FOUS11 KWBC 131821
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
221 PM EDT Fri Mar 13 2026

Valid 12Z Fri Mar 13 2026 - 12Z Mon Mar 16 2026

...Northern High Plains through the Upper Midwest...
Days 1-3...

...Blizzard likely this weekend with widespread major impacts and record-breaking snowfall for portions of the Upper Midwest and=20
Great Lakes...

Guidance is consolidating around a rapidly strengthening low which
will develop in the lee of the Rockies Saturday and then track=20
east through Sunday to the Mississippi Valley, then turn northeast=20
Monday before occluding and then exiting. While the primary low is
going to be the one that brings the most substantial impacts, this
system will, in reality, driven by two distinct surface lows=20
embedded within the amplifying mid-level pattern and accompanying=20
coupled jet streaks.

The event really has already begun across the High Plains of
Montana as moisture streaming onshore within an impressive IVT=20
plume (atmospheric river) continues to push well inland leading to=20
a surge in PW/column moisture across the northern Plains. The=20
accompanying upper jet streak arcing zonally across the region=20
working in tandem with a surface stationary front will cause=20
snowfall to continue to spread ESE-ward. Overall ascent during D1=20
across this area appears modest as noted by omega fields and=20
regional soundings, but the impressive PW anomalies (nearing +2=20
sigma) will support periods of moderate snowfall from MT through=20
parts of SD. The heaviest accumulations are likely in the higher=20
terrain, with otherwise modest accumulations expected D1. Where the
heaviest snow occurs, generally just east of the Continental=20
Divide, WPC probabilities are high (>70%) for at least 4 inches of=20
snow for much of central and southern MT, with locally more than 8=20
inches possible in the Little Belt range.

The more significant portion of this event begins Saturday as lee=20 cyclogenesis begins in more impressive fashion east of CO/WY. A=20
shortwave digging onshore the British Columbia coast tonight will=20
begin to amplify as it digs into the Central Rockies Saturday=20
night. The rapid amplification of this shortwave will drive=20
impressive height falls downstream, with impressive jet streak=20 intensification occurring as a result. The overlap of height falls=20
with this jet development will lead to a rapidly deepening surface=20
low tracking from CO to IA before 12Z Sunday. As the jet begins to=20
kink southward, it will continue to produce heavy snow, with an=20
expansion across MT due to mid-level divergence downstream of the=20 approaching shortwave. At this time the snowfall rates should=20
become more intense through 00Z/Sun across MT, with additional=20
snowfall of 4+ inches possible (50-70%) for much of the eastern=20
half of the state.

After 00Z Sunday is when this event truly becomes a major winter
event with widespread considerable impacts. As the surface low
continues east from the Central Plains it will encounter dual=20
moisture streams, one from the decaying AR pushing east, and a=20
second as the theta-e ridge begins to arc northward on intensifying WAA/southerly flow out of the Gulf. The overlap of robust deep=20
layer ascent with maximizing moisture return will deepen the low=20 substantially, and help expand a considerable precipitation shield,
with heavy snow arcing from SD through the Great Lakes by Sunday
morning, and then slowly pivoting northeast while continuing=20
through D3 as the surface low moves into Ontario by 00Z/Tuesday.

The synoptic setup is extremely favorable for a classic Midwest
winter storm with widespread intense snowfall. Embedded bands=20
with snowfall rates of 1-3"/hr are expected as reflected by high=20
potential for CSI and even CI in model cross-sections Sunday aftn=20
into Monday which drives intense omega into the TROWAL. Although=20
guidance has trended north, there is high confidence in a=20
laterally translating band of heavy snow from SD into MN Sunday=20
morning, with the environment transiting into one that matches the=20 conceptual model for a pivoting band over eastern MN and WI Sunday=20
evening into Monday, It is in this area where the heaviest snowfall
is expected, and potentially record, or near- record 2-day=20
snowfall is possible from eastern MN through WI and northern MI.=20
Elsewhere, snowfall rates of 1"/hr or more are still likely at=20
times, just with lesser duration. These snowfall rates combined=20
with gusty winds reaching up to 60 mph will create blizzard and=20
near- blizzard conditions and whiteouts, with major to extreme=20
impacts progged by the recent WSSI-P. Even in areas that get lower=20
snow totals, the blowing snow potential will still result in=20
difficult travel, and it is likely that most forms of=20
transportation will be treacherous at best, and impossible at=20
worst, through the event across a large area from Montana to
Michigan, and everywhere in between.

2-day WPC probabilities ending 12Z Monday are impressive, and
suggest a high likelihood (>70%) for at least 12 inches from the
Buffalo Ridge eastward through the Twin Cities, across much of WI,
and through all of the U.P. of MI. Within this axis, WPC
probabilities for at least 24" are already above 50%, and some
locations may approach 3 feet before the event winds down Tuesday.
Outside of this axis of heaviest snow, a broad swath of at least 6
inches is likely (>70%) from far western SD through central IA and
northeast into central MI. Similarly impressive, the 07Z NBM 5%
probabilities (meaning a 95% chance of seeing more), show amounts
over a foot from Central Wisconsin around Wausau east to north of
Green Bay, along the north shore of Lake Michigan over to the=20
Straits of Mackinac.

Finally, on the S/SE side of this snowfall swath, an axis of mixed precipitation is likely, leading to icing accretion from central IA
through southeast WI and into lower MI. The most significant icing
is expected for lower MI where WPC probabilities for at least 0.25"
of ice are between 30-50%.

This storm could result in record snowfall in some places, and=20
with SLRs being slightly below climo, combined with the strong=20
winds, power outages and long-lasting impacts are expected. For=20
these reasons, Winter storm key messages are in effect, and are=20
linked below (Key Message 1).


...Cascades Through The Northern Rockies...=20
Day 1...

...Washington Cascades Major Winter Storm continues today...

An atmospheric river (AR) will wane tonight as an area of IVT with
around 500 kg/m/s continues to advect inland into the Pacific
Northwest and weakens. This AR will sink south into Oregon and
weaken overnight. Associated moisture already inland over the=20
Northern Rockies will continue the heavy snow into tonight,
tapering off from west to east.

There is high confidence in heavy snow tonight across the Northern
Rockies before precipitation wanes on Saturday with much lighter=20
snow. The more challenging aspect is what will happen with snow=20
levels across the region. As a surface cold front digs south in=20
conjunction with an upper level shortwave, snow levels will crash=20
across the Oregon Cascades and Idaho Panhandle, but with much=20
lighter precipitation during that transition in Oregon. In Idaho
and points south and east, the moisture will be slower to exit (as
there will be more of it as remnants of the A.R. This suggests=20
that considerable impacts will continue at the higher elevations of
the Northern Rockies, with lesser snowfall and impacts expected=20
across the Oregon Cascades.

This is reflected by WPC probabilities that show at least 4 inches
of additional snowfall D1 in the Blue Mountains, the Bitterroots,=20
the higher elevations of NW WY near Yellowstone NP, and the=20
Sawtooth/Salmon River ranges. By Saturday, snowfall persisting=20
across the Cascades wanes rapidly leaving just light additional=20 accumulations, but heavy snow will continue across the Wind Rivers,
Absarokas, Tetons, Big Horns, and other neighboring terrain where=20
WPC probabilities predict a high risk (>70%) for 8+ inches of snow.


...Great Lakes into the Northeast...
Day 1...

Intense but compact low pressure will continue crossing the Great=20
Lakes into the Northeast tonight and Saturday, bringing blizzard=20
and near-blizzard conditions to many areas. This low is being=20
driven by a potent but progressive shortwave which is progged to=20
continue driving northeast off the coast of Maine by Saturday
afternoon. The accompanying surface low over MI will picks up=20
speed and race east into New England Saturday before exiting into=20
the Canadian Maritimes.

As the low moves into the Northeast tonight, resurgence of WAA=20
will expand precipitation into New England, and a secondary low may
develop near the coast of ME Saturday morning. Total forcing for=20
ascent and available moisture will likely be less than areas=20
upstream (in the Great Lakes), but periods of heavy snow both=20
within WAA and along an inverted trough/occluded front upstream=20
from the secondary low pressure will result in areas of heavy=20
snowfall with rates again potentially reaching 1"/hr. WPC=20
probabilities across the Northeast are as high as 80% for 4+ inches
in the Tug Hill and southern Adirondacks, with probabilities=20
reaching 40-60% for the Chautauqua Ridge, and parts of the higher=20
terrain of VT/NH/ME. A local maxima is also possible along the=20
coast and interior mountains of ME where onshore flow ahead of the
secondary low pressure advects higher moisture onshore.

Wegman/Weiss


...Winter Storm Key Messages are in effect for the blizzard into
the upper Midwest and Great Lakes this weekend through Monday.=20
Please see current Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late= stKeyMessage_1.png__;!!DZ3fjg!_NSB2DTD1F6imMymt-Wtj7XgWd7Pbh0hsQzO2XVi3KNqk= 7rI7-GBiAMUd83G1GtCUJp3CRKMXwQzEqolYjJXAQXfpe4$=20



$$

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FOUS11 KWBC 140728
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
328 AM EDT Sat Mar 14 2026

Valid 12Z Sat Mar 14 2026 - 12Z Tue Mar 17 2026

...Northern High Plains through the Great Lakes...=20
Days 1-3...

...Blizzard likely this weekend with widespread major impacts and record-breaking snowfall for portions of the Upper Midwest and=20
Great Lakes...

Confidence continues to be high in a widespread major winter storm
from the Northern Plains through the Upper Midwest and Great Lakes
as a lee surface low lifts northeast and rapidly deepens into an
increasingly moist column. While it is this lee cyclone that will
be responsible for the most significant impacts, this event is
really two-pronged with the first event already ongoing across the
Northern High Plains.

Across the High Plains of Montana, moisture continues to stream
onshore within an impressive IVT plume (atmospheric river)=20
pushing well inland leading to a surge in PW/column moisture=20
across the northern Plains. The accompanying upper jet streak=20
arcing zonally across the region working in tandem with a surface=20
stationary front will cause snowfall to continue to spread ESE-=20
ward. Overall ascent during D1 across this area appears modest as=20
noted by omega fields and regional soundings, but the impressive PW
anomalies (nearing +2 sigma) will support periods of moderate=20
snowfall from MT through parts of SD. The heaviest accumulations=20
are likely in the higher terrain, with lower accumulations expected
elsewhere across the High Plains today. Where the heaviest snow=20
occurs, generally just east of the Continental Divide, WPC
probabilities are high (>70%) for at least an additional 4" of
snowfall through tonight, with more than 8" possible in the higher
elevations around the Little Belts.

