 10-20% along the Chautauqua Ridge east of Lake
Erie on D2 on north through the favored upslope regions of the
Adirondacks and Green Mts.


Snell/Weiss


$$

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FOUS11 KWBC 061750
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
150 PM EDT Mon Apr 6 2026

Valid 12Z Mon Apr 06 2026 - 12Z Thu Apr 09 2026


...Missouri Valley/Corn Belt...
Day 1...

The guidance continues to suggest that a hyper-localized by intense
band of snowfall will develop from eastern NE through southern IA
and potentially as far as northern MO tonight and persist into late
Tuesday morning. Snowfall rates within this band will likely
eclipse 1"/hr at times (80% chance from the WPC prototype snowband
tool), and as this band translates slowly E/NE. This will create
significant snow accumulations, but with a very narrow footprint,
and difficult commuting Tuesday morning.

This band is expected to develop as a weak shortwave emerges from
the Central Rockies and advects E/SE creating subtle height falls
and mid-level divergence across the area. At the same time, a
potent jet streak around 130kts will pivot eastward over the Upper
Midwest, leaving its distant RRQ over the Corn Belt. The overlap of
the best divergence and upper diffluence will occur over NE/IA,
coincident with the placement of strongest 850mb warm/moist
advection as southerly return flow emerges from the Gulf. The
concurrent surge of the accompanying theta-e ridge will drive
sufficient moisture northward, and although PWs are expected to be
near normal, there is a narrow corridor of specific humidity in the
700-500mb layer which is progged to exceed the 90th percentile
according to NAEFS. This is a perfect overlap with the strongest
fgen (within the 700-500mb layer) suggesting that a narrow band of
heavy precipitation is likely, with snow likely the primary p-type
as ascent crosses the deepening DGZ.

Surface temperatures will be around to slightly above 0C, but the
rest of the column will be sub-freezing so as soon as intensity
ramps up (which will be quickly tonight) precipitation will change
to heavy snow, with the aforementioned 1"/hr+ rates becoming
dominant within this narrow plume. As the band pivots slowly
northeast, it will lead to rapid accumulations, and the high-res
guidance is beginning to focus from eastern NE through SW IA as the
area of most intense snowfall, and many of the deterministic models
suggest 6+ inches of snow, which is aligned with the NBMv5.0 PMM.
Since most of this snow will occur overnight into the morning
hours, melting loss due to the sun is not expected to be an issue,
so while confidence in a narrow band of heavy snow with continuous
amounts over 6" remains modest, the threat for significant impacts
has increased, leading to a hazardous morning commute. WPC
probabilities have climbed dramatically with the increase in the
12Z guidance suite, and now reflect a 50-70% for at least 4 inches
from near Omaha, NE through south-central IA. Locally 6-10" of snow
is possible if this band can linger in any one area with the 1+"/hr
snowfall rates.


...Great Lakes & Northeast...
Days 1-2...

Strung out vorticity associated with a compact shortwave will swing
from the Great Lakes to the Northeast tonight and Tuesday. The
modest height falls and PVA will lead to a compact low pressure
developing along an inverted trough, and as this feature moves east
D2 it will bring periods of moderate to heavy snowfall. This event
will contain two primary mechanisms for heavy snow.

The first will be along the inverted trough immediately ahead of
the wave of low pressure. In this area, the total snowfall is
expected to be minimal, but periods of convective snow showers are
expected as low-level convergence drives ascent into an airmass
with modest instability (SBCAPE 200-300 J/kg). With pockets of
low-level fgen additionally driving ascent, some areas, especially
across Upstate NY and central/southern New England could receive
multiple rounds of snow showers with briefly heavy snow rates,
gusty winds, and periodic visibility restrictions.

The more substantial snowfall accumulations are expected behind the
wave of low pressure as CAA develops to produce low-level fgen, and
NW flow drives substantial upslope enhancement into the Adirondacks
and Greens. The coverage and intensity of this snowfall is again
expected to be modest, but where upslope flow is most pronounced,
WPC probabilities suggest a 10-30% chance of 4+ inches of snow,
especially across the Adirondacks/Greens/Whites. Developing
deformation, although modest, overlapping this CAA could cause this
swath of snowfall to progress all the way to the Atlantic coast of Massachusetts with a corridor of heavy snow rates reaching the
Portland/Boston area Tuesday night, albeit with minimal
accumulations.


Weiss


$$

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FOUS11 KWBC 070717
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
317 AM EDT Tue Apr 7 2026

Valid 12Z Tue Apr 07 2026 - 12Z Fri Apr 10 2026


...Northern Adirondacks, Green & White Mts...
Day 1...

Strung out vorticity associated with a compact shortwave will swing
from the Great Lakes to the Northeast today. The modest height
falls and PVA will lead to a compact low pressure developing along
an inverted trough, and as this feature moves east it will bring
periods of moderate to heavy snowfall through early tonight. This
event will contain two primary mechanisms for locally heavy snow.

The first will be along the inverted trough immediately ahead of
the wave of low pressure. In this area, the total snowfall is
expected to be minimal, but periods of convective snow showers are
expected as low-level convergence drives ascent into an airmass
with modest instability (SBCAPE 200-300 J/kg). With pockets of
low-level fgen additionally driving ascent, some areas, especially
across Upstate NY and central/southern New England could receive
multiple rounds of snow showers with briefly heavy snow rates,
gusty winds, and periodic visibility restrictions.

The more substantial snowfall accumulations are expected behind the
wave of low pressure as CAA develops to produce low-level fgen, and
NW flow drives substantial upslope enhancement into the Adirondacks
and Greens. The coverage and intensity of this snowfall is again
expected to be modest, but where upslope flow is most pronounced
and overlaps with the leading weak warm advection, WPC
probabilities suggest a 40-70% chance of 4+ inches of snow,
especially across the White Mts of NH and ME. Probabilities for at
least 2 inches of snow are 40-60% across a larger region
encompassing the northern Adirondacks and Green Mts of VT.
Developing deformation, although modest, overlapping this CAA could
cause this swath of snowfall to progress all the way to the
Atlantic coast of Massachusetts with a corridor of heavy snow rates
reaching the Portland/Boston area Tuesday evening, albeit with
minimal accumulations.


Snell/Weiss


$$

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FOUS11 KWBC 071810
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
210 PM EDT Tue Apr 7 2026

Valid 00Z Wed Apr 08 2026 - 00Z Sat Apr 11 2026


The probability of significant snow and ice across the CONUS is
less than 10 percent.


Miller


$$

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FOUS11 KWBC 080632
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
232 AM EDT Wed Apr 8 2026

Valid 12Z Wed Apr 08 2026 - 12Z Sat Apr 11 2026


...Sierra Nevada...
Day 3...

