Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
334 PM EST Wed Jan 29 2020

Valid 00Z Thu Jan 30 2020 - 00Z Sun Feb 02 2020


Days 1-3...

...Pacific Northwest to the Northern Rockies...
A shortwave trough and a weakening frontal system are expected to
move east across the Northwest into the northern Rockies Wednesday
night.  This system is expected to produce mainly light
precipitation from the Northwest to the High Plains, with little
threat for heavy snow or significant ice.

Heavy precipitation is forecast to return to western Washington
beginning late Thursday.  Models show a warm front lifting north
along the coast as strong westerly flow aloft begins to direct a
long fetch of deep moisture inland.  However, snow levels will be
increasing, with heavy snows largely confined to areas