Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
329 PM EDT Fri Oct 24 2025

Valid 00Z Sat Oct 25 2025 - 00Z Tue Oct 28 2025


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

A deep low remains over the Gulf of Alaska through Saturday night.
An initial shortwave trough, which has been directing an
atmospheric river (AR) into eastern OR/WA today, crosses the coast
this evening bringing rapidly falling heights and cooler
conditions. Snow levels drop from around 8000ft currently to around
5000ft on the OR/WA Cascades by 06Z with heavy snow limited to the
higher Cascades. The QPF will then have brief reprieve overnight
from minor ridging ahead of the main shortwave trough axis that
crosses the OR/WA coast midday Saturday. The second surge in
moisture arrives as a thump Saturday morning ahead of that second
axis with snow levels around 4000ft in WA, 5000ft in OR, and 7000ft
in northern CA and the Sawtooths of ID which are in the AR axis.
This surge then progresses inland, reaching the MT Rockies Saturday
evening and overnight for the western WY Rockies.

A third shortwave trough axis crosses the OR/WA coast midday Sunday
with slow ridging then through Monday in continued onshore flow.
Snow levels decline through Sunday, reaching 3500ft from WA through
western MT, 4500ft from OR through northwest WY, and about 5000ft
in northern CA. Therefore this will be a long- lasting event with
drawn- out impacts. The heaviest snow is expected on the Cascades
which are orthogonal to the onshore flow. Moderate impacts become
likely across the higher Cascades passes including Stevens and
Santiam Saturday night.

Day 1.5 (Saturday/Saturday night) WPC snow probabilities for >12"
are 40-70% for the higher Cascades and Sawtooths with similar
percentages for >24" in the highest Cascades.

Day 2.5 probs for an additional >6" are 40-70% for the Cascades,
Bitterroots and Sawtooths, as well as the Absarokas/Tetons, and
Wind Rivers. Snow levels decrease to around 7000ft in southern
WY/northern CO Sunday night with moderate rates and Day 3 snow
probs of 20-40% in the Park Range of CO.


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

Jackson