Precipitation returns to the West Coast late this week and early
this upcoming weekend as a closed upper low slowly approaches the
California coastline on Friday and interacts with a separate system
dropping southeast from the Gulf of Alaska late Friday night. Snow
levels are forecast to remain rather high through Saturday morning
above 8000ft and higher than many major passes. Current WPC
probabilities valid through the end of Day 3 are low (20-40%) for
at least 6 inches of snowfall across the Sierra Nevada and mostly
for remote locations with an elevation above 9500ft. However, snow
levels are expected to lower by the very end of the short range
forecast period (12Z Saturday) potentially down to around 7500ft
and should continue to lower somewhat throughout the weekend into
next week.


Snell


$$

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FOUS11 KWBC 081855
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
255 PM EDT Wed Apr 8 2026

Valid 00Z Thu Apr 09 2026 - 00Z Sun Apr 12 2026


...Sierra Nevada...
Day 3...

A closed upper level low off the coast of California will
break down into open wave as it comes ashore Friday night into
Saturday. Quick on its heels will be a stronger and more compact
closed low which is set to make landfall over northern California
Saturday night into Sunday. In tandem, these features will send
waves of impressive moisture inland, headlined by PW anomalies of
150 to 200 percent of normal. These surges of moisture will
interact with the higher terrain of the Sierra Nevada, leading to
periods of moderate to heavy snow beginning Day 3 (Friday night
into Saturday) and continuing into the weekend. Southwest flow
ahead of these systems will initially keep snow levels relatively
high (generally above 9000ft). However, as colder air works in from
the west and northwest, snow levels are expected to drop closer to
6000ft by Saturday evening, and perhaps as low as 4500ft by early
Sunday morning.

The latest WPC probabilities for >6" of snow have increased with
this forecast package, and are now up to 50-80% across a large
portion of the Sierra Nevada. Meanwhile, probabilities for >12" of
snow have also increased, now up to 20-50% across the higher peaks
of the Sierra. Travel across the higher mountain passes will
increasingly become a concern through the weekend as snow levels
lower, which is highlighted by 40-80% WSSI-P probabilities for
moderate impacts.


Miller


$$

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FOUS11 KWBC 090716
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
316 AM EDT Thu Apr 9 2026

Valid 12Z Thu Apr 09 2026 - 12Z Sun Apr 12 2026


...Sierra Nevada...
Days 2-3...

A robust closed low will drop SSEward from the Gulf of Alaska
tomorrow and move into NorCal Saturday night into Sunday. Ahead of
that system a lead upper low will weaken into an open wave tonight
over NorCal but will bring in some moisture to the region. But it
will be the second system that will be the primary driver for
snowfall over the Sierra from late Friday/early Saturday through
Sunday (beyond this forecast period). Though moisture/IVT anomalies
will be modestly high (90th-95th percentile), the slow-moving
upper low will allow for a longer sustained fetch into the Sierra.
Moderate to heavy snow is expected over the High Sierra at first,
then lowering through many passes as colder air filters in. Snow
levels at precip onset tonight will be above 9000ft but fall to
7500-8000ft Friday morning, 6000ft Saturday morning, and
4000-4500ft Sunday morning. The heaviest snow is expected Saturday
afternoon through the overnight hours with rates of 1-3"/hr.

WPC probabilities for >6" of snow are >50% above 5000ft or so and
for >12" are >50% above 6000-7000ft or so. Total snowfall could
exceed 2-3ft for the event in the higher peaks (>50% chance).
Travel across the higher mountain passes (including I-80) will
increasingly become a concern through the weekend as snow levels
lower. Minor to moderate impacts can be expected over the Sierra
per the WSSI, with isolated major impacts in the High Sierra.

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso


$$

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FOUS11 KWBC 091815
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
215 PM EDT Thu Apr 9 2026

Valid 00Z Fri Apr 10 2026 - 00Z Mon Apr 13 2026


...Sierra Nevada...
Days 2-3...

A lead upper low will weaken into an open wave tonight as it moves
inland over NorCal. Quick on its heels, a more robust closed low
will drop from the Gulf of Alaska on Friday and move into NorCal
Saturday night into Sunday. The lead wave will have some initial
moisture with it, but it will be the second, stronger system that
will be the primary driver for snowfall over the Sierra from late
Friday/early Saturday through Sunday. While moisture/IVT anomalies
will only be modestly high (90th-95th percentile), the slow-moving
nature of the upper low will allow for a longer sustained fetch
into the Sierra. Moderate to heavy snow is expected over the High
Sierra at first, then lowering through many passes as colder air
filters in. Snow levels at precip onset tonight will be above
9000ft but fall to 7500-8000ft Friday morning, 6000ft Saturday
morning, and 4000-4500ft Sunday morning. The heaviest snow is
expected Saturday afternoon through early Sunday morning with
rates of 1-3"/hr.

WPC probabilities for >8 of snow are >50% above 5000ft or so and
for >12" are >50% above 6000-7000ft or so. Total snowfall could
exceed 2-3ft for the event in the higher peaks (>50% chance).
Travel across the higher mountain passes (including I-80) will
increasingly become a concern through the weekend as snow levels
lower. Minor to moderate impacts can be expected over the Sierra
per the WSSI, with isolated major impacts in the High Sierra.

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso/Miller





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FOUS11 KWBC 100646
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
246 AM EDT Fri Apr 10 2026

Valid 12Z Fri Apr 10 2026 - 12Z Mon Apr 13 2026

...Sierra Nevada...
Days 1-3...

An upper low just offshore NorCal this morning will will weaken
into an open wave this afternoon as it moves inland into the Great
Basin. Moisture is already flowing into the region but temperatures
are mild and snow levels are quite high (>9000ft). Just upstream,
a more robust closed low will drop southward from the Gulf of
Alaska and move into NorCal Saturday night through Sunday and
slowly weaken into Monday. This second stronger system will be the
primary driver for snowfall over the Sierra starting tonight and
continuing through the weekend. While moisture/IVT anomalies will
be modestly high (90th-98th percentile), the slow-moving nature of
the upper low will allow for a longer sustained fetch into the
Sierra at a fairly favorable wind direction from the SW. Moderate
to heavy snow is expected over the High Sierra at first, then
lowering through many passes as colder air filters in. Snow levels
above 9000ft will fall to 7500-8000ft today, 6000ft Saturday
morning, and 4000-4500ft Sunday morning before rising a bit later
in the day into early Monday (5000-5500ft) as the upper low starts
to weaken. The heaviest snow is expected late Saturday afternoon in
northern areas through Sunday across the rest of the Sierra with
rates of 1-3"/hr per the hires CAMS and WPC snowband probability
tracker page.

WPC probabilities for >8" of snow are >50% above 5000-5500ft or so
and for >18" are >50% above 6000-7000ft or so. Total snowfall for
the event could reach 2ft in the higher peaks above 8000ft (>50%
chance) and 4ft in the High Sierra peaks. Travel across the higher
mountain passes (including I-80) will increasingly become a concern
through the weekend as snow levels lower. Moderate to Major level
impacts can be expected over the Sierra per the WSSI.

