Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
305 AM EDT Sun Oct 11 2026

Valid 12Z Sun Oct 11 2026 - 12Z Wed Oct 14 2026

...Northern Rockies...
Day 1...

Banded snow will continue through the day today over western
Montana into the high terrain of western Wyoming as the upper low
over WA/OR slowly sinks southward and narrows. This will maintain
SW flow over the Northern Rockies and eventually help to bring
northward the remnant moisture of Rachel by this evening/overnight.
Snow rates of about 0.5"/hr will continue through the day but
increase later tonight over MT with the additional moisture surge
when 1"/hr rates will again be possible after Saturday's initial
snowfall. By Monday morning, heights will rise slightly over the
region as the upper low digs farther into CA/NV, largely ending the
snow over the region.

WPC probabilities for an additional 6 inches of snow are >80%
along the eastern slopes of the Lewis and Flathead Ranges then east
over the Belts, and 50-70% in the adjacent terrain down to around
3800ft MSL.

Into WY, higher snow levels will limit accumulations to the high
Wind River Range and Absarokas where an additional 1-2ft of snow is
likely.


...Sierra Nevada/Great Basin Ranges/Utah Ranges/Southwest CO...
Days 1-3...

The upper low over OR will sink southward today and dig into CA/NV
as the remnant Rachel moisture zips northeastward. Light snow is
expected for only the highest peaks. By Monday, as heights start to
fall, snow levels will drop to 6000ft as moisture increases over
the Sierra and especially across the Great Basin to Utah. As the
upper low turns eastward across NV into UT, snow will spread
eastward into western CO but with high snow levels around 11,000ft.
Still, the combination of height falls, abundant moisture, and
orographic upslope will yield modest snow for the high terrain
through early Wednesday. The Unitas may see 1-2ft with at least 8
inches likely (>70% chance) above 9000ft or so across NV and
10,000ft across central/southern UT. Light snow will overspread the
San Juans in SW CO Tuesday and continue through the end of the
period with >50% chance of at least 4 inches above 11,000ft.

The probability of significant ice across the CONUS Days 1-3 is
less than ten percent.


Fracasso