The more significant portion of this event begins this afternoon=20
as lee cyclogenesis begins in more impressive fashion east of=20
CO/WY. A shortwave digging onshore the British Columbia coast=20
tonight will begin to amplify as it digs into the Central Rockies=20
Saturday night. The rapid amplification of this shortwave will=20
drive impressive height falls downstream, with impressive jet=20
streak intensification occurring as a result. The overlap of height
falls with this jet development will lead to a rapidly deepening=20
surface low tracking from CO to IA before 12Z Sunday.=20

After 00Z Sunday is when this event truly becomes a major winter
event with widespread considerable impacts. As the surface low
continues east from the Central Plains it will encounter dual=20
moisture streams, one from the decaying AR pushing east, and a=20
second as the theta-e ridge begins to arc northward on intensifying WAA/southerly flow out of the Gulf. The overlap of robust deep=20
layer ascent with maximizing moisture return will deepen the low=20 substantially, and help expand a considerable precipitation shield,
with heavy snow arcing from SD through the Great Lakes by Sunday
morning, and then slowly pivoting northeast while continuing=20
through D3 as the surface low moves into Ontario by 00Z/Tuesday.

The synoptic setup is extremely favorable for a classic Midwest
winter storm with widespread intense snowfall. Embedded bands=20
with snowfall rates of 1-3"/hr are expected as reflected by high=20
potential for CSI and even CI in model cross-sections Sunday aftn=20
into Monday which drives intense omega into the TROWAL. Although=20
guidance has continued to trend north, there is high confidence in
a laterally translating band of heavy snow from SD into MN Sunday=20
morning, with the environment transiting into one that matches the=20 conceptual model for a pivoting band over eastern MN and WI Sunday=20
evening into Monday, It is in this area where the heaviest snowfall
is expected, and potentially record, or near-record 2-day snowfall
is possible from eastern MN through WI and northern MI. Elsewhere,
snowfall rates of 1"/hr or more are still likely at times, just=20
with lesser duration. These snowfall rates combined with gusty=20
winds reaching up to 60 mph will create blizzard and near-blizzard
conditions and whiteouts, with major to extreme impacts progged by
the recent WSSI-P. Even in areas that get lower snow totals, the=20
blowing snow potential will still result in difficult travel, and=20
it is likely that most forms of transportation will be treacherous=20
at best, and impossible at worst, through the event across a large=20
area from Montana to Michigan, and everywhere in between.

Event-total snowfall is likely to be extreme in some areas. This is
reflected by 72-hr WPC probabilities (ending 12Z Tuesday) that are
high (>70%) for at least 12" from the Coteau des Prairies of SD
eastward through the Twin Cities, across much of north-central WI,
and the entirety of the U.P. of MI. Where snowfall is most
prolific, likely in northern WI and the U.P of MI, WPC
probabilities indicate a 70-90+% chance of at least 24", and
localized totals of 3-4 feet are possible before this event ends.=20
This could result in record snowfall in some places, and with SLRs
being slightly below climo, combined with the strong winds, power=20
outages and long-lasting impacts are expected. For these reasons,=20
Winter storm key messages are in effect, and are linked below (Key=20
Message 1).

On the S/SE side of this snowfall swath, an axis of mixed=20
precipitation is likely, leading to icing accretion from central IA
through southeast WI and into lower MI. The most significant icing
is expected for lower MI where WPC probabilities for at least=20
0.25" of ice have climbed to over 50%, and the axis of higher
probabilities for at least 0.10" of ice have extended back into SE
WI.

As this system finally departs late D3, pronounced CAA on NW flow
in its wake could result in some lake effect snow in the favored NW
snow belts downstream of all the Great Lakes. WPC probabilities are
moderate (50%) for at least 4" of snow from LES in SW MI, as well
as along the Chautauqua Ridge and into the Tug Hill Plateau.
Additional heavy snow will occur near Marquette, MI as well, adding
onto the extreme snowfall event there the next few days.


...Cascades, Northern & Central Rockies...=20
Day 1...

The persistent atmospheric river (AR) which has plagued the Pacific
and Interior Northwest the past several days will finally come to=20
an end Saturday as the IVT plume weakens and sinks southward into
CA. This will be the result of the intensifying shortwave diving
out of British Columbia and pushing a surface low pressure east,
which will then trail its accompanying cold front southward into
the Great Basin. Much of of the available moisture will be focused
ahead of this front, so as the front digs south, the moisture will
follow, bringing a slow end to this impressive event. Strong
ascent will continue, at least the first half of the period, into
the Northern Rockies, with ascent expanding into the Central
Rockies as well, and this is where the heaviest snowfall is
expected before everything shifts into the middle of the country by
D2. Additional snowfall in the Cascades is expected to be minimal,
but WPC probabilities are high (>70%) for at least 6 additional
inches in the Absarokas, Tetons, and Wind Rivers, with locally more
than 12 inches possible in the higher elevations.


...Northeast...=20
Day 1...

The intense and compact low pressure over the Great Lakes tonight
will eject eastward with secondary cyclogenesis expected along the
coast of Maine Saturday morning. Although this low will become=20
dominant as it pivots into the Canadian Maritimes, an elongated=20
inverted trough extending west from this low will maintain ascent=20
across the Northeast much of Saturday.

Continued impressive WAA/theta-e advection into ME will manifest as
periods of heavy snow across that state, especially just northeast
of the surface low and up along the eastern half of the state.=20
This is where the heaviest snow rates are expected, and may exceed=20
1"/hr as suggested by HREF probabilities surpassing 70% across=20
eastern Maine. Here, WPC probabilities indicate a 50-90% chance of
4+ inches of snow today.
=20
Farther west, NW flow along and behind the residual inverted trough
will leave periods of light to moderate snow across the interior=20
northeast, with local snowfall maxima occurring in favored upslope=20
terrain and across the Tug Hill Plateau where some lake enhancement
off Lake Ontario is expected. Snowfall inland may be less than
along the coast, but WPC probabilities indicate around a 70% chance
of 4+" of snow, highest across the Tug Hill Plateau and Green
Mountains of VT, before the system exits and snow ends by Sunday=20
morning.


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!7M5ro4GT31sY3zKNuesvKLtIgiKZkjMEGn_kmMJwtIprZ= a6Uy7J48cciO8XAeFRYymT66kYFHU9djMdFC8k1wQNJfvE$=20



$$

=3D =3D =3D
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FOUS11 KWBC 141948
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
348 PM EDT Sat Mar 14 2026

Valid 00Z Sun Mar 15 2026 - 00Z Wed Mar 18 2026

...Northern High Plains through the Great Lakes...=20
Days 1-3...

...Blizzard expected this weekend with widespread major impacts=20
and record-breaking snowfall for portions of the Upper Midwest and=20
Great Lakes...

Confidence continues to be high for a widespread major winter=20
storm from the Northern Plains through the Upper Midwest and Great=20
Lakes as a lee surface low lifts northeast and rapidly deepens into
an increasingly moist column. While it is this lee cyclone that=20
will be responsible for the most significant impacts, this event is
really two-pronged with the first event already ongoing across the
Northern High Plains.

The more significant portion of this event has begun this=20
afternoon as lee cyclogenesis begins in more impressive fashion=20
east of CO/WY. A digging shortwave over Idaho, Montana, and=20
Wyoming will drive impressive height falls downstream, with=20
impressive jet streak intensification occurring as a result. The=20
overlap of height falls with this jet development will lead to a=20
rapidly deepening surface low tracking from CO to IA before 12Z=20
Sunday.=20

After 00Z Sunday is when this event truly becomes a major winter
event with widespread considerable impacts. As the surface low
continues east from the Central Plains it will encounter dual=20
moisture streams, one from the decaying AR pushing east, and a=20
second as the theta-e ridge begins to arc northward on intensifying WAA/southerly flow out of the Gulf. The overlap of robust deep=20
layer ascent with maximizing moisture return will deepen the low=20 substantially, and help expand a considerable precipitation shield,
with heavy snow arcing from SD through the Great Lakes by Sunday
morning, and then slowly pivoting northeast while continuing=20
through D3 as the surface low moves into Ontario by 00Z/Tuesday.

The synoptic setup is extremely favorable for a classic Midwest
winter storm with widespread intense snowfall. Embedded bands=20
with snowfall rates of 1-3"/hr are expected as reflected by high=20
potential for CSI and even CI in model cross-sections Sunday aftn=20
into Monday which drives intense omega into the TROWAL. Although=20
guidance has continued to trend north, there is high confidence in
a laterally translating band of heavy snow from SD into MN Sunday=20
morning, with the environment transiting into one that matches the=20 conceptual model for a pivoting band over eastern MN and WI Sunday=20
evening into Monday, It is in this area where the heaviest snowfall
is expected, and potentially record, or near-record 2-day snowfall
is possible from eastern MN through WI and northern MI. Elsewhere,
snowfall rates of 1"/hr or more are still likely at times, just=20
with lesser duration. These snowfall rates combined with gusty=20
winds reaching up to 60 mph will create blizzard and near-blizzard
conditions and whiteouts, with major to extreme impacts progged by
the recent WSSI-P. Even in areas that get lower snow totals, the=20
blowing snow potential will still result in difficult travel, and=20
it is likely that most forms of transportation will be treacherous=20
at best, and impossible at worst, through the event across a large=20
area from Montana to Michigan, and everywhere in between.

Event-total snowfall is likely to be extreme in some areas. This is
reflected by 72-hr WPC probabilities (ending 12Z Tuesday) that are
high (>70%) for at least 12" from the Coteau des Prairies of SD
eastward through the Twin Cities, across much of north-central WI,
and the entirety of the U.P. of MI. Where snowfall is most
prolific, likely in northern WI and the U.P of MI, WPC
probabilities indicate a 70-90+% chance of at least 24", and
localized totals of 3-4 feet are possible before this event ends.=20
This could result in record snowfall in some places, and with SLRs
being slightly below climo, combined with the strong winds, power=20
outages and long-lasting impacts are expected. For these reasons,=20
Winter storm key messages are in effect, and are linked below (Key=20
Message 1).

After 00Z Tuesday, snowfall rates will be waning rapidly in direct
association with the storm, transitioning more and more to lake-
effect snows downwind of all of the lakes. Pronounced CAA on NW=20
flow in its wake could result in some lake effect snow in the=20
favored NW snow belts downstream of all the Great Lakes. WPC=20
probabilities are moderate (50%) for at least 4" of snow from LES=20
in SW MI, as well as along the Chautauqua Ridge and into the Tug=20
Hill Plateau. Additional heavy snow will occur near Marquette, MI=20
as well, adding onto the extreme snowfall event there the next few=20
days. The lake- effect will continue into Tuesday morning before=20
largely dissipating.

On the S/SE side of this snowfall swath, an axis of mixed=20
precipitation is likely, leading to icing accretion from central IA
through southeast WI and into lower MI. The most significant icing
is expected for lower MI where WPC probabilities for at least=20
0.25" of ice have climbed to near 60%, and the axis of higher=20
probabilities for at least 0.10" of ice have extended back into SE=20
MN.

Wegman/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!7bG1910CLlgLJuzDPd_Vczrgw-IRTElc1yUV_8uBMMFVE= vbn7GQcCSQee7usdL_U3DMmDf_kaBI_viSxwjX0jWTvFfk$=20



$$

=3D =3D =3D
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FOUS11 KWBC 150801
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
401 AM EDT Sun Mar 15 2026

Valid 12Z Sun Mar 15 2026 - 12Z Wed Mar 18 2026

...Northern High Plains through the Great Lakes...=20
Days 1-3...