Snow will also expand across the Great Basin on Sunday with minor
accumulations for most areas. However, parts of southeastern OR,
northern NV, the central ID ranges, and the Wind River Range in WY
could see in excess of 8 inches of snow through 12Z Mon (40-70%
chance).

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso


$$

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FOUS11 KWBC 101859
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
259 PM EDT Fri Apr 10 2026

Valid 00Z Sat Apr 11 2026 - 00Z Tue Apr 14 2026

...Sierra Nevada & Northern California...
Days 1-3...

An upper low opening up off the northern CA coast will weaken, but
be quickly replaced by an even more potent upper low diving south
from Alaska to take up residence in a similar position by 00Z
Sunday. This deeper low is then forecast to drop slowly E/SE to
come onshore the Bay Area by 00Z Monday, before opening into a
longwave positively tilted trough centered over the Great Basin by
the end of the forecast period.

Forcing for ascent will maximize downstream of this secondary upper
low as mid-level divergence and height falls overlap into central
and northern CA. This will be accompanied by the LFQ of a
sharpening subtropical jet streak rotating around the upper low,
and the overlap of these features is expected to drive considerable
synoptic lift across the region, with orographic enhancement likely
into the Sierra and northern CA terrain due to the onshore 700mb
flow. This lift will act upon a rapidly moistening column as IVT
surges onshore (90% chance for at least 250 kg/m/s) leading to PW
anomalies reaching +1 to +2 sigma across much of CA.

This will result in an area of expanding precipitation, especially
00Z/Sun to 12Z/Mon over CA, with some modest spillover and spread
of precipitation into the Rockies and Great Basin thereafter.
However, the heaviest precip is expected in the Sierra and northern
CA terrain, which are also the areas that will experience heavy
snowfall as they will be above the falling snow levels. As far as
snow levels, they are expected to begin around 6000-8000 ft, but
will fall quickly through Sunday and into Monday as the upper low
moves onshore, becoming as low as 4500 ft, but steep lapse rates
beneath the upper low may cause snow to accumulate below 4000 ft as
reflected by the NBM 10th percentile.

Heavy snow rates reaching 1-3"/hr as progged by the WPC prototype
snowband tool in the terrain combined with 24-36 hours of moderate
to heavy snow will result in significant accumulations that have a
high risk (>70% chance) of reaching at least 18", with locally 2-3
feet possible (30-70% chance), highest in the high Sierra. This
will create moderate to major (70% chance of major) impacts across
the Sierra including many of the important passes.

Lesser, but still significant snow may expand across the Great
Basin and into parts of the Northern Rockies, leading to pockets of
WPC probabilities exceeding 30% for 8+ inches in the highest
elevations of NV, southern OR, and parts of ID.

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Weiss


$$

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FOUS11 KWBC 101900
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Fri Apr 10 2026

Valid 00Z Sat Apr 11 2026 - 00Z Tue Apr 14 2026

...Sierra Nevada through the Northern Rockies...
Days 1-3...

An upper low opening up off the northern CA coast will weaken, but
be quickly replaced by an even more potent upper low diving south
from Alaska to take up residence in a similar position by 00Z
Sunday. This deeper low is then forecast to drop slowly E/SE to
come onshore the Bay Area by 00Z Monday, before opening into a
longwave positively tilted trough centered over the Great Basin by
the end of the forecast period.

Forcing for ascent will maximize downstream of this secondary upper
low as mid-level divergence and height falls overlap into central
and northern CA. This will be accompanied by the LFQ of a
sharpening subtropical jet streak rotating around the upper low,
and the overlap of these features is expected to drive considerable
synoptic lift across the region, with orographic enhancement likely
into the Sierra and northern CA terrain due to the onshore 700mb
flow. This lift will act upon a rapidly moistening column as IVT
surges onshore (90% chance for at least 250 kg/m/s) leading to PW
anomalies reaching +1 to +2 sigma across much of CA.

This will result in an area of expanding precipitation, especially
00Z/Sun to 12Z/Mon over CA, with some modest spillover and spread
of precipitation into the Rockies and Great Basin thereafter.
However, the heaviest precip is expected in the Sierra and northern
CA terrain, which are also the areas that will experience heavy
snowfall as they will be above the falling snow levels. As far as
snow levels, they are expected to begin around 6000-8000 ft, but
will fall quickly through Sunday and into Monday as the upper low
moves onshore, becoming as low as 4500 ft, but steep lapse rates
beneath the upper low may cause snow to accumulate below 4000 ft as
reflected by the NBM 10th percentile.

Heavy snow rates reaching 1-3"/hr as progged by the WPC prototype
snowband tool in the terrain combined with 24-36 hours of moderate
to heavy snow will result in significant accumulations that have a
high risk (>70% chance) of reaching at least 18", with locally 2-3
feet possible (30-70% chance), highest in the high Sierra. This
will create moderate to major (70% chance of major) impacts across
the Sierra including many of the important passes.

Lesser, but still significant snow may expand across the Great
Basin and into parts of the Northern Rockies, leading to pockets of
WPC probabilities exceeding 30% for 8+ inches in the highest
elevations of NV, southern OR, and parts of ID.

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Weiss





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FOUS11 KWBC 110623
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
223 AM EDT Sat Apr 11 2026

Valid 12Z Sat Apr 11 2026 - 12Z Tue Apr 14 2026

...Sierra Nevada and Rockies...
Days 1-3...

Light snow associated with a weakening upper trough moving east of
the northern Sierra will continue into the afternoon in advance of
a more potent upper low diving south from Alaska. This deeper low
will move into NorCal tonight before slowly opening into a longwave positively-tilted trough Monday around Reno and continuing into
Utah by early Tuesday morning.

Despite the overall weakening of the upper low through the period,
the combination of modest moisture anomalies (>90th-95th
percentiles for PW/IVT), incoming height falls, mid- level
divergence, an incoming 120kt jet streak, and upslope enhancement
via favorable mid-level flow will yield moderate to locally heavy
snow for tonight into Sunday over the Sierra.

The heaviest snowfall over the Sierra will be just in advance of
the upper/sfc low tonight through Sunday. Snow will also expand
eastward and northeastward across the Great Basin via broad SW flow
and PVA in the mid-levels. Snow levels will continue to fall today
into Sunday from around 6000-7000ft to around/below 4500ft with
the core of the colder air aloft. Snow rates of 1-3"/hr are likely
in the Sierra, making for difficult travel across the passes (WSSI
Moderate to Major impacts).

WPC probabilities of at least 8 inches of snow are >50% above
about 4500-5000ft in the Sierra and for at least 18 inches of snow
are >50% above about 5500-6000ft. Total accumulations may exceed
2-4ft in the highest peaks with windy conditions as well.

For the Great Basin to the Rockies, light to locally modest snow
in association with the incoming system will spread across the
region Sunday and continue through Monday. WPC probabilities for at
least 8 inches of snow are >50% above about 8000ft over eastern
NV/OR into the central Idaho ranges and above 10,000-11,000ft into
the Wind River Range and the Uintas.

