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FOUS11 KWBC 230758
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
258 AM EST Sun Nov 23 2025

Valid 12Z Sun Nov 23 2025 - 12Z Wed Nov 26 2025


...Southern Rockies...
Day 1...

An upper-low over central AZ this morning will move across the
Four Corners and through Colorado later today. Diffluent flow atop
a robust subtropical moisture feed will promote snow across the San
Juans and Sangre de Cristos, aided by upslope enhancement as the
upper low approaches. Snow levels will be high -- generally above
9000ft initially then dropping to around 7000ft as precipitation
ends early Monday. WPC probabilities for at least 8 inches of snow
are >50% above about 11,000ft in the more remote/higher ridge lines
of the San Juans and Sangre De Cristo range.

...Pacific Northwest & Northern Rockies...
Days 1-2...

A Pacific disturbance embedded within quasi-zonal flow will usher
in a progressive, but potent, frontal system into WA/OR/ID and
northwestern MT this morning. As the cold front traverses the
Pacific Northwest, snow levels around 5000-6000ft this afternoon
will drop to as low as 2,000ft on the windward side of the Cascades
by early Monday as precipitation begins to taper off. This would
affect many of the passes with at least some snow, and WPC
probabilities for >4" of snow are between 30-50% in both Stevens
and Snoqualmie Passes.

Farther east, snow will also spread across northern ID into
western MT later today through Monday as moisture associated with
the Pacific system passes through. Minor snowfall accumulations
(1-4") are possible as far south as the Tetons and Big Horns. The
focus for the heaviest snowfall resides along the Lewis Range on
Monday as snowfall rates become enhanced by easterly upslope flow
due to strengthening high pressure over southwest Canada. Snowfall
rates nearing >1"/hr are possible at higher open passes (e.g.,
Marias Pass). Snow should taper off across all of the northern
Rockies by early Tuesday morning. WPC probabilities for >8" of
snowfall are >70% across the Lewis Range above 5,000ft. In the
highest elevations of the Lewis Range (>6,000ft), WPC probabilities
show moderate chances (40-70%) for snowfall totals >12". The WSSI
does show mostly Minor Impacts in the Lewis Range, the Bitterroots,
and the Crazy Mountains.

...Northern Cascades/Olympic Peninsula...
Day 3...

The next Pacific system will move into western Washington on
Tuesday on a 120kt jet. Cold air in place could support some spotty
freezing rain along/east of the crest as warmer air aloft moves
in. Snow levels will slowly rise as the warm front lifts through
overnight into early Wednesday, but may be loathe to budge east of
the Cascades until later on Wednesday. With a fairly long moisture
fetch into the Pacific, precipitation amounts could be at least
modest, suggesting impactful snow even at Snoqualmie Pass. Through
12Z Wednesday, WPC probabilities of at least 6 inches of snow are
>50% above about 5000ft.


...Northeast...
Day 1...

A clipper system rotating beneath the base of an broad upper-low
over Quebec will push quickly through northern NY/New England this
afternoon/evening and exit to the east by Monday morning. QPF and
the resulting snowfall will be somewhat limited due to its fast
movement and the clipper being relatively moisture-starved, but
some upslope enhancement may allow for anywhere between 1-4" of
snow across the Tug Hill, Adirondacks, and the Green and northern
White Mountains. WPC probabilities for at least 4 inches of snow
remain on the lower side (10-40%) in these areas generally above
1500-2000ft in the Adirondacks and Tug Hill, with the highest peaks
showing a slightly higher change (50-60%) of at least 4 inches of
snow. Still, some snow covered roads could make for slippery
driving conditions tonight and Monday morning.


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

The shortwave trough responsible for the snow across the Northern
Rockies to start the week moves into the northern High Plains on
Monday night. By early Tuesday, a sharpening of the jet will allow
the mid-level shortwave to deepen and close off (at least briefly)
as it remains progressive. WAA and lower-level FGEN will support a
stripe of light to modest snow across ND as a surface low deepens
along the ND/SD border. It will then continue to strengthen and
lift northeastward through MN into the western Great Lakes, with
sufficiently cold air on its northwest side for a broad area of
snow. The wrapped-up system could form a TROWAL across northern MN,
favoring a region of heavier snow. The models disagree on the
location and amount of QPF (and thus snow), but the potential
exists for an axis of appreciable snow late Tuesday into Wednesday
(and beyond for the western Great Lakes).

Through 12Z Wednesday, WPC probabilities for at least 4 inches of
snow are >50% from northeastern MT across much of ND and northern
MN. Within this region, probabilities for at least 8 inches of snow
are 30-50% over central ND and northern to northeastern MN.
Blowing snow may become a hazard as winds increase in response to
the deepening low pressure. Interests in the Northern Plains and
Upper Midwest should keep a close eye on the forecasts from their
NWS WFOs and WPC in the coming days given this storm could prove a
headache for those traveling in the lead up to Thanksgiving.


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

Fracasso/Mullinax


$$