...Blizzard expected this weekend with widespread major impacts=20
and record-breaking snowfall for portions of the Upper Midwest and=20
Great Lakes...

Confidence continues to be high for a widespread major winter=20
storm across the Upper Midwest and Great Lakes as a lee surface=20
low lifts northeast and rapidly deepens into an increasingly moist=20
column. Snowfall from Minnesota through Wisconsin and northern
Michigan, including the U.P, will breach 12" in many locations with
areas of northern WI into the U.P. likely to exceed 24" by the
storms closure.

Current WV satellite and UA analysis indicates a maturing synoptic
evolution with a digging shortwave across WY and an attendant=20
surface low currently analyzed over the western High Plains of=20
Kansas. As the shortwave trough digs further to the southeast, flow
will become increasingly meridional over the Central Plains to=20
Mississippi Valley with the trough axis forecast to tilt neutral
to eventually negative with the 5H height pattern expected to close
off near or over IA by later this evening. Surface low will trek
northeast over the course of Sunday, intensifying slowly as it
migrates towards the southern edge of Lake Michigan by nightfall.
As the upper pattern closes off and takes on the negative trough
orientation, surface low will rapidly intensifying as it begins to
enter into its full maturation phase as the primary heights from
850mb to 500mb become more vertically stacked into Monday morning.
The cyclone will finally reach occlusion phase by Monday afternoon,
but surface low pressure will likely be down into the upper 970s by
this juncture over the western Great Lakes, solidifying its
presence with an all-out blizzard for a large chunk of the Midwest
and Great Lakes region. Moisture convergence occurring during the=20
storms life cycle emanating from the decaying AR pushing east, and
a budding theta-e ridge arcing northward on intensifying=20
WAA/southerly flow out of the Gulf will help provide substantial=20
deep layer moisture poleward, as far north as the western Ontario=20
Province in Canada, a testament to the overall fortitude of this=20 disturbance. The overlap of robust deep layer ascent with=20
maximizing moisture return will deepen the low substantially, and=20
aid in the expansion of a considerable precipitation shield, with=20
heavy snow arcing from SD through the Great Lakes already as of the
pre-dawn hours Sunday. Precip field will slowly pivot northeast=20
while continuing through D2 as the surface low moves into Ontario=20
by 00Z/Tuesday.

Little change in the relevant synoptic details referenced in the=20
last forecast as guidance remains steadfast in all facets of this=20
storms anticipated evolution. The synoptic setup is extremely=20
favorable for a classic Midwest winter storm with widespread=20
intense snowfall. Embedded bands with snowfall rates of 1-3"/hr are
expected as reflected by high potential for CSI and even CI in=20
model cross- sections Sunday aftn into Monday which drives intense=20
omega into the TROWAL. There remains high confidence in a laterally
translating band of heavy snow from SD into MN Sunday morning,=20
with the environment transiting into one that matches the=20
conceptual model for a pivoting band over eastern MN and=20
WI/Michigan U.P. Sunday evening into Monday. It is in this area=20
where the heaviest snowfall is expected, and potentially record, or
near- record 2-day snowfall is possible from eastern MN through WI
and northern MI. Elsewhere, snowfall rates of 1"/hr or more are=20
still likely at times, just with lesser duration. These snowfall=20
rates combined with gusty winds reaching up to 60 mph will create=20
blizzard and near-blizzard conditions and whiteouts, with major to=20
extreme impacts progged by the recent WSSI-P. Even in areas that=20
get lower snow totals, the blowing snow potential will still result
in difficult travel, and it is likely that most forms of=20
transportation will be treacherous at best, and impossible at=20
worst, through the event across a large area from Montana to=20
Michigan, and everywhere in between.

Event-total snowfall is likely to be extreme in some areas. This is
reflected by 72-hr WPC probabilities (ending 12Z Tuesday) that are
high (>70%) for at least 12" from southeast MN to points northeast
through north- central WI, and the entirety of the U.P. of MI.=20
Where snowfall is most prolific, likely in northeastern WI and the
U.P of MI, WPC probabilities indicate a 70-90+% chance of at least
24", and localized totals of 3-4 feet are possible before this=20
event ends with the maxima positioned across the Huron Mountains=20
downwind of Lake Superior. This could result in record snowfall in=20
some places, and with SLRs being near to slightly below climo,=20
combined with the strong winds, power outages and long- lasting=20
impacts are expected. For these reasons, Winter storm key messages=20
are in effect, and are linked below (Key Message 1).

After 00Z Tuesday, snowfall rates will be waning rapidly in direct
association with the storm, transitioning more and more to lake-
effect snows downwind of all of the lakes. Pronounced CAA on NW=20
flow in its wake could result in some lake effect snow in the=20
favored NW snow belts downstream of all the Great Lakes. WPC=20
probabilities are moderate (50%) for at least 4" of snow from LES=20
in SW MI, as well as along the Chautauqua Ridge and into the Tug=20
Hill Plateau. Additional heavy snow will occur near Marquette, MI=20
as well, adding onto the extreme snowfall event there the next few=20
days bring storm and LES combination totals towards the 4-5ft range
by Tuesday afternoon. The lake- effect will continue into Tuesday=20
morning before largely dissipating.

On the S/SE side of this snowfall swath, an axis of mixed=20
precipitation is likely, leading to icing accretion from central IA
through southern WI and into the northern mit in lower MI. The=20
most significant icing is expected for the northern mit of MI=20
where WPC probabilities for at least 0.25" of ice have settled=20
between 40-70%, and the axis of higher probabilities for at least=20
0.10" of ice have extended back into southern WI.


...Central Appalachians...

Powerful cyclone over the Great Lakes will provide a strong cold
front trailing the primary surface low as it migrates eastward
through much of the country east of the Mississippi. Once the cold
front advances beyond the Appalachian front, strong cold air
advection (CAA) regime will transpire with rain changing to snow
for the mountains of western PA down through western MD and the
adjacent WV Highlands. Elevations >2000ft will see some snowfall
with the greatest accums focused over areas >2500ft, a general
climo output for this type of evolution. WPC probabilities for >4"
of snowfall are between 20-40% for the entire Appalachian chain of
western PA down through WV. Maxima of 40-60% is located over the
Canaan Valley down into Snowshoe, WV where some deterministic
output are printing out upwards of 6-8" of high ratio snowfall
post-fropa. Setup and magnitude of the upslope flow is classic for
this scenario allowing for growing confidence in at least minor
impacts for the terrain of the Mid Atlantic.=20

Weiss/Kleebauer



...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!5Mz4bRZVZZ9RVDTb1sBqsu4WHXcb-lCcyrgMk_jU8_b5T= PaB831GnEHgCTyaR_6m85bP8GQekWHF3E-8MTlD2oSyFkY$=20



$$

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FOUS11 KWBC 151805
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
205 PM EDT Sun Mar 15 2026

Valid 00Z Mon Mar 16 2026 - 00Z Thu Mar 19 2026

...Upper Mississippi Valley through the Great Lakes...=20
Days 1-3...

...Historic blizzard ongoing through Monday with widespread major=20
impacts and record-breaking snowfall for portions of the Upper=20
Midwest and Great Lakes...

Confidence continues to be high for a widespread major winter=20
storm across the Upper Midwest and Great Lakes as a lee surface=20
low lifts northeast and rapidly deepens into an increasingly moist=20
column. Snowfall from Minnesota through Wisconsin and northern
Michigan, including the U.P, will breach 12" in many locations with
areas of northern WI into the U.P. likely to reach 2-4 feet of
accumulation through Monday night.

A rapidly developing surface low, currently centered near the Quad
Cities of Iowa/Illinois, is being supported both by a digging=20
upper level trough to its west over Nebraska and Kansas and the=20
RER of a 160 kt jet streak to its north and east. A couple of lines
of showers and storms are moving across Iowa and eastern Illinois,
supported by a southwesterly low level jet, pumping in Gulf=20
moisture and locally increasing both shear and unstable, warm air,
feeding the storms. As the shortwave trough digs further to the=20
southeast, flow will become increasingly meridional over the=20
Central Plains to Mississippi Valley with the trough axis forecast=20
to tilt neutral to eventually negative with the 500 mb height=20
pattern expected to close off near or over IA by later this=20
evening. Meanwhile, a maturing "comma-head" has emerged that is
largely snow from Nebraska through the U.P. and into Ontario. There
have already been reports of snow rates of 4 inches per hour, as
several locations have eclipsed the 20 inch mark for accumulations
into Minnesota and Wisconsin.=20


The surface low center will track east into this evening,=20
intensifying as it then turns northeast towards the Straits of
Mackinac by Monday afternoon. As the upper pattern takes on the=20
negative trough orientation, the surface low will rapidly=20
intensify as it begins to enter into its full maturation phase.=20
The primary heights from 850mb to 500mb become more vertically=20
stacked into Monday morning. The cyclone will finally reach=20
occlusion phase by Monday afternoon, but surface low pressure will=20
likely be down into the upper 970s by this juncture over the=20
western Great Lakes, solidifying its presence with an all-out=20
blizzard for a large chunk of the Midwest and Great Lakes region.=20
A classic comma-shaped storm will develop, with cold conveyor belt
supplying ample Gulf moisture into some unusually cold air for this
time of year on the north side of the storm. Thus, expect multiple
bands of heavy snow to develop, which will likely remain nearly
stationary as they pivot around the northeastward-tracking surface
low. Where these stationary bands remain in place the longest is
where the highest snow totals with this storm will be realized.

There has been little change in the relevant synoptic details=20
referenced in the last forecast as guidance remains steadfast in=20
all facets of this storms anticipated evolution. The synoptic setup
is extremely favorable for a classic Midwest winter storm with=20
widespread intense snowfall. Embedded bands with snowfall rates of=20
1-3"/hr are expected as reflected by high potential for CSI and=20
even CI in model cross- sections Sunday aftn into Monday which=20
drives intense omega into the TROWAL. There remains high confidence
in a pivoting band over eastern MN and WI/Michigan U.P. this=20
evening into Monday. It is in this area where the heaviest snowfall
is expected, and potentially record, or near- record 2-day=20
snowfall is possible from eastern MN through WI and northern MI.=20

Elsewhere, snowfall rates of 1"/hr or more are still likely at=20
times, just with lesser duration. These snowfall rates combined=20
with gusty winds reaching up to 60 mph will create blizzard and=20 near-blizzard conditions and whiteouts, with major to extreme=20
impacts progged by the recent WSSI-P. Even in areas that get lower=20
snow totals, the blowing snow potential will still result in=20
difficult travel, and it is likely that most forms of=20
transportation will be treacherous at best, and impossible at=20
worst, through the event across a large area from Montana to=20
Michigan, and everywhere in between.