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso

$$

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FOUS11 KWBC 111752
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
152 PM EDT Sat Apr 11 2026

Valid 12Z Sat Apr 11 2026 - 12Z Tue Apr 14 2026

...Sierra Nevada and Rockies...
Days 1-3...

Anomalously deep low (500-700mb heights below the 0.5 percentile of
the CFSR climatology according to NAEFS) will spin onshore
California north of San Francisco by Sunday morning, and then
gradually weaken into an open trough as it progresses into the
Great Basin on Monday. Despite this steady weakening of the upper
feature, impressive ascent through height falls, PVA, divergence,
and upper jet streak, and strong orographic lift will create
widespread precipitation falling as snow in the higher elevations.
The heaviest snow is likely D1 across the Sierra when the WPC
prototype snowband tool indicates a high chance for 1-3"/hr
snowfall rates as snow levels fall to around 4500 ft beneath the
core of the upper low. This will create dangerous travel across
many of the Sierra Passes, with some of the northern California
passes (through the Shasta/Trinity region) also experiencing
hazardous travel due to heavy snow. WPC probabilities D1 are high

90%) for at least 12 inches of snow in the Sierra, with locally

2-3 feet possible before snow wanes quickly during D2. In the
Shasta/Trinity region, WPC probabilities D1 are moderate to high
for 12 inches.

Farther east into the Great Basin and the Rockies, light to
locally modest snow in association with the incoming system will
spread across the region Sunday and continue through Monday. WPC
probabilities for at least 6 inches of snow are >50% above about
8000ft over eastern NV/OR into the central Idaho ranges and above 10,000-11,000ft into the Wasatch and the Uintas.


...Washington...
Day 3...

Pinched mid-level flow south of a closed low dropping south along
the coast of British Columbia will combine with a zonally oriented
Pacific jet streak to drive moisture into Washington D3. This is
reflected by an IVT surge exceeding 300 kg/m/s according to the
West-WRF, with the core of this plume moving onshore Tuesday aftn
before steadily dropping southeast through 00Z/Wednesday. This
will manifest as increasing moisture and precipitation in a
relatively narrow corridor late D3 and continuing beyond this
forecast period. The overall column will be marginal for any wintry precipitation initially, but as the upper low approaches and a cold
front drops southward, snow levels will fall from 4000-5000 ft to
as low as 3000 ft by 00Z/Wednesday. This suggests most of the
significant accumulations will occur above many of the passes,
where WPC probabilities are 50-70% for at least 6 inches of snow,
but some light/slushy accumulations are possible as low as Stevens
and Snoqualmie Passes very late D3 and into D4 before snowfall
wanes on Wednesday.


...Colorado Rockies...
Day 3...

Closed mid-level low over the Great Basin Monday will open into a
positively tilted trough as it swings eastward, with an embedded
shortwave and vorticity maxima rotating through its base on
Tuesday. While there are considerable amplitude differences
through this evolution, the timing is generally well aligned among
the various ensemble camps, suggesting this shortwave/vorticity
maxima will move into the Central Rockies around 12Z Tuesday. The
corresponding ascent (through height falls and divergence) will
work in tandem with the LFQ of a poleward arcing jet streak to
drive lee cyclogenesis in eastern CO, with this low shifting
rapidly northeast into the Central Plains by the end of the
forecast period.

The mid-level SW flow will transport moisture into the area, while
increasing low-level southerly flow will tap some Gulf moisture as
well. However, the speed of this system ejecting northeast should
limit the ability of the accompanying theta-e to surge into CO, and
this is reflected by PWs that are progged to be around normal
according to NAEFS ensemble tables. Still, sufficient moisture
being wrung out by the impressive synoptic ascent will produce
areas of precipitation across the CO Rockies, with snow falling
above wavering snow levels between 6500-8000 ft. Total snowfall
will be somewhat modest, but WPC probabilities D3 indicate a 50-70%
chance of at least 4 inches across the San Juans and other higher
peaks of western CO.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Weiss


$$

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FOUS11 KWBC 120643
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
243 AM EDT Sun Apr 12 2026

Valid 12Z Sun Apr 12 2026 - 12Z Wed Apr 15 2026

...Sierra Nevada to the Rockies...
Days 1-3...

Deep upper low will move into NorCal today and continue to weaken
with its lead surface cold front already moving into/through the
Sierra. Despite this steady weakening of the upper feature,
impressive ascent through height falls, PVA, divergence, an upper
jet streak, and strong orographic lift will create widespread
precipitation falling as snow in the higher elevations. Though some
heavy snow has already fallen, additional modest to perhaps
heavier snow will continue in waves today over the Sierra with
1-2"/hr snowfall rates. Snow levels will fall to around 4500 ft
beneath the core of the upper low and create dangerous travel
across many of the Sierra Passes. WPC probabilities for at least an
additional 12 inches of snow are >50% above about 5000ft or so.

Farther east into the Great Basin and the Rockies, light to
locally modest snow in association with the incoming system will
spread across the region today and continue through Monday as broad
SW flow continues. By Tuesday, trailing vorticity on the SW side
of the weakening upper low this morning will move into the Four
Corners, enhancing snowfall over especially southwestern CO, but
more broadly over over the rest of the CO Rockies and also across
the Wasatch and Uintas. Snow levels initially around 8000-9000ft
will fall to around 7500ft by later Tuesday as most of the snow
ends from west to east. WPC probabilities for at least 6 inches of
snow are >50% above about 8000ft over eastern NV/OR into the
central Idaho ranges due to the lead upper trough today into
Monday, and above 10,000-11,000ft into the Wasatch, Uintas, and San
Juans.


...Pacific Northwest/Northern Rockies...
Day 3...

Troughing over Alaska today will steadily move southeastward along
the BC coast Tuesday, bringing a 105kt jet into western WA. A
modest surge of moisture along/ahead of the cold front (IVT values
around the 90th percentile for mid-April) will support widespread
rain and mountain snow starting around early Tuesday and continuing
into Wednesday. Snow levels initially around 3000ft (Cascades) to
4000ft (Northern Rockies) will fall to around 1500-2000ft in the
Cascades as much colder air works in from the northwest by 12Z
Wednesday (700mb temperatures dropping to around -10C to -14C) as
the cold front reaches the Cascades. This will bring snow to the
passes, though perhaps starting as rain in the lower passes, which
could be significant at higher passes. Through 12Z Wednesday, WPC
probabilities for at least 6 inches of snow are >50% above about
2500ft in the Cascades and 5000-6000ft in the Northern Rockies.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso


$$

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FOUS11 KWBC 121806
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
206 PM EDT Sun Apr 12 2026

Valid 00Z Mon Apr 13 2026 - 00Z Thu Apr 16 2026

...Northern/Central Rockies...
Days 1-2...

