Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
328 AM EDT Fri Nov 03 2023

Valid 12Z Fri Nov 03 2023 - 12Z Mon Nov 06 2023

...Northwest to Northern Rockies...
Days 2/3...

A ridge axis shifts east from the Pacific Northwest coast today,
crossing the northern Rockies tonight with a lull in precip under
the height rises. Onshore flow resumes tonight as the next
atmospheric river reaches the Pacific Northwest coast on a strong
zonal Pacific jet that lingers near the Oregon/California border
through the weekend. PWATs of 1.75" reach the coast tonight with
1-2 sigma above climatology moisture spreading inland over the
Northwest to the Northern Rockies through Saturday. Snow levels
are high in this potent atmospheric river, around 10,000ft, but
drop to around 6000ft starting at the coast Saturday afternoon
under the upper trough axis. Day 2 snow probabilities are limited
to the highest Cascades. Continued onshore flow and lowering
heights/snow levels bring moderate snow back to Northwest Wyoming
Saturday night/Sunday with 20 to 50% Day 3 probs for >4" in the
Absarokas.

The active pattern over the Northwest continues into next week as
a series of shortwave troughs cross the Northwest on this strong
zonal jet, with snow levels dipping down to 5000ft Monday.


...Northern North Dakota...
Day 3...

Warm air advection up the Plains on return flow ahead of an
approaching trough Saturday night/Sunday overruns cold air over
northern North Dakota, bringing a risk for freezing rain up along
the Canadian border. Day 2.5 ice probabilities for a tenth inch
are 10 to 20% there.


Jackson