Event-total snowfall is likely to be extreme in some areas. This is
reflected by 72-hr WPC probabilities (ending 00Z Wednesday) that=20
are high (>70%) for at least 12" from southeast MN to points=20
northeast through north- central WI, and the entirety of the U.P.=20
of MI. Where snowfall is most prolific, likely in northeastern WI=20
and the U.P of MI, WPC probabilities indicate a 70-90+% chance of=20
at least 24", and localized totals of 3-4 feet are possible before=20
this event ends with the maxima positioned across the Huron=20
Mountains downwind of Lake Superior. This could result in record=20
snowfall in some places, and with SLRs being near to slightly below
climo, combined with the strong winds, power outages and long-=20
lasting impacts are expected. For these reasons, Winter storm key=20
messages are in effect, and are linked below (Key Message 1).

After 00Z Tuesday, snowfall rates will be waning rapidly in direct
association with the storm, transitioning more and more to lake-
effect snows downwind of all of the lakes. Pronounced CAA on NW=20
flow in its wake could result in some lake effect snow in the=20
favored NW snow belts downstream of all the Great Lakes. WPC=20
probabilities are moderate (50%) for at least 4" of snow from LES=20
in SW MI, as well as along the Chautauqua Ridge and into the Tug=20
Hill Plateau. Additional heavy snow will occur near Marquette, MI=20
as well, adding onto the extreme snowfall event there the next few=20
days bring storm and LES combination totals towards the 4-5ft range
by Tuesday afternoon. The lake- effect will continue into Tuesday=20
morning before largely dissipating.

On the S/SE side of this snowfall swath, an axis of mixed=20
precipitation is likely, leading to icing accretion from central IA
through southern WI and into the northern mit in lower MI. The=20
most significant icing is expected for the northern mitt of MI=20
where WPC probabilities for at least 0.25" of ice have settled=20
between 40-70%, and the axis of higher probabilities for at least=20
0.10" of ice have extended back into southern WI.

...Post-storm lake-effect...

Behind the storm, a very cold air mass, characterized by 850 mb
temperatures within a couple degrees on either side of -20C, will
plunge across all of the Great Lakes for the Days 2 and 3 periods
from Monday night through Tuesday night. Widespread multi-bands are
expected along the long axis of all of the upper Great Lakes, while
the lake-effect will eventually congeal into single bands downwind
of the lower lakes, especially Ontario. Fortunately, as far as
lake-effect snowstorms go, this will be relatively short-lived,
with the lake-effect ending on the upper lakes by late in the day
Tuesday and on the lower lakes by Wednesday morning as 850 mb
temperatures warm sufficiently to end the lake-effect. WPC
probabilities for 4 inches of snow are high (>70%) for the
southwest corner of Michigan, the Chautauqua Ridge of far western
New York, and east of Lake Ontario. The Tug Hill region
probabiliites are over 90% for 4 inches of snow.=20


...Central Appalachians...
Day 2...


A powerful cyclone over the Great Lakes will send a strong cold=20
front eastward through much of the country east of the=20
Mississippi. Once the cold front advances beyond the spine of the=20 Appalachians, a strong cold air advection (CAA) regime will=20
transpire with rain changing to snow for the mountains of western=20
PA down through western MD and the adjacent WV Highlands.=20
Elevations >2000ft will see some snowfall with the greatest accums=20
focused over areas >2500ft, a general climo output for this type of
evolution. WPC probabilities for >4" of snowfall are between=20
moderate to high (60-80%) from far western Maryland through WV. The
setup and magnitude of the upslope flow is classic for this=20
scenario allowing for growing confidence in at least minor impacts=20
for the terrain of the Mid Atlantic.=20

Wegman


...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!45USA_IH1VuxZq-iR1wGBLb2UqxgKNGXwDaXY8HsLLdoc= ugqTPlMIEddpP2rq7Lan9MbfZYOMPfUTxvjUyNQxrWTiH0$=20



$$

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FOUS11 KWBC 160704
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
304 AM EDT Mon Mar 16 2026

Valid 12Z Mon Mar 16 2026 - 12Z Thu Mar 19 2026

...Upper Midwest through the Great Lakes...=20
Days 1-3...

...Historic blizzard continues today...

The historic blizzard which has been plaguing the Northern Plains
and Upper Midwest will continue in earnest today across the Great
Lakes. The strong surface low driving this impressive event will
steadily advect northeast today after a brief stall this morning
over Michigan during occlusion, leading to continued heavy snow
from northern IL through the U.P. of MI. The low is expected to
pull away well into Canada by 12Z/Tuesday, bringing a slow end to
the blizzard.

The heaviest additional snowfall is expected from southern WI
through the U.P. of MI where snowfall rates above 1"/hr may (60-80%
chance) continue through evening, with the heaviest snowfall
expected in the higher terrain of the U.P. near the Huron
Mountains. The most widespread heavy synoptic snow will wane after
00Z/Tuesday, but before this occurs, the combination of these=20
intense snowfall rates and gusty winds of up to 50 mph will
continue blizzard conditions. The heaviest snowfall swath D1 is=20
likely within the impressive deformation axis which will be
pivoting west of the surface low as it lifts north, and this
deformation is progged to dig as far south as IL/IA Monday morning.
This will bring periods of heavy snow and gusty winds with near-
blizzard conditions even south of the heaviest snow. However,
WPC probabilities indicate the heaviest snow is likely for northern
WI, including the Door Peninsula, into the U.P. of MI where they
reach 50-90% for an additional 6+ inches of snow today, with
locally more than 12 inches possible across the U.P. thanks to lake
effect snow contribution (more on that below).

The ongoing key messages for this historic blizzard remain, and are
linked below (Key Message 1).

As the low pulls away late D1 into D2, the heavy synoptic snow will
draw to an end, but impressive NW winds and CAA in its wake will
bring a period of widespread lake effect snow (LES) to the Great=20
Lakes. Although the lake temperatures are cold, below +5C, and=20
there is considerable ice cover according to GLERL, 850mb temps=20
crashing to around -20C will create steep lapse rates and=20
impressive inversion heights with pronounced omega into the near-=20
surface DGZ. This should be more than sufficient to support heavy=20
LES, with rates above 1"/hr (30-60% chance). While the duration of
heavy LES may be somewhat limited as winds begin to weaken and veer
as the low pulls away, there is sufficient time for locally heavy
accumulations in the favored NW snow belts. WPC probabilities for
LES are high D1 (>70%) for 4+ inches in the NW L.P. of MI near
Traverse City, the far SW portions of the L.P. of MI, and greater
than 50% along the Chautauqua Ridge and the Tug Hill Plateau. LES
wanes in coverage D2 but persists heavily east of Lake Ontario
where probabilities remain elevated (50-90%) for an additional 4+
inches through Tuesday night.


...Central Appalachians & Mid-Atlantic states...
Days 1-2...

The strong low pressure /blizzard/ over the Great Lakes will
steadily move northeast into Canada today, while the parent upper
trough amplifies into the Tennessee Valley and takes on a negative
tilt. This will push a powerful arctic cold front eastward across
the Ohio Valley, Central Appalachians, and Mid-Atlantic states
today. As this front races east, temperatures will plummet on
strong CAA, while mid and upper level flow remains southerly in
response to the strongly tilted and digging upper trough. This will
likely result in precipitation changing over to snow before ending
in most areas.=20

While most of this snow will just be conversational, in the colder
climates of the higher elevations of the Central Appalachians, this
may result in a two-pronged event consisting of heavy snow. The
first will be directly behind the front as p-type changes rapidly
from rain to snow, leading to a brief period of snowfall rates
exceeding 1"/hr (40-60% chance) from the Central Appalachians=20
through the Laurel Highlands and into the Finger Lakes region of=20
NY. During this time, however, snowfall accumulations will be=20
modest at just a few inches at most. However, in the wake of this=20
front, the increasing CAA on NW flow will drive potent upslope=20
ascent into the Central Appalachians Monday night through Tuesday=20
aftn. Although the column is dry aloft, the DGZ will lower to near=20
the surface, leading to favorable ascent due to the upslope to=20
maximize snow growth. This should cause accumulating snowfall in=20
the higher elevations of WV, where WPC probabilities peak above 50%
for 6+ inches of snowfall.

Finally, as the trailing vorticity maxima and secondary shortwave
embedded within the trough finally kicks east Tuesday aftn/eve,
convective snow showers and isolated snow squalls could develop=20
across this area. Additional snowfall accumulations will be light=20
with any of these convective elements, but briefly heavy snow rates
and gusty winds could cause local travel impacts.


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!-YEUl4DZ-_f4nBc_zlclvHZTEy2Prhp8OA7kp4NGWeHQ-= gEPJE_lo4KVd8ZWt9WZjMW1K3N4Q5A2j5ulJY71QtZO72E$=20



$$

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FOUS11 KWBC 161822
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
222 PM EDT Mon Mar 16 2026

Valid 00Z Tue Mar 17 2026 - 00Z Fri Mar 20 2026

...Great Lakes...
Days 1-2...

...Blizzard conditions to persist through this evening in the
Northern Great Lakes...

As this historic winter storm races north and east into eastern=20
Canada tonight, potent NW winds and CAA in its wake will produce=20
widespread lake effect snow (LES) over the Great Lakes. Although=20
lake temperatures are cold and somewhat ice covered, according to=20
GLERL, 850mb temps crashing to as low as -20C will foster steep=20
lapse rates and sufficiently saturated profiles within the DGZ=20
aloft. The result will be LES snow bands with rates above 1"/hr=20
(40-70% chance) tonight and into Tuesday morning. Winds should=20
begin to lessen on Tuesday as high pressure builds in from the=20
west, but prolonged cyclonic flow will fuel rounds of moderate-to-=20
heavy snow in the favored snow belts east of Lakes Erie and
Ontario. LES bands should finally taper off by Tuesday night.

WPC probabilities for LES are moderate-to-high D1 (50-70) for 4+=20
inches in the northwest portion of Michigan's Mitten near Traverse=20
City, along the eastern U.P., and in the southwest L.P.. Farther=20
east, probabilities around 50% for snowfall >4" are located along=20
the Chautauqua Ridge and the Tug Hill Plateau. The Tug Hill on
south closer to Oswego, NY could see locally heavy totals with
low-to-moderate chances (30-50%) for snowfall totals over 12=20
inches possible.=20


...Central Appalachians & Interior Northeast...
Days 1-2...

A powerful arctic front will race through the Northeast and Mid-
Atlantic by this evening. In wake of this FROPA, temperatures will
plummet due to strong CAA, while mid and upper level flow remains=20
southerly in response to the strongly tilted and digging upper=20
trough. Combined with upslope enhancement, this will cause=20
precipitation to rapidly transition to snow from the Central=20
Appalachians and Laurel Highlands to the Finger Lakes of NY and the Catskills/Adirondacks.