An approaching upper trough and broad southwesterly flow will
allow light to moderate snow to spread across the Great Basin and
northern Rockies tonight through the day on Monday. By Tuesday,
trailing vorticity on the southwest side of this trough will move
into the Four Corners, enhancing snowfall more broadly over the CO
Rockies, including the Wasatch, Uintas, and especially the San
Juans in southwest CO. Snow levels initially around 8000-9000ft
will fall to around 7500ft by later Tuesday and early Wednesday as
most of the snow ends from west to east. WPC probabilities for at
least 6 inches of snow are >50% above about 8000ft over eastern OR
into the central ID ranges due to the lead upper trough into
Monday, and above 10,000-11,000ft into the Wasatch, Uintas, and San
Juans.


...Pacific Northwest/Northern Rockies...
Day 2-3...

Initial troughing over Alaska will steadily move southeastward
along the BC coast through Tuesday, bringing a 105kt jet into
western WA. A modest surge of moisture along/ahead of the cold
front (IVT values around the 90th percentile for mid-April) will
support widespread rain and mountain snow starting around early
Tuesday and continuing into Wednesday. Snow levels initially around
3000ft (Cascades) to 4000ft (Northern Rockies) will fall to around
1500-2000ft in the Cascades as much colder air works in from the
northwest by 12Z Wednesday and especially by 00Z Thursday (700mb
temperatures dropping to around -15C). Though precipitation may
start as rain, snow will quickly become the dominant p-type for
most passes. Some of this snow could even become significant at
higher passes, including Snoqualmie Pass and Washington Pass.
Through 00Z Thursday, WPC probabilities for at least 6 inches of
snow are >50% above about 2500ft in the Cascades and 5000-6000ft in
the Northern Rockies.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso/Miller





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FOUS11 KWBC 130711
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
311 AM EDT Mon Apr 13 2026

Valid 12Z Mon Apr 13 2026 - 12Z Thu Apr 16 2026

...Sierra to the Rockies...
Days 1-2...

Lead upper trough over the Great Basin will briefly close off and
continue northeastward then eastward, spreading snow over the
northern Great Basin into Idaho and Montana/Wyoming. Accumulations
will generally be light.Trailing vorticity on the southwest side of
the lead trough will close off into an upper low over SoCal this
morning and move eastward. This will bring another round of snow to
the central/southern Sierra this afternoon/evening with light to
modest accumulation of a few inches to perhaps 6-8 inches at the
highest peaks. Tonight into tomorrow, this upper low will move into
the Four Corners region, enhancing snowfall more broadly over the
Wasatch, Uintas, and especially the San Juans in southwest CO. Snow
levels initially around 8000-9000ft will fall to around 7500ft by
later Tuesday and early Wednesday as most of the snow ends from
west to east. WPC probabilities for at least 6 inches of snow are

50% above about 8000ft over eastern OR into the central ID ranges,

and above 10,000-11,000ft into the Wasatch, Uintas, and San Juans.


...Pacific Northwest/Northern Rockies...
Day 2-3...

Initial troughing over Alaska will steadily move southeastward
along the BC coast through Tuesday, bringing a 105kt jet into
western WA. A modest surge of moisture along/ahead of the cold
front (IVT values around the 90th percentile for mid-April) will
support widespread rain and mountain snow across the Cascades
starting around early Tuesday, becoming heavy Tuesday
afternoon/evening, and continuing as lighter snow into Wednesday.
Snow will spread eastward across the Northern Rockies Tuesday night
and into Wyoming by Wednesday. Snow levels initially around 3000ft
(Cascades) to 4000ft (Northern Rockies) will fall to around
1500-2000ft in the Cascades as much colder air works in from the
northwest by 12Z Wednesday and especially by 00Z Thursday (700mb
temperatures dropping to around -15C). Though precipitation may
start as rain, snow will quicklybecome the dominant p-type for most
passes. Some of this snow could even become significant at higher
passes, including Snoqualmie Pass and Washington Pass. By 12
Thursday, the upper trough will move inland, just past the
Cascades, ending snow from west to east just after the end of this
forecast period. Through 12Z Thursday, WPC probabilities for at
least 6 inches of snow are >50% above about 2500ft in the Cascades
and 5000-6000ft in the Northern Rockies. Probabilities for at least
a foot of snow are >50% above 3000-3500ft in the Cascades and
6000-7000ft in the Northern Rockies.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso/Miller



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FOUS11 KWBC 131838
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
238 PM EDT Mon Apr 13 2026

Valid 00Z Tue Apr 14 2026 - 00Z Fri Apr 17 2026

...Central Rockies...
Day 1...

Closed mid-level low emerging from the Great Basin will open into
an amplified, but positively tilted, trough as it ejects into the
Central Rockies by Tuesday evening. This will lead to a period of
enhanced lift through divergence and height falls, with the LFQ of
an accompanying upper jet streak helping to produce cyclogenesis in
the lee of the CO Rockies Tuesday aftn. Mid-level Pacific moisture
on the 700-500mb SW flow will increase column PWs to +1 to +2 sigma
across CO, with some additional low-level moisture becoming
available late D1 as cyclonic flow around the developing cyclone
creates E/NE winds from the Central Plains to advect additional
moisture westward from the Gulf moisture return. This moisture
being acted upon by the increased synoptic lift (and some upslope
flow on the low-level E/NE winds) will create periods of moderate
precipitation Tuesday, with significant snow accumulations expected
above generally 7000-8000 ft. WPC probabilities D1 are moderate to
high (50-90%) for 6+ inches across the Wasatch, San Juans, and CO
Rockies, with locally 12+ inches possible (30-50%) across the San
Juans before precip winds down very late Tuesday night as the
surface low pulls away to the east.


...Pacific Northwest through the Northern Rockies...
Days 1-3...

An increasingly active week of winter weather will begin today,
with widespread snowfall expected across most of the terrain from
the Pacific Northwest through the Northern Rockies.

The period begins with an amplified/closed low over southeast
Alaska dropping steadily southward to reach the British Columbia
coast by 00Z/Wed, and then pivot onshore WA/OR before 00Z/Thu. This
evolution will not only produce impressive height falls for ascent,
but also pinch the downstream flow to help surge Pacific moisture
into the region. This is reflected by IVT for which both the ECENS
and GEFS indicate has a >90% chance for exceeding 250 kg/m/s, with
the West-WRF indicating a narrow corridor of 500+ IVT surging
onshore as well. This IVT will be driven rapidly eastward beneath a
zonally oriented jet streak amplifying south of the upper low,
combined with intensifying SW low-level flow driving WAA ahead of a
surface cold front. Together, this will push PWs to +1-+2 sigma,
although the coverage of these highest PWs will be somewhat
confined to a narrow channel ahead of the cold front.

As this moisture spreads east and is acted upon by the robust
ascent, the result will be an expanding shield of precipitation,
with locally heavier precipitation expected in the higher terrain
where upslope enhancement is likely. Snow levels will vary widely
through the event, but are expected to generally fall D2/D3 behind
the cold front and the parent trough driving it southeast.

