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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