While most of this snow will just be conversational at lower
elevations, in the higher elevations of the Central Appalachians,=20
a two-part event supporting of heavy snow is anticipated. The=20
first will be directly behind the front as p-type changes rapidly=20
from rain to snow, leading to a brief period of snowfall rates=20
surpassing 1"/hr (40-60% chance) from the Central Appalachians=20
through the Laurel Highlands and into the Finger Lakes region of=20
NY. This first round of snowfall accumulations will be modest,
generally in the 1-3" initially. However, behind the front, the=20
increasing CAA via NW flow will foster healthy upslope ascent into
the Central Appalachians tonight through Tuesday. Typically favored
areas along the Potomac Highlands and Alleghenies above 2,000ft
will be favored for long snow durations, and thus higher totals.=20
WPC probabilities peak above 50% for 6+ inches of snowfall.

In addition, as the trailing vorticity maxima and secondary=20
shortwave embedded within the trough over the OH Valley moves east
Tuesday afternoon, convective snow showers and isolated snow=20
squalls could develop across this area. Areas from the southern
tier of NY, western and central PA, and on south to the Central
Appalachians would be the most likely areas to contend with any
potential snow squalls. Additional snowfall accumulations will be=20
light with any of these convective elements, but briefly heavy snow
rates and gusty winds could cause local travel impacts due to rapid
reductions in visibility.


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!_PBmGNDDtPkqf99AfBb9zAW0sYahBWciDI3fczJK8meXB= oxjP-bprusGbhxlHvC5KcNZELrZF-Wv5J8glSkQJf207U4$=20



$$

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FOUS11 KWBC 170624
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
224 AM EDT Tue Mar 17 2026

Valid 12Z Tue Mar 17 2026 - 12Z Fri Mar 20 2026

...Great Lakes southeast through the Mid-Atlantic...
Day 1...

Strong low pressure which produced the blizzard over the Upper
Midwest/Western Great Lakes will be well northeast into Canada this
morning, while its trailing arctic cold front will be positioned
just off the Atlantic Seaboard to start the period. Behind this low
and the associated front, strong CAA on NW winds will be widespread
across the Great Lakes, Central Appalachians, and Mid-Atlantic
States, while a lagging but potent upper trough swings through the
Ohio Valley. The overlap of this upper trough and the post-frontal
NW flow will result in 3 areas of moderate to heavy snowfall today.

1) Great Lakes: CAA on the NW cyclonic flow will drop 850mb temps
to as low as -20C (or slightly colder). This cold air moving across
the lakes will lead to very steep lapse rates and rising inversion
depths despite lake surface temperatures that are generally +5C or
less according to GLERL. This will support efficient lake effect
snow (LES) in the favored W/NW snow belts, and although the
duration of any single bands may be modest due to the movement of
the mid- level trough, heavy snow rates in excess of 1"/hr are
possible (30-50%) within any LES bands. The heaviest accumulations
are likely across the Tug Hill Plateau and then down towards
Syracuse, where WPC probabilities are high (>70%) for at least 4
inches of snow, with locally more than 8 inches possible.

2) Central Appalachians: The persistent NW flow will generally
result in a drying column across the area. However, as the mid-
level trough swings overhead, it will briefly provide some
additional synoptic ascent through height falls/PVA, overlapping
favorable upslope flow into the terrain to produce periods of
moderate to heavy snow. The nature of this snow may be more snow
"showery" that continuous, limiting accumulations overall. However,
snowfall rates may at times reach 1"/hr (10-30% chance) leading to
locally as much as 4 inches of snow (10-30% chance) in the higher
terrain of WV and into the Laurel Highlands of PA.

3) Ohio Valley to the Mid-Atlantic: As the mid-level trough swings
overhead this aftn/eve, it will likely encourage some bubbling of
convective snow showers and isolated snow squalls across the
region. Lapse rates become impressively steep beneath this trough,
and there will be just enough moisture to generate numerous
convective snow showers which will move rapidly east through the
evening. The SnSq parameter is high for OH/WV/PA, and lesser due to
drier air farther east. While snow squalls can't be ruled out,
this is more likely to manifest as scattered to numerous convective snow showers across the area. Accumulation from these will be minimal,
but brief heavy snow rates and gusty winds could cause rapid
changes in visibility and hazardous driving later today.


The probability for significant icing across the country is less
than 10%.


Weiss


$$

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FOUS11 KWBC 171830
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
230 PM EDT Tue Mar 17 2026

Valid 00Z Wed Mar 18 2026 - 00Z Sat Mar 21 2026

...Upper Midwest to the Northeast...

The CONUS continues to enter a notably more tranquil pattern
regarding heavy snow following the departure of the historic mid-
March blizzard. Widespread heavy snow (accumulations greater than 4
inches) is not expected across the lower 48 through late Friday.

However, the upper level pattern is forecast to remain amplified,
with a strong ridge anchored over the western U.S., while a broad
trough remains centered over the East. An amplified shortwave
currently moving through the base of this eastern trough will lift
out today, but the overall pattern will persist through the end of
the week.

Tonight into Wednesday, a low-amplitude shortwave sliding through
the northern northern tier will trigger a round of warm advection precipitation. Expect a swath of light snow, with some freezing
rain in spots, to develop from the upper Mississippi Valley to the
western Great Lakes. WPC probabilities indicate minor impacts for
most areas, with snow totals capped at 1-2 inches.

Further downstream, lake effect snows will persist in the lee of
Lake Ontario, with several more inches possible along a narrow
band southeast of the lake before winds back to the south tomorrow.

A more amplified shortwave is forecast to dive into the northern
Great Lakes on Friday. However, accumulations are expected to
light and largely confined to northern Michigan.

The probability for significant icing across the country is less
than 10%.

Pereira

$$

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FOUS11 KWBC 180619
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
219 AM EDT Wed Mar 18 2026

Valid 12Z Wed Mar 18 2026 - 12Z Sat Mar 21 2026

...Upper Midwest to the Northeast...
Days 1-2...

Generally quiet winter weather encompasses the CONUS the next
several days as flat and fast flow keep systems progressive and
weak. Within this regime, multiple weak shortwaves traversing WNW
to ESE from the Northern Plains into the Mid-Atlantic and New
England will bring brief periods of light snow and mixed
sleet/freezing rain. In general, this will produce only minor
impacts and no significant snowfall. However, even light freezing
rain can be problematic to travel, so although WPC probabilities
for even 0.1" of ice are less than 5%, some light freezing rain
above 0.01" is likely (>70%) D1 for Wisconsin and lower Michigan,
and again D2 for far southern Michigan into Indiana/Ohio, which
could create travel difficulties due to icy roads.

Weiss


$$

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FOUS11 KWBC 181910
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
310 PM EDT Wed Mar 18 2026

Valid 00Z Thu Mar 19 2026 - 00Z Sun Mar 22 2026

...Upper Midwest to the Northeast...
Days 1-3...

A quiet pattern with respect to heavy snow and icing will continue,
with widespread heavy snow or significant icing not expected across
the contiguous U.S. through the end of the week.

Precipitation associated with a low-amplitude shortwave sliding
southeast across the Upper Midwest is expected to produce some
minor ice accumulations tonight from northern Wisconsin southeast
into southern Michigan and far northern Indiana.

Meanwhile, a more amplified shortwave to the north will spread
light snow from far northern Michigan to Upstate NY and northern
New England as it swings across southeastern Canada on Thursday.

A second shortwave will amplify over the northern Great Lakes on
Friday and move east across the Northeast on Saturday, bringing
additional light snow accumulations to the same regions. Apart
from some localized heavier amounts in the higher reaches of the
Adirondacks and the northern New England mountains, three-day snow accumulations are expected to top out at only an inch or two for
most of the impacted locations.

Pereira

$$

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FOUS11 KWBC 190611
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
211 AM EDT Thu Mar 19 2026

Valid 12Z Thu Mar 19 2026 - 12Z Sun Mar 22 2026

...Upper Great Lakes to the Northeast...
Days 1-3...

Thanks to a dome of upper-level ridging firmly entrenched over
the West and northerly low-level winds over the Mid-South all but
cutting off Gulf moisture, a quiet pattern with respect to heavy
snow and icing will continue. The lone cases where light snow
accumulations are anticipated are across the Upper Great Lakes and
Northeast as Canadian clipper systems race across the southern
tier of the country and occasional pass through. A clipper over
Ontario will direct a warm front through the Northeast with minor
snowfall totals (generally a coating-2", with local 2-3" in the
Adirondacks and White Mountains) through Thursday. As that system
exits over Atlantic Canada, a more organized clipper will be
tracking towards Lake Superior. Light snow will ensue along the
warm front over the U.P. of MI, Thursday night and into Friday AM,
then race over northern NY and northern New England Friday
afternoon and evening.

There are some hints in AI guidance (EC-AIFS most notably) that the
clipper could strengthen by the time it reaches Downeast Maine
early Saturday morning. This could lead to locally heavier snowfall
in the Greens, Whites, and northern ME on Saturday. At the moment,
WPC probabilities shows low chances (10-30%) chances for snowfall

4" in northern ME with most snowfall generally under 3". But this

will be closely monitored given the generally good performance of
the EC-AIFS for much of the cold season.


The chances for significant icing across the CONUS is less than 10
percent.


Mullinax




$$

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FOUS11 KWBC 191903
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
303 PM EDT Thu Mar 19 2026

Valid 00Z Fri Mar 20 2026 - 00Z Mon Mar 23 2026

...Upper Great Lakes to the Northeast...
Days 1-3...

Ridge/trough upper pattern over the CONUS will continue to bring
northern stream systems through the Great Lakes into the Northeast
with minor to occasionally modest snowfall. A system over southern
Canada this evening will push through the Great Lakes tonight and
into southern/southeastern Ontario tomorrow. WAA-driven snow and
some light icing is likely over the U.P. of Michigan and into
northern Lower Michigan. As the clipper moves into the Northeast
tomorrow afternoon/evening, snow will fall mostly over the higher
elevations (above 1500ft or so) where WPC probabilities for at
least 4" are >50%, with lesser accumulations to the valley floors
(T-2"). Precipitation should end on Saturday morning.

The next system will slip into northern MN and the western Great
Lakes Saturday afternoon/evening. With a southwest-to-northeast
thermal gradient, some icing is possible once again over
northeastern MN, northern WI, and northern Lower Michigan near the
surface warm front. That system may track a bit farther south,
which could bring in at least some light to modest snow to
northeastern MN into the U.P. of Michigan. There, WPC probabilities
for at least 4 inches of snow are >40% Saturday into very early
Sunday. The system will race eastward and bring another swath of
snow to northern NYS into New England Sunday. Through 00Z/Mon, WPC probabilities for an additional 4 inches of snow are >30% over the
higher elevations of the northern Adirondacks into the Green/White
Mountains, but the snow will continue beyond this forecast range.


The chances for significant icing across the CONUS is less than 10
percent.

Fracasso

$$

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FOUS11 KWBC 200701
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
301 AM EDT Fri Mar 20 2026

Valid 12Z Fri Mar 20 2026 - 12Z Mon Mar 23 2026

...Upper Great Lakes to the Northeast...
Days 1-3...