On D1, the heaviest accumulations are likely confined to the
Cascades as the event begins, which is reflected by WPC
probabilities for 6+ inches of snow above 50% focused in the WA
Cascades and Olympics, and generally above 4000 ft. During D2, the
coverage of heavy snow expands considerably as the front and
accompanying synoptic ascent shift east in tandem with the core of
the IVT moving inland. This results in WPC probabilities for 6+
inches being above 50% from the Olympics, along the WA and OR
Cascades, and eastward into the Blue Mountain, Sawtooth/Salmon
River, and much of the Northern Rockies. Snow levels in the Rockies
will fall from around 6000 ft to 4000 ft, but will crash well below
pass levels, as low as 2500 ft, in the Cascades, leading to
hazardous pass-travel. Finally, during D3 the snowfall will wane
across the Cascades but continue to expand eastward as far as the
Absarokas, Tetons, and Wind Rivers, while continuing across much
of the rest of the Northern Rockies. Snow levels D3 fall to
3000-4000 ft in these areas, with WPC probabilities suggesting a
70+% chance of at least another 6 inches of snow. Storm total
snowfall during this event will be considerable, forecast to reach
1-3 feet in the higher elevations.

Additionally, as the cold front sweeps southeast Wednesday night
and Thursday, it will be accompanied by a line of heavier
precipitation as low-level RH, 0-2km fgen, and 0-2km CAPE
maximize. The simulated reflectivity from the available guidance
suggests there will be a line of precip with embedded heavier
rates, and the snow squall parameter rises above 1. While the setup
is not ideal, and we are past the climatological favored period for
snow squalls, this setup does suggest the potential for convective
snow showers or snow squalls across the area. Additional snowfall
from any showers/squalls will be limited, but briefly heavy rates
and gusty winds could cause hazardous travel. This will need to be
monitored as we approach the high-res guidance windows to get a
better understanding of the timing, placement, and risk, of any
snow squalls.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.


Weiss


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FOUS11 KWBC 140755
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
355 AM EDT Tue Apr 14 2026

Valid 12Z Tue Apr 14 2026 - 12Z Fri Apr 17 2026

...CO Rockies...
Day 1...

Upper low over southwestern UT this morning will move eastward and
weaken slightly into a strong trough as it enters the CO Rockies
this evening. SW flow will help bring in some moisture to the
region which will wring out light to moderate snow over the
Rockies. Snow levels will be around 7500-8000ft, so any significant accumulations of at least 6 inches are >50% above about 10,000ft.


...Pacific Northwest through the Northern Rockies...
Days 1-3...

Active wintry pattern from the Pacific Northwest through the
Northern Rockies starts today. A strong upper low moving
southeastward along the BC coast will dive into western WA tomorrow
evening and past the Divide Thursday evening. The upper low will
split into two pieces -- the northern portion will continue
eastward as a weakly closed upper low while the southern portion
will sink farther south into the Great Basin. Though moisture will
be rather limited (just a narrow surge of moisture ahead of the
cold front), heights and mid/lower-level temperatures will be well
below average and below the 1st percentile for this time of year,
reminiscent of a mid-winter system.

Rain and mountain snow will precede the cold front today with
initial snow levels around 3500-5000ft along the Cascades and
5000-6000ft over the Northern Rockies. Snow will increase later
this afternoon and tonight via upslope enhancement with rates of
1-3"/hr possible in the higher elevations, generally above the
passes. Cold front should push through the WA Cascades early
Wednesday which will push the heavier snow rates southward to stay
just ahead of the front into the OR Cascades. Snow levels will fall
to around 1000-1500ft tomorrow morning behind the front as snow
lightens. However, the upper low will then swing through with its
cold core and additional snow to around 1500-2000ft during the
afternoon hours. To the east, snow will increase over the Northern
Rockies where the cold front will take nearly a day longer to reach
past the Divide. There, too, snow levels will fall sharply behind
the front down to below 2000ft (i.e, all valley floors) where at
least some accumulation is probable. On Thursday
afternoon/overnight, the upper low will move through the Northern
Rockies with additional light to moderate snow mainly over SW MT
southward. Through 12Z Friday, with the strongest height falls over
northern UT into WY, snow will be favored over the northern
Wasatch/Unitas but especially into Wyoming (Bighorns) as it ends
over the Pacific Northwest.

WPC probabilities for at least 6 inches of snow are >50% above
about 2000-3000ft in the Cascades, 4000ft in the Northern Rockies,
and 7000ft in Wyoming. For at least a foot of snow, WPC
probabilities are >50% above about 3000-4000ft in the Cascades
(this includes Snoqualmie Pass), 5000-6500ft in the Northern
Rockies, and 9000-10,000ft in Wyoming. Total accumulations may
range from 1-3ft in the region, along with windy conditions, making
for very difficult to impossible travel through the terrain.

Additionally, the combination of the sharp cold front and well
below normal mid-level temperatures could yield some snow squalls
or at least some convective snow along/ahead of the front Thursday,
despite it being April (outside the more typical period). This
could cause short-lived but impactful drops in visibility and
hazardous travel.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso


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FOUS11 KWBC 142027
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
427 PM EDT Tue Apr 14 2026

Valid 00Z Wed Apr 15 2026 - 00Z Sat Apr 18 2026


...Cascades...
Days 1-2...

A low pressure system currently centered over Southeast Alaska (aka
the Alaska Panhandle) will shift SE to central WA through Wednesday
before opening into a split trough with a portion that digs down
the Rockies through Friday and one that drifts east over the
southern Canadian Prairies. Pacific moisture is somewhat limited,
but the cold aspects of the system will make it reminiscent of a
mid-winter system.

Snow levels starting around 3500ft on the WA Cascades quickly drop
to 1000ft or less late this evening as the associated strong cold
front pushes through. The heavier snow rates will stay just ahead
of the front that works its way down the OR Cascades Wednesday. A
round of more moderate snow rates arrives to the WA Cascades with
the upper low center Wednesday afternoon. Snow levels bump up to
around 1500ft through this time before Cascades snow tapers off
Wednesday night.

Day 1 snow probs for >8" are 50-90% along the Cascades above about
2500ft including Snoqualmie and Santiam Passes. Winter Storm
Warnings remain in effect through the range. Day 2 snow probs for

4" are generally 30-50% for the central WA Cascades and

northern/central OR Cascades.


...North to Central Rockies and central High Plains...
Days 1-3...

Moisture shifts east across the Cascades through the northern
Rockies tonight through Wednesday before the plume settles over
northwest Wyoming Wednesday night into Thursday. The southern
portion of the trough drives expanding precip and a low level
upslope component to the CO Rockies and adjacent High Plains
Friday.

The cold front reaches northwest MT Wednesday morning with a
gradual progression to Wyoming through Wednesday night. Snow levels
ahead of the cold front are 5000-6000ft over MT before dropping to
2000-3000ft behind the front as rates decrease. Snow levels over WY
rise to 8000ft in the warm sector Wednesday before dropping to
3000ft Wednesday night behind the front. Snow levels around 9000ft
in CO on Thursday drop to 4000-5000ft through the day Friday.

