Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
255 PM EDT Mon Oct 27 2025

Valid 00Z Tue Oct 28 2025 - 00Z Fri Oct 31 2025


...Northern/Central Rockies...
Day 1...

Remaining moisture on the backside of a departing trough will
wring out a few more inches of snow tonight over northwestern
Montana where WPC probabilities for at least another 4 inches of
snow after 00Z/28 are low (<40%).


...Washington Cascades...
Day 2...

A rapidly-deepening and strong closed low over the northeastern
Pacific tonight/Tuesday will start to weaken as it moves ashore
British Columbia tomorrow night. Mild temperatures will flood the
Pacific Northwest ahead of the cold front with snow levels as high
as 8000-9000ft 06Z Wednesday. However, snow levels will crash quite
smartly by 12Z as precipitation starts to decrease and end by the
conclusion of day 2 (00Z/30). There will be a brief but impressive
period of heavy snow invading lower elevations (down to about
4500ft) which will impact the higher Washington Pass/SR-20. WPC
probabilities for at least six inches of snow are >50% above about
5000ft depending on how quickly snow levels fall coincident with
moderate QPF.


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

Fracasso