The first in a series of clipper systems will produce periods of
snow across northern New York and northern New England today. Low-
level WAA ahead of the clipper will support periods of snow, even
down to the valley floors in northern New England. However,
snowfall rates and elevation will play critical roles in snowfall accumulations. Most notably, the Adirondacks, Green, and White
Mountains are most favored for >1"/hr snowfall rates. WPC
probabilities depict localized moderate probabilities (40-60%) for
snowfall totals >4" with the peaks of these mountain ranges
(including Mt. Washington) sporting low chances (10-30%) for
snowfall accumulations as high as 6". Otherwise, most elevations
below 1,000ft are likely to see anywhere from a coating to as much
as 3". The WSSI does depict some Minor Impact potential,
particularly in the Adirondacks and bordering the St. Lawrence
River in NY's North Country. Snow will taper off across northern
New England by Friday night.

As this clipper exits to the east Saturday morning, the next
clipper system is already making its way towards the Upper Great
Lakes. There remains a decent amount of model spread in the
amplitude and progression of this clipper, largely because it is
essentially an unorganized cluster of sheared 500mb vort maxima
tracking over the northern Great Lakes and Northeast. There will be
sufficient upper-level ascent thanks to the left-exit region of a
500mb jet streak will accompany the clipper. There is also
agreement on model guidance on healthy 850-700mb WAA via WSWrly
flow that collides with sufficiently cold boundary layer
temperatures over northern NY and the rest of northern New
England. However, guidance is not yet in agreement on where the
strongest 850-700mb FGEN takes shape, and as a result, disagree on
the placement of the QPF axis to the north of the storm track. WPC
Day 3 cluster analysis shows the departing trough over Nova Scotia
and the depth of the primary 500mb shortwave trough over the Upper
Midwest are the most sensitive factors in determining what this
clipper ultimately produces, and because of the notably shorter
wavelengths, confidence in where the heaviest snowfall will occur
is not clear out to Day 3.

So what we do know-- It is late March and elevation matters a ton.
However you slice it across deterministic guidance or
probabilistic guidance, the Adirondacks, Green, Whites, and
Berkshires are most favored for accumulating snowfall. Even as far
west as the MI U.P. and MN Arrowhead, snowfall totals approaching
4" are possible. WPC probabilities show low-to-moderate chances
(30-50%) for snowfall totals >4" in the Hurons of the MI U.P.
between Saturday night and through Sunday. Farther east, the

2,000ft elevations in the Adirondacks, Greens, and Whites sport

moderate chances (40-60%) for snowfall totals >8" on Sunday. Below
1,000ft, probabilities for snowfall amounts >4" are low (10-30%)
with most accumulations less than 4" expected at this time. WPC's
WSSI-P depicts moderate chances (40-60%) for Minor Impacts in the
MN Arrowhead to much of northern MI due to a combination of snow
and ice (WPC probabilities show low-to-moderate chances, or 30-50%,
for ice accumulations of at least one-hundreth of an inch) late
Saturday into early Sunday. Minor probabilities are highest in
northern New England where moderate probabilities (40-60%) are
present throughout the northern Appalachians. In fact, some
localized 40-50% probabilities for Moderate Impacts are shown
across south-central and Downeast Maine.


The chances for significant icing across the CONUS is less than 10
percent.


Mullinax




$$

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FOUS11 KWBC 202018
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
418 PM EDT Fri Mar 20 2026

Valid 00Z Sat Mar 21 2026 - 00Z Tue Mar 24 2026

...Northeast...
Days 1-3...

A clipper will move into the Northeast Saturday night bringing a
swath of accumulating snowfall to Upstate NY into Northern New
England. Still some uncertainty with the exact track of this
system, which will impact where the heaviest swath of QPF is and
where the rain/snow line sets up. The higher elevations are most
favored for higher snowfall totals, but strong WAA should support a
period of moderate to locally heavy precipitation. This should
allow snow even down to the lower elevations of northern New
England, especially Saturday night into early Sunday. Snow ratios
from the NBM are likely too high with this system. While snow
should be coming down at a decent clip for a stretch, the strongest
lift appears to be mainly centered below the DGZ, which should cap
snowfall ratios. Then during the daylight hours the late March sun
will play a role in lowering ratios further. In fact, where snow
is falling at a lighter clip we probably won't see much
accumulation during the daytime, with accumulations focused in
either the highest terrain or where snow is falling at a heavy
enough clip to overcome the marginal temperatures and higher sun
angle.

The latest WPC snowfall probabilities have increased for the
Saturday night to Sunday timeframe. The probability of exceeding 4"
in the 24hr period ending 00z Monday are generally 40-80% from
Upstate NY into central to northern VT/NH and western ME. The
highest probabilities are in the higher terrain, but values of
30-50% even get into the lower elevation areas. The probabilities
of 6" are 30-60%, with 8" exceedance probabilities as high as
30-50% in the White Mountains of NH. These probabilities seem
reasonable, with exact snowfall totals dependent on the specific track
of the system. This is a scenario where the higher terrain has the
highest probabilities (and thus confidence) in seeing greater
snowfall totals, but there is still a lower risk of impactful snow
getting into some of the lower elevations if a snowfall band is
able to move into these areas overnight or early morning and is
heavy enough to overcome the marginal temperatures.

A bit more uncertainty exists on Monday as a coastal low tries to
develop offshore New England. By this time it will be cold enough
over northern New England for snow, but if precipitation intensity
is light then the high sun angle will likely limit accumulation.
However, a broader and/or more intense snow shield would be
capable of producing additional accumulating snowfall. Models have
been fluctuating regarding this low and inland precipitation
extent...although most 12z models shifted lighter with QPF. Even
the AIFS, which has been more consistently on the wetter side of
the QPF spectrum, did back off at 12z. There is still time for this
to change, but the probabilities of impactful snowfall Monday
appear to be decreasing, but still need to continue to monitor.

The chances for significant icing across the CONUS is less than 10
percent.


Chenard


$$

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FOUS11 KWBC 210715
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
315 AM EDT Sat Mar 21 2026

Valid 12Z Sat Mar 21 2026 - 12Z Tue Mar 24 2026

...Northeast...
Days 1-2...

A clipper system will move southeast out of central Canada and into
the Northeast this weekend. Snow on the leading edge of the
precipitation shield will move into upstate New York this evening,
then spread across New England tonight. The snow will be
characterized by warm advection. With a high sun angle and
plentiful warm air over much of the eastern half of the country,
the warm air will move into New York and southern New England,
resulting in a changeover to rain on Sunday over much of upstate
New York and into southern New England. Meanwhile, over most of
northern New England, the predominant precipitation type remains as
snow as the back edge of the precipitation quickly pushes east
across New England.

The southwesterly flow of warm air will be uplifted by the terrain
of the Adirondacks, Green, and White Mountains. Here, the
combination of upslope and cooler temperatures at higher
elevations will support multiple inches of snow. The heaviest snow
will fall between early Sunday morning and Sunday evening. In the
valleys, warmer temperatures, high sun angle, and snow mostly
falling during the day should all work to keep snow totals much
lower than the adjacent mountains, though still reaching into
advisory criteria. Where snow rates remain lighter, accumulations
during the day should be greatly tempered, and largely confined to
grassy areas.

WPC snowfall probabilities for the storm total snow over 4 inches
are high (over 70%) from the northern Adirondacks east across the
northern Greens of Vermont, northern Whites of New Hampshire, and
much of southern Maine. For much of northern New Hampshire and
western Maine, those probabilities are above 90% for 4 inches and
over 70% for 8 inches. As typical with compact storms, the exact
longevity and intensity of any internal heavy snow bands will
dictate where the highest snowfall totals are observed.

By D3/Monday, a secondary coastal low is expected to form south of
Long Island. The precipitation shield will be narrow and focus
across southern New England, where temperatures will be warm enough
for mostly (or entirely) rain. Thus, the chances for impactful
snow on Monday anywhere in the Northeast continue to decrease.

The chances for significant icing across the CONUS is less than 10
percent.


Wegman



$$

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FOUS11 KWBC 211915
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
315 PM EDT Sat Mar 21 2026

Valid 00Z Sun Mar 22 2026 - 00Z Wed Mar 25 2026

...Northeast...
Days 1-2...

A clipper system will track across the Northeast late today through
Sunday with snow spreading into northern New York this evening and
northern New England overnight. While warm advection will be a
principle driver for the developing precipitation, it combined with
the high angle will support a changeover to rain across much of
Upstate New York and southern New England on Sunday. In contrast,
the higher elevations of the Adirondacks and much of northern New
England are expected to remain cold enough for snow to remain the
primary precipitation type before the system exits Sunday night.

Terrain-enchanced lifting along with cooler temperatures will
support heavier snow totals across portions of the Adirondacks,
Green, and White mountains -- with several inches likely, as
indicated by the greater than 50 percent WPC probabilities for
accumulations over 8 inches.

While lesser amounts are more likely across the lower elevations,
guidance indicates that low-to-mid level frontogenesis may help
contribute to banded heavier snowfall rates (0.5-1 in/hr) that may
be sufficient enough to support a swath of heavier totals from
east of the western Maine mountains to Down East Maine on Sunday.
Higher probabilities for amounts over 4 inches have expanded across
this area and are now greater than 70 percent across a broader
area. Additionally, probabilities for totals over 8 inches have
increased in this area also, with some greater than 50 percent
probabilities near the Maine coast.

Pereira

$$

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FOUS11 KWBC 220714
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
314 AM EDT Sun Mar 22 2026

Valid 12Z Sun Mar 22 2026 - 12Z Wed Mar 25 2026

...Northeast...
Days 1-2...

Snow has begun falling across the northern Appalachians and
northern New England this morning as 850-700mb WAA aloft overruns a
boundary layer sufficiently cold enough to support snow. Snowfall
rates around 1"/hr are likely over the Green and White Mountains
this morning, where the combination of heavy rates and elevation
will support accumulating snowfall. Given the snow is unfolding
during the day, and boundary layer temperatures are more marginal
in the valleys, snowfall will be tougher to accumulate but still
cause some minor accumulations in the Champlain Valley and along
coastal Maine today. Snowfall will gradually taper off by Sunday
evening with light snowfall over Downeast Maine still unfolding.
There will still be cases where light snow ensues over northern New
England Sunday night and into Monday morning as a strengthening
500mb trough approaches from the west and low-level easterly flow
directs some Atlantic moisture into the region. Additional light
snow accumulations of a coating to 3 inches are possible through
Monday.

48-hour WPC probabilities show high chances (>70%) for >4" of
snowfall throughout southern Maine, the White and Green Mountains,
and the peaks of the Adirondacks. In the Green and White Mountains,
elevations above 2,000ft are likely to see snowfall totals range
between 8-12", with some localized peaks (such as Mount Washington)
potentially receiving over a foot of snow. The WSSI primarily shows
Minor Impacts (winter driving conditions; use caution) with locally
some Moderate Impacts (hazardous travel conditions) possible,
particularly in passes and complex terrain.


...Washington Cascades & Olympics...
Day 3...