Day 1.5 WPC snow probs for >8" are 40-80% for all western MT and central/northern ID ranges. Day 2 snow probs for >8" are 50-80% for
the Absarokas, Tetons, and the Wind River Range. Then Day 3 probs
for >6" are 40-80% for the Bighorns, Wind River again, and southern
WY through northern CO Ranges as well as the Uinta and higher
Wasatch in UT.

As a final note, the sharp cold front should produce snow squalls
or convective snow bands along/ahead of it Wednesday and Thursday.
This activity could cause short- lived but impactful drops in
visibility and hazardous travel.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.


Jackson



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FOUS11 KWBC 150653
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
253 AM EDT Wed Apr 15 2026

Valid 12Z Wed Apr 15 2026 - 12Z Sat Apr 18 2026


...Cascades...
Day 1...

Strong upper low approaching Vancouver Island this morning will
continue southeastward today, with a lead cold front moving through
the WA Cascades. The heaviest snowfall will be just ahead of the
cold front this morning from the southern WA Cascades into the OR
Cascades. Snow levels will fall from 3500ft ahead of the front to
1000-1500ft behind the front as snow briefly lightens. The trailing
upper low will bring in more light to moderate snow for the region
this afternoon/evening and this will gradually end by tomorrow
morning. WPC probabilities for an additional 6 inches of snow are

50% above about 2000-2500ft.

...North to Central Rockies and central High Plains...
Days 1-3...

The upper low will cross the Divide on Thursday and split into two
pieces -- the northern portion will continue eastward along the
Canadian border as a weakly closed low while the southern portion
digs through the Great Basin before turning east to the central
Rockies. This will spread snow over much of the region as colder
winter-like air ushers in behind the cold front. With the SW flow
aloft, the central ID ranges, SW MT, and WY ranges will be the
focus for the heaviest snow. By Friday, height falls reach the
western High Plains where a low-level upslope component to the CO
Rockies and adjacent High Plains will promote additional snowfall
in the wake of the cold front. All snow will end around 12Z
Saturday as the trough continues steadily through the Plains to the
Upper Midwest.

For the Northern Rockies, the cold front will reach northwest MT
Wednesday morning with a gradual progression to Wyoming through
Wednesday night. The cold air behind the front is impressive (700mb
temps -12 to -16C) which will plunge temperatures 25-35 degrees
pre- to post-FROPA. Snow levels ahead of the cold front will be
around 5000-6000ft over MT before dropping to 2000-3000ft behind
the front as rates decrease. Snow levels over WY rise to 8000ft in
the warm sector Wednesday before dropping to 3000ft Wednesday night
behind the front. Snow levels around 9000ft in CO on Thursday drop
to 4000-5000ft through the day Friday.

WPC probabilities for at least 8 inches of snow are >50% above
about 5000ft in northern ID/northwest MT and 6000ft in the central
ID ranges. Over southwest MT (Absarokas) to the Tetons, Wind River
Range, and Bighorns, WPC probabilities for at least 8 inches of
snow are >50% above about 7000-9000ft from northwest to southeast.
Over UT into CO, amounts will generally be lighter but at least 6
inches of snow is likely (>50% chance) above about 9000ft. Lighter
amounts (1-2") are expected along/east of the Front Range into
metro Denver as rain turns to snow Friday evening.

As a final note, the sharp cold front should produce snow squalls
or convective snow bands along/ahead of it today and Thursday. This
activity could cause short-lived but impactful drops in visibility
and hazardous travel.


The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.


Fracasso


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FOUS11 KWBC 151905
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
305 PM EDT Wed Apr 15 2026

Valid 00Z Thu Apr 16 2026 - 00Z Sun Apr 19 2026


...Cascades...
Day 1...

Potent mid-level low drops over Washington State through this
evening with the leading cold front currently over OR pushing into
northern CA this afternoon. Instability showers in onshore flow
brings snow for the central WA Cascades south through the OR
Cascades into Thursday morning where Day 1 snow probs for >4" are
40-80% above the snow level that drops to around 1500ft through the
rest of this afternoon.


...North to Central Rockies and Central High Plains...
Days 1-2...

The mid-level low opens into a trough over the northern Rockies
early Thursday with a northern portion shifting east along the
Canadian border as a weakly closed low while the southern portion
digs through the Great Basin before turning east across the
central Rockies Friday. The preceding cold front provides a focus
for snow over central ID terrain this afternoon, shifting to
southern ID/western WY tonight. Snow levels of 6000-7000ft MSL
ahead of the front rapidly drop to 2000-3000ft (subterranean)
behind the front. Day 1 snow probs for >6" are 40-80% in central ID
(values reduced since the probs start at 00Z in ongoing snow) and
50-90% in terrain around greater Yellowstone including the Tetons
and Absarokas as well as the Wind River Range. The progression of
the front and southern lobe of the split trough through Thursday
night brings Day 1.5 snow probs for >6" to 60-90% for the Bighorns
and 40-70% for the Wasatch and Uinta.

The mid-level trough crosses CO on Friday providing much welcome
snow to western slopes of the northern/central CO Rockies. Day 2
snow probs for >6" are 40-70% for the Park and Front Ranges.
Northerly post-frontal flow brings a light snow risk to the Denver
metro Friday afternoon where Day 2 snow probs for >2" are 10-20%
for the northern side of the Palmer Divide into the foothills west
of Denver.

An additional note, the sharp cold front should produce
convective snow bands over eastern OR/central ID this afternoon and
southern UT into central WY Thursday afternoon. These may be strong
enough to qualify as snow squalls and cause hazardous drops in
visibility and flash freeze conditions on roads.


...Northern Plains...
Day 2...

The strong cold front associated with the low moving over the
Pacific Northwest this afternoon will push onto the northern Plains
Thursday. As the upper trough splits and digs down the Great Basin
Thursday night, a tightening baroclinic zone with enhanced SW flow
overhead with moisture from the southern Plains/Gulf will allow
snow bands to set up first over the Black Hills/western SD Thursday
evening and over eastern ND/northwest MN late Thursday night into
Friday. Marginal thermals look to be overcome in potent banding
from low level fgen forcing with moderate precip rates. 12Z
HRRR/3kmNAM in agreement for a subfreezing profile in the banding
with potential for a few inches of snow. Day 2 snow probs for >2"
are 40-60% from central to northeastern ND and the northwest corner
of MN. To the east of this snow swath is a risk for ice accretion
should the 2m temp remain below freezing. Day 2 ice probs for >0.1"
are 10-20% in northeast ND and across northwest MN.



Jackson



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FOUS11 KWBC 160756
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
356 AM EDT Thu Apr 16 2026

Valid 12Z Thu Apr 16 2026 - 12Z Sun Apr 19 2026


...North to Central Rockies and Central High Plains...
Days 1-2...

