Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
259 AM EST Thu Nov 6 2025

Valid 12Z Thu Nov 06 2025 - 12Z Sun Nov 09 2025

...Pacific Northwest through the Northern Rockies...
Days 1-2...

The next shortwave trough passage over the Pacific Northwest is
this evening as a potent wave crosses Washington, reaching mid
Montana Friday morning. Warm/moist advection ahead of the wave
raises snow levels on the Washington Cascades from 5000ft to
6500ft through this afternoon before sharply dropping to 4000ft
overnight as precip rates slowly subside post axis passage. Day 1
WPC snow probabilities for >6" are 40-80% generally above the
higher WA Cascade road passes.

Pacific moisture surges inland over the northern Rockies tonight
into Friday. However, snow levels rise only to around 6000ft
tonight before dropping to around 4500ft under the trough on
Friday. Day 1.5 WPC snow probabilities for >6" are generally
30-60% over the higher terrain of the Salmon River Mtns of ID, the
Bitterroots, and the Lewis Range of Glacier NP and 50-80% for the
Tetons.


...Northern Plains to Great Lakes...
Days 2-3...

Potent shortwave trough from the Pacific pivots from an eastward
trajectory to southeasterly Friday night over eastern Montana. This
trough then swings through Iowa later Saturday before being
reinforced over the Great Lakes Saturday night by a Canadian
trough dropping south. By Saturday morning, modest frontogenetic
snowfall is expected to develop near the MT/ND border which is
along the northwest flank of the surface low center. This wave is
fairly progressive and working with marginal thermals. Day 2.5 WPC
probabilities for >2" are 10-50% in a stripe across ND. The
reinforcing trough could aid some more notable snow banding along
the IA/MN border and trigger some lake enhanced snow, including
over central MI where Day 3 snow probs for >4" are around 30%.
Locally hazardous travel conditions could materialize owing to
strong gradient winds on the periphery of the low and some areas
experiencing their first snow of the season.


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


Jackson