A Pacific storm system will direct a plume of moisture at the
Pacific Northwest Monday night and into Tuesday that leads to
higher elevation snowfall. Snow levels initially starting out
between 4,000-5,000ft Monday night and early Tuesday will drop to
as low as 2,500ft in the Olympics and 3,000ft in the northern WA
Cascades. WPC probabilities show moderate-to-high chances (50-80%)
for snowfall totals >4" above 3,000ft in the Olympics and above
4,000ft in the WA Cascades north of I-90. At this moment,
Snoqualmie and Stevens Passes show low chances (<20%) for
accumulating snowfall >4", but some minor accumulations late
Tuesday into Tuesday night are possible.


The chances for significant ice across the CONUS is less than
10 percent.


Mullinax




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FOUS11 KWBC 221931
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
331 PM EDT Sun Mar 22 2026

Valid 00Z Mon Mar 23 2026 - 00Z Thu Mar 26 2026

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

While the primary precipitation shield associated with a clipper
system crossing the Northeast is forecast to begin moving offshore
this evening, a secondary period of accumulating snow is expected
on Monday. An inverted trough, extending back from the departing
low, is forecast to develop and linger across eastern New England.
This feature will likely act to focus a north-south oriented band
of snow showers that could intensify late Monday as an
intensifying shortwave and associated cold pool aloft pivot into
the region from the west.

Given the added lift and some modest instability, localized heavier
bursts are possible, especially in northern New Hampshire and
western Maine where the inverted trough may align with favorable
upslope flow. WPC probabilities indicate that an additional 2-4
inches are possible with this band, with the highest probabilities
(50-70+ percent) focused over the northern New Hampshire and
western Maine mountains.

...Washington Cascades & Olympics...
Days 2-3...

A deepening storm lifting from the northeastern Pacific into
British Columbia will bring widespread moderate to heavy
precipitation into the region on Tuesday. However, the heaviest
precipitation rates are expected to coincide with relatively high
snow levels through Tuesday afternoon. Consequently, the bulk of
the significant accumulating snow (greater than 8 inches) will
remain above the major passes and confined to the higher peaks of
the Olympics and the northern Cascades.

As the front crosses the region late Tuesday and early Wednesday,
snow levels will begin to plunge toward 3,000 ft, but this cooling
will occur as the deepest moisture begins to shift east. However,
some of passes may see a period of rain changing to snow, impacting
travel.


The chances for significant ice across the CONUS is less than
10 percent.

Pereira

$$

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FOUS11 KWBC 230726
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
326 AM EDT Mon Mar 23 2026

Valid 12Z Mon Mar 23 2026 - 12Z Thu Mar 26 2026

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

An inverted trough, extending back from the departing storm system
responsible for rounds of snow yesterday, will linger across
northern New England today. With sufficient low-level moisture off
the Atlantic and vertical ascent supplied by an approaching
shortwave trough to the west, periods of snow will continue over
the White Mountains. Some light snow is possible below 1,000ft, but
given the snow is occurring during daytime hours, snow will
struggle to accumulate on paved surfaces. WPC probabilities depict moderate-to-high chances (50-70%) for additional snowfall
accumulations >4" in the White Mountains, which included Mount
Washington. Otherwise, any additional snowfall accumulations below
2,000ft are likely to range between a coating-3".


...Washington Cascades & Olympics...
Days 1-3...

A strong and meandering closed upper low in the Gulf of Alaska will
direct a storm system forming on its southern flank at British
Columbia the first half of the week. With the Gulf of Alaska low
slow to move east and low level ridging in place off the southern
CA coast, low-level SWrly flow will supply a narrow corridor of
Pacific moisture into the Pacific Northwest Monday night and
through both Tuesday and into Wednesday. Snow levels will generally
reside above 3,000ft through Tuesday, but a cold frontal passage
and falling 700-500mb heights Tuesday night will cause snow levels
to dip to as low as 2,000ft by Wednesday. Still, the cold air in
wake of the cold frontal passage is not particularly cold, and the
best moisture advection will have already concluded by Wednesday.
This is likely to cause periods of mountain snow on Wednesday in
the Olympics and Cascades to as low as 2,000ft, but rates will not
be overly heavy even through Wednesday night.

WPC probabilities for >4" of snow are moderate-to-high (50-80%) for
elevations above 4,000ft north of I-90. Stevens Pass sports
moderate-to-high chances (50-80%) for snowfall totals >4" through
Wednesday night, while Snoqualmie Pass has moderate chances
(40-60%). Both passes sport low-to-moderate chances (20-40%) for
snowfall totals >8", so some locally hazardous travel conditions
are possible at pass level, but the heavier totals surpassing 8"
will likely be found at higher elevations for this event.


The chances for significant ice across the CONUS is less than
10 percent.


Mullinax




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FOUS11 KWBC 231844
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
244 PM EDT Mon Mar 23 2026

Valid 00Z Tue Mar 24 2026 - 00Z Fri Mar 27 2026

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

Latest surface analysis and RAP surface forecast indicate a defined
inverted trough axis bisecting NH up into neighboring Quebec with
some weak precipitation beginning to develop over far northern NH.
Expectation is for ascent to maximize within the trough axis later
this evening as flow focuses out of the north creating upslope flow
orthogonal to the terrain of the White Mountains leading to a
period of snowfall to develop as environmental conditions favor
frozen hydrometeors. Despite modest PWATs present over Northern New
England, the primary ascent pattern within the trough axis coupled
with upslope flow will generate localized moderate snowfall for
several hours creating a focal point of accumulating snow within
the White Mountains and some of the neighboring valleys. WPC
probabilities depict moderate- to- high chances (50-80%) for
additional snowfall accumulations >4" in the White Mountains, which
included Mount Washington. Otherwise, any additional snowfall
accumulations below 2,000ft are likely to range between a
coating-3".


...Washington Cascades & Olympics...
Days 1-3...

Little has changed from the previous forecast as the synoptic scale
pattern remains persistent within all guidance across the Pacific
Northwest. A strong and meandering closed upper low in the Gulf of
Alaska will direct a storm system forming on its southern flank at
British Columbia the first half of the week. With the Gulf of
Alaska low slow to move east and low level ridging in place off the
southern CA coast, low- level SWrly flow will supply a narrow
corridor of Pacific moisture into the Pacific Northwest later
tonight carrying through both Tuesday and Wednesday. Snow levels
will generally reside above 3,000ft through Tuesday, but a cold
frontal passage and falling 700-500mb heights Tuesday night will
cause snow levels to dip to as low as 2,000ft by Wednesday. Still,
the cold air in wake of the cold frontal passage is not
particularly cold, and the best moisture advection will have
already concluded by Wednesday. This is likely to cause periods of
mountain snow on Wednesday in the Olympics and Cascades to as low
as 2,000ft, but rates will not be overly heavy even through
Wednesday night.

WPC probabilities for >4" of snow are moderate-to-high (50-80%) for
elevations above 4,000ft north of I-90. Stevens Pass sports
moderate-to-high chances (50-90%) for snowfall totals >4" through
Wednesday night, while Snoqualmie Pass has moderate chances
(40-60%). Both passes sport low-to-moderate chances (20-50%) for
snowfall totals >8", so some locally hazardous travel conditions
are possible at pass level, but the heavier totals surpassing 8"
will likely be found at higher elevations for this event.


The chances for significant ice across the CONUS is less than
10 percent.


Mullinax/Kleebauer







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FOUS11 KWBC 240711
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
311 AM EDT Tue Mar 24 2026

Valid 12Z Tue Mar 24 2026 - 12Z Fri Mar 27 2026


...Washington Cascades & Olympics...
Days 1-2...

A strong and meandering closed upper low in the Gulf of Alaska
will direct a storm system forming on its southern flank at British
Columbia the first half of the week. With the Gulf of Alaska low
slow to move east and low level ridging in place off the southern
CA coast, low- level SWrly flow will supply a narrow corridor of
Pacific moisture into the Pacific Northwest today and into Wednesday.
Snow levels will generally reside above 3,000ft today, but a cold
frontal passage and falling 700-500mb heights Tuesday night will
cause snow levels to dip to as low as 2,000ft by Wednesday. Still,
the cold air in wake of the cold frontal passage is not
particularly cold, and the best moisture advection will have
already concluded by Wednesday. This is likely to cause periods of
mountain snow on Wednesday in the Olympics and Cascades to as low
as 2,000ft, but rates will not be overly heavy even through
Wednesday night.

WPC probabilities for >4" of snow are high (>70%) for elevations
above 4,000ft north of I-90. Stevens Pass sports high chances

70%) for snowfall totals >4" through Wednesday night, while

Snoqualmie Pass has moderate chances (50-70%). Stevens Pass poses
the slightly better odds for snowfall totals >8", ranging between
30-50%. Some locally hazardous travel conditions are possible at
pass level, but the heavier totals surpassing 8" will likely be
found at higher and more remote elevations.


...Northern Maine...
Days 2-3...

Starting Wednesday night, sheared lobes of 500mb vorticity racing
over the northern Great Lakes will generate PVA over northern New
England at the same time that low-level SWrly flow results in low-
level WAA and increased moisture content. Weak high pressure over
Quebec and sufficiently cold enough air over Maine will support
periods of snow over northern Maine with some minor icing possible
in central ME. As the first disturbance races east, a second 500mb
shortwave trough will spawn a second low over the northern Mid-
Atlantic Thursday evening. Periods of snow may envelope northern
Maine Thursday night as a cold front races south and forces
boundary layer temperatures to crash below freezing. There remains
some model spread in solutions regarding this second round of snow
Thursday night, so confidence in the snowfall placement and amounts
for the second round of snow is lower. At the moment, 48-hour WPC
probabilities show low chances (10-30%) for snowfall totals >4"
along the ME/Quebec border.


The chances for significant ice across the CONUS is less than
10 percent.


Mullinax





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FOUS11 KWBC 241849
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
249 PM EDT Tue Mar 24 2026

Valid 00Z Wed Mar 25 2026 - 00Z Sat Mar 28 2026


...Washington Cascades to Northern Rockies...
Days 1-2...

A shortwave trough rounding a deep, cold core low over the Gulf of
Alaska is directing an atmospheric river into the PacNW today with
high snow levels of 7000 to 8000ft. That trough axis approaches the
coast tonight before crossing the Cascades Wednesday and the
northern Rockies Wednesday night. Associated height falls drop the
snow level to 3500ft on the WA Cascades this evening before further
decreasing to around 2500ft Wednesday morning under the trough axis
(which is also when precip rates decrease). Snow probs for >6" are
40 to 80% above about 4000ft on the WA Cascades with some snow
getting down to 3500ft/Snoqualmie Pass level. Precip rates drop
off for the Cascades by Wednesday evening.

Farther inland, expect snow levels to decrease late tonight over
northwest MT and linger around 4000ft over northwest MT through
Wednesday. Day 1.5 snow probs for >6" are around 30% for the
highest Bitterroots and around 50% for the higher portions of the
Lewis Range in Glacier NP and the Mission Ridge which often stands
out for it's precip/snow forecast totals.


...Upper Midwest to Northern Maine...
Days 2-3...

