858
FOUS11 KWBC 011944
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
344 PM EDT Sat Nov 1 2025

Valid 00Z Sun Nov 02 2025 - 00Z Wed Nov 05 2025

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

An expansive trough extending from a deep/cold-core low centered
over the Gulf of Alaska continues to dominate the northeast Pacific
weather pattern through tonight. A shortwave trough rounding the
low is pushing into Vancouver Island this afternoon which will
cross Washington state through this evening and bring snow levels
down from 8000ft at present to around 3500ft which is at or below
most Washington Cascades pass levels. This occurs as continued
onshore flow maintains moderate precip rates on the western slopes
of the Cascades. 12Z HREF indicates mean snow rates of 1-2"/hr over
the higher Cascades between 06Z and 12Z tonight. Day 1 WPC snow
probabilities for >6" are 50-80% generally above the pass level.
Precip quickly tapers off Sunday morning as ridging builds in the
wave of the shortwave trough passage. A subsequent round of light
snow with snow levels of 3500-4000ft can be expected over the
Washington Cascades Monday night.


...Northern Rockies...
Day 3...

A shortwave trough pushes in from the OR coast Monday night along a
decent baroclinic zone over the Interior Northwest. Light to
moderate precip rates can be expected over the northern Rockies
with snow levels around 5000ft in the Bitterroots to 8000ft for the
Sawtooths in ID and around Yellowstone. Day 3 WPC snow
probabilities for >6" of 20-40% are limited to the higher portions
of this terrain.



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

Jackson



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