FOUS11 KWBC 241929

QPFHSD



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





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