Lee-side low development tonight in central Montana is expected
downstream of a trough axis approaching the Pacific Northwest. This
low tracks over Lake Superior Wednesday with snow generally in
Canada. However, it crosses Maine early Thursday producing moderate
snow over northern portions of the state. Day 2 snow probs for >4"
are limited to far northern NH terrain and only the higher points
of Maine.

A second and stronger wave crosses the northern Rockies Wednesday
night with an fgen band developing ahead over the northern Plains
early Thursday and shifts over the Northeast Thursday night. Some
snow mixed precip are likely with this band, though probabilities
are limited as of this time. The Day 2 ice probs for >0.01" are
40-70% from northern MN through the U.P. of MI.



Jackson


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FOUS11 KWBC 250707
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
307 AM EDT Wed Mar 25 2026

Valid 12Z Wed Mar 25 2026 - 12Z Sat Mar 28 2026

...Washington Cascades to Northern Rockies...
Days 1-2...

An approaching shortwave trough and an associated cold front will
track through the Pacific Northwest with upsloping winds and
sufficient Pacific moisture to produce mountain snow over the
Olympics and Cascades. Height falls and CAA in wake of a cold
frontal passage will cause snow levels to drop to as low as 2,500ft
this morning. Precipitation rates will gradually decrease
throughout the day, but persistent upslope flow will keep snow in
the forecast in the Cascades and Olympics as low as 2,500ft in
elevation through early Thursday morning. WPC probabilities depict
moderate chances (40-60%) for snowfall totals >4" at Snoqualmie
Pass and >8" at Stevens Pass. Most of the heaviest snowfall totals

8") will be confined to more remote elevations above 4,000ft.

Conditions at pass level should improve throughout the day Thursday
with snow concluding and higher late-March sun angles helping to
melt snow on paved surfaces.

Snow snow will spill east into the Northern Rockies as well, but
any accumulations will generally reside in the more remote
elevations (Glacier NPS the lone exception). Most snowfall amounts
will generally range between a coating to 3", but some locations
along the Lewis Range and Glacier NPS could see some localized
snowfall totals surpass 6" before snow concludes by Thursday
afternoon.


...Upper Midwest to Northern Maine...
Days 2-3...

A series of sheared 500mb vort maxima will generate light wintry
precipitation in portions of the Upper Midwest and northern Maine
the second half of the week. Focusing on northern Maine first, a
clipper system racing through southeast Canada Wednesday night will
escort a plume of moisture aloft within a corridor of 850-700mb
WAA over New England. Most of New England's boundary layer
temperatures will be too mild to support snow, with the lone
exception being far northern Maine. Snow will develop over northern
Maine late Wednesday night and linger through Thursday morning,
before finally ending Thursday afternoon. Snow fall rates will not
be overly heavy and the bulk of the snowfall will occur during the
day, which will limit snowfall totals thanks to the increasing
strength of the late March sun angle. Still, the border of Quebec
and northern Maine could still pick up some localized snowfall
totals >4" (WPC 24-hour probabilities show low-to-moderate chances
(20-40%). Some light snow may linger into Friday over the northern
Appalachians and northern Maine Friday morning as the next clipper
system passes well to the south.

At the same time as snow is unfolding across northern Maine on
Thursday morning, the next 500mb vort max is racing through the
Upper Midwest with a weak surface low tracking from eastern NE
into the heart of the MS Valley. Minor freezing rain and snow
accumulations will occur on the northern flank of the storm track
with WPC probabilities showing moderate-to-high chances (50-80%)
for >0.01" of ice accumulation from as far west as eastern ND to as
far east of the tip of Michigan's Mitt. It is worth noting WPC
probabilities for >0.1" of ice are <10%, so most ice accumulations
will be minor and struggle to accumulate on paved surfaces,
especially during the day on Thursday. The Huron Mountains are the
lone area where localized snowfall totals could top 2", but
otherwise the marginal boundary layer temperatures will make
snowfall more conversational rather than impactful on Thursday
morning.


The chances for significant icing across the CONUS is less than
10%.


Mullinax




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FOUS11 KWBC 251802
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
202 PM EDT Wed Mar 25 2026

Valid 00Z Thu Mar 26 2026 - 00Z Sun Mar 29 2026

...Washington Cascades to Northern Rockies...
Day 1...

Shortwave trough and associated cold front crosses the Cascades by
this evening with snow rates declining as snow levels fall from
3000ft to 1000ft. Day 1 snow probs for >4" are generally 30-60%
above about 3500ft.

Additional snow shifts east tonight through Thursday over the
Lewis Range in Glacier NP, the Bitterroots, Red Lodge portion of
the northern Absarokas in MT and the Bighorns. Day 1 snow probs are
30-50% across these areas of terrain.


...Northern Maine...
Day 1...

Weak low pressure over northern MI this afternoon strengthens as it
shifts across Maine on Thursday. WAA ahead of the low brings snow
to Maine late tonight/Thursday morning. Day 1 snow probs for >4"
are limited to far northern NH and the highest elevations and
northern border of Maine and generally 20-40%.


...Northern Plains and Upper Midwest...
Days 1 and 3...

A tight baroclinic zone develops tonight in zonal flow as low
pressure over the central Plains is met by strong high pressure
shifting from the Canadian Prairies. A wintry mix with generally
light rates develops along this boundary. Day 1 ice probs for

0.01" ice are 30-60% over eastern ND and across northern WI to

Upper MI, mainly falling late tonight through Thursday morning.
Little snow accum is expected.

High pressure shifting from the northern Plains to the Midwest
Friday through Saturday promotes some LES to develop off Lake
Superior on NW flow. Day 3 snow probs for >4" are 30-50% over the
eastern U.P.


The chances for significant icing across the CONUS is less than
10%.


Jackson



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FOUS11 KWBC 260716
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
316 AM EDT Thu Mar 26 2026

Valid 12Z Thu Mar 26 2026 - 12Z Sun Mar 29 2026

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

A weak area of low pressure and a trailing front will bring some
light snow to northern New England. Amounts will be light and
generally limited to the higher elevations due to marginal
temperatures. WPC probabilities for at least 4 inches of snow are
low, generally 10-20%, above 2000-3000ft or so.


...Upper Midwest and western Great Lakes...
Days 1-3...

A frontal boundary across the region has prompted some light icing
overnight that will continue this morning after 12Z, particularly
over northeastern WI, southern U.P. of Michigan, and into northern
Lower Michigan. WPC probabilities for at least 0.01" icing are
moderate (40-70%) in these regions, but are below 5% for amounts
higher than a tenth of an inch.

Colder air behind this system will move across the Great Lakes
Friday afternoon into Saturday, coincident with a mid-level
shortwave. With 850mb temperatures dipping to below -15C, some lake enhanced/effect snow is forecast for parts of the U.P. into
northern Wisconsin. Another weak shortwave Saturday evening will
bring another light dusting to an inch of snow to the U.P. of
Michigan. Amounts even across all three days should be light (1-2"
or so), and WPC probabilities for at least 4 inches are only 10-20%
for the period.



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


Fracasso

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FOUS11 KWBC 261933
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
333 PM EDT Thu Mar 26 2026

Valid 00Z Fri Mar 27 2026 - 00Z Mon Mar 30 2026

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

Low pressure lifting from northern New England into southeastern
Canada, along with a trailing front, will bring some light snow to
northern New England. Amounts will be light and generally limited
to the higher elevations due to marginal temperatures. WPC
probabilities for at least 4 inches of snow are low - capped at
10-20 percent and confined mostly to the far northern Green and
White mountains.

...Upper Midwest Great Lakes...
Days 2-3...

Cold air will continue to spread across the region as a mid-level
shortwave drops into the region by late Friday. With 850mb
temperatures dipping to below -15C, some lake enhanced/effect snow
is forecast for parts of region, with mostly light amounts
expected from northern Michigan to Upstate NY. Another weak
shortwave Saturday evening will bring another light dusting to an
inch of snow to the U.P. of Michigan. WPC probabilities indicate
that three-day snow accumulations will likely only be an inch or
two at most across the region.


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


Pereira


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FOUS11 KWBC 270707
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
307 AM EDT Fri Mar 27 2026

Valid 12Z Fri Mar 27 2026 - 12Z Mon Mar 30 2026

...Western Great Lakes...
Day 1...

Cold air (850mb temperatures around -15C) over the western Great
Lakes will support light snow across the region tonight as a mid-
level shortwave moves through the region this afternoon/tonight.
Amounts will be light (1-2") but could touch 4" over parts of the
U.P. of Michigan where WPC probabilities are near 10%.


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

Upper trough diving southeastward along the BC coast will move
into the Pacific Northwest on Sunday, bringing some mountain snow
to the Cascades and then into the northern Rockies along the
Divide. Colder air will rush in behind the cold front, allowing
snow levels initially near 2500-4000ft to fall to 1500-3000ft
overnight Sunday into early Monday (Cascades) but remain around
5000-600ft over northwestern MT. This will get some light snow to
the passes in WA, but probabilities for at least 4 inches of snow
are greater than 50% above about 4000-5000ft (Cascades) and 6000ft
over the Lewis Range.


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

Fracasso

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FOUS11 KWBC 271900
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Fri Mar 27 2026

Valid 00Z Sat Mar 28 2026 - 00Z Tue Mar 31 2026

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

Guidance maintains general run-to-run continuity for the next
disturbance to impact the Northwestern U.S. by the end of the
weekend. Upper trough diving southeastward along the BC coast will
move into the Pacific Northwest on Sunday, bringing some mountain
snow to the northern Cascades and then into the northern Rockies
along the Divide. Colder air will rush in behind the cold front,
allowing snow levels initially near 2500-4000ft to fall to
1500-3000ft overnight Sunday into early Monday (Cascades) but
remain around 5000-600ft over northwestern MT. This will get some
light snow to the passes in WA, but probabilities for at least 4
inches of snow are greater than 50% above about 4000-5000ft
(Cascades) and 6000ft over the Lewis Range.


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

Fracasso/Kleebauer




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FOUS11 KWBC 280647
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
247 AM EDT Sat Mar 28 2026

Valid 12Z Sat Mar 28 2026 - 12Z Tue Mar 31 2026

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

A closed low south of the Gulf of Alaska will continue
southeastward today and slowly weaken into a positively-tilted
upper trough as its cold front moves through WA/OR on Sunday.
Despite some injection of mid-latitude Pacific moisture, the system
will be progressive and QPF will be limited. Snow levels will be
on the lower side -- 2500-4000ft in the Cascades before lowering
further behind the front to 1500-3000ft. This will bring some snow
to the passes and probabilities for at least 6 inches are at least
50% above about 3000ft or so for the northern Cascades.

Farther east, moisture will stream into the northern Rockies and
eventually into northern/northwestern Wyoming Sunday evening
through Monday and overnight into very early Tuesday, ending from west/northwest to east/southeast. Amounts will again be generally
light, with probabilities of at least 6 inches at least 50% above
about 5000ft in ID/MT but above 9000-10,000ft in WY.

Front end of the precip shield advancing across the Northern
Plains could support some light icing over northern ND early Monday
with generally a few hundredths of an inch possible.


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

Fracasso


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