Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
500 AM EDT Sun Oct 26 2025

Valid 12Z Sun Oct 26 2025 - 12Z Wed Oct 29 2025


...Pacific Northwest to the Central Rockies...
Days 1-2...

The primary shortwave axis will be positioned well inland, near
the Northern Rockies, to begin the period /12Z Sunday/, but a
secondary impulse and accompanying surface wave will move onshore
near the OR/CA border this evening. The accompanying pinched and
confluent mid-level flow will continue to advect higher moisture
onshore, leading to a second wave of heavy precipitation moving
from the Cascades early today into the Northern Rockies by early
Monday.

This second wave of precipitation will occur behind the primary
cold front, and during a period of continued height falls, so snow
levels will fall steadily through D1. The latest NBM snow level
forecasts have trended downward, reaching as low as 2000 ft in the
eastern Cascades, to around 3500 ft in parts of OR/MT/ID. This will
occur in tandem with waves of precipitation, such that even though
precipitation intensity may be less than what occurred Saturday,
pass level impacts will be more substantial due to the lower snow
levels. This wave moves quickly east, however, and by Monday night
precipitation should generally wane across the region.

WPC probabilities are high (>70%) for 6+ inches across the Cascades
and into portions of the Salmon River ranges D1 before waning
quickly during D2. Passes will likely become hazardous D1 due to
low snow levels, especially around Stevens and Santiam Passes in
the Cascades.


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


Weiss