Shortwave trough moving across the interior Northwest will amplify
as it traverses into the Rockies, with 500-700mb heights falling
to between the 1st and 10th percentiles of the CFSR climatology.
This feature will remain generally progressive despite the
amplification, leading to broad but impressive ascent through
height falls/PVA combined with jet-level diffluence (with some
coupling noted over the Central Rockies leading to lee
cyclogenesis/surface low development.

Moisture will increase modestly, primarily in the 500-700mb layer
as streamlines suggest Pacific flow downstream of the primary
trough axis leading to elevated specific humidity in the mid-levels
despite TPWs remaining near-normal. Where the broad synoptic ascent
overlaps the greatest mid-level moisture, precipitation will
overspread the region, generally falling as light to moderate snow
above 6000 ft, at least initially. However, these snow levels will
fall to as low as 2000-3000 ft behind a sharp cold front which will
traverse E/SE beneath the primary trough, with upslope flow into
terrain and steep lapse rates beneath this cold core leading to
enhanced ascent and locally even lower snow levels at times.

Since this system remains progressive, total snowfall will be
somewhat modest, but locally much heavier accumulations are likely,
especially in the WY/CO terrain where some easterly low-level flow
around the developing surface low will enhance moisture and ascent.
2-day WPC probabilities indicate the heaviest snowfall will occur
across the higher elevations from the Absarokas into the Wind
Rivers, Big Horns, Laramies, Park Range of CO, and Front Range. In
these areas, the probability of at least 8 inches of snow is
between 50-90%, with locally more than 12 inches possible (30-50%)
across the Big Horns. Lighter snows (up to 4") are likely into the
High Plains of WY and CO, including along the Palmer Divide.

Additionally, snow squalls continue to appear possible along the
cold front, especially across parts of NV, UT, and WY today. While
snow accumulations from any squalls will be minimal, briefly heavy
snow rates and gusty winds could create dangerous travel.


...Northern Plains...
Days 1-2...

The strong cold front moving through the Central Rockies and High
Plains Thursday into Friday will continue eastward, reaching the
Northern Plains by Friday morning. Behind this front, the upper
trough will split, with a closed northern stream impulse moving
along the ND/Canada border on Friday, while secondary jet energy
lifts into the Upper Mississippi Valley to help drive ascent. The
overlap of the low-level baroclinic zone and this jet evolution
will result in impressive mid-level fgen acting upon a modestly
moistening column to produce a stripe of heavy precipitation.
Forecast profiles indicate that the low-level thermal structure
will be marginally favorable for snow, but the strong ascent into
(or just above) the DGZ will help dynamically cool the column to
result periods of heavy snowfall rates which could reach 1-2"/hr
at times as reflected by the WPC prototype snowband tool. With most
of this occurring before daybreak Friday, the snow could
accumulate efficiently during p-type changeover, and WPC
probabilities indicate a low risk (10-30% chance) of 4+ inches of
snow within this band, especially in parts of ND. Farther east,
some light mixed precipitation is also possible, reflected by WPC
probabilities that rise to 50-70% for at least 0.01" of ice for
parts of NW MN.


Weiss


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FOUS11 KWBC 161951
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
351 PM EDT Thu Apr 16 2026

Valid 00Z Fri Apr 17 2026 - 00Z Mon Apr 20 2026


...North and Central Rockies through the Northern Plains...
Day 1...

Mid-level trough axis over the northern Great Basin will dig
southeast to CO through Friday while a separate low over the
northern MT border will continue to track east to Winnipeg. Broad
ascent will persist ahead of these troughs which will enhance an
already tight baroclinic zone over the Dakotas tonight. Low level
moisture will continue to stream up the Plains tonight while
elevated Pacific moisture streams over the Rockies ahead of the
progressive cold front.

Some snow squalls/convective bands will continue to be possible
over UT/WY into this evening with the overall focus for snow on
terrain, shifting over CO through Friday.

Day 1 snow probs for >6" after 00Z are 40-60% in west-central MT
ranges, the highest areas around Yellowstone, around 70% on the
length of the Bighorns and 40-60% over southern WY/north and
central CO Ranges.

Jet energy east of the border low lifts over the Northern Plains
tonight which will overlap with the low-level baroclinic zone from
the front. Strong mid- level fgen acting upon a modestly
moistening column will produce a stripe of heavy banding from
western SD through central/eastern ND overnight. Snow becomes more
likely through the night with nocturnal trends and increasing
precip rates. A warm nose will also lead to some mixed precip near
the ND/MN border late tonight/early Friday. Day 1 snow probs for

4" are now 10-20% over central ND (a bit of a west shift from

overnight). Day 1 ice probs for >0.1" are 10-30% over northeast ND
through northwest MN.


Jackson


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FOUS11 KWBC 170709
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
309 AM EDT Fri Apr 17 2026

Valid 12Z Fri Apr 17 2026 - 12Z Mon Apr 20 2026


...North and Central Rockies through the Northern Plains...
Day 1...

De-ampifying shortwave trough will pivot E/NE across the Central
Rockies and Northern Plains through Saturday morning. Broad ascent
ahead of this trough (through a combination of height falls and
PVA) will interact with modest upper level diffluence within the
RRQ of a meridionally arcing, but weakening, jet streak. At the
surface, a cold front surging eastward will provide additional
ascent through convergence, with mid-level fgen in its wake
providing a focus for heavier precipitation as well.

Moisture will remain elevated through this evening thanks to a
combination of Pacific moisture streaming over the Rockies on broad
SW mid-level flow and southerly flow out of the Gulf lifting into
the Plains.

This will result in two axes of precipitation: lingering fgen mixed rain/snow/freezing rain in the Northern Plains, and continued light
to moderate snow across the Central Rockies. The heaviest snow and
ice in the Northern Plains is expected before 12Z, but residual
light freezing rain/snow through this aftn could result in light
accumulations of snow (less than 2 additional inches) and freezing
rain (less than 0.05 inches) from NW MN through the Arrowhead.
Farther south into the Central Rockies, especially in the higher
elevations of CO including the Park Range and Front Range, WPC
probabilities for 4+ inches of snow remain elevated at 50-70%
through D1 before precip shuts off tonight.


...Upstate New York/Northern New England...
Day 3...

A strong cold front will cross from Upstate NY Sunday morning to
well of the Atlantic Coast by Monday morning. A narrow corridor of
robust warm and moist advection ahead of this front will bring
periods of rain to New England, but as the the cold front races
east, temperatures will crash dramatically behind it. While this
front will also cause rapid drying of the column, there appears to
be enough of a residual SW flow in the mid-levels to allow for
anafrontal precipitation to continue, which will fall as snow in
the higher elevations of Upstate NY (in the Adirondacks) as well as
the Greens of VT, Whites of NH, and mountains of interior
western/northern ME. While snowfall accumulations should be
generally modest, a few inches of snowfall is possible as reflected
by WPC probabilities indicating a 10-30% chance of 4+ inches in
these higher elevation regions.


Weiss



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