Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
341 AM EDT Thu Nov 02 2023

Valid 12Z Thu Nov 02 2023 - 12Z Sun Nov 05 2023

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

An atmospheric river shifts inland over the Pacific Northwest
today ahead of a low off the northern top of Vancouver Island.
Right entrance region associated lift from a NWly jet from
Saskatchewan to the eastern Dakotas combines with topographical
lift to limit the rise of snow levels over the Northern Rockies as
moderate to locally heavy precip spreads across the Northwest
today. Snow levels are kept from getting above 7000ft today on the
Absarokas and Grand Tetons where 6-12" are likely at the highest
elevations.

Day 3...
Zonal flow and a mid-level ridge axis reaching the PacNW coast
Friday morning, cutting off onshore flow and a quick end to
precip/lull for Day 2. However, another atmospheric river ahead of
the next wave in the active pattern for the Northwest arrives to
the PacNW coast on a potent jet Friday night. This zonal pattern
features a baroclinic zone over the Northwest with high snow
levels over Oregon/southern Idaho. Moderate precip arrives into
the Absarokas Saturday night with 30% or so changes for 4" by 12Z
Sunday.


The probability of significant icing is less than 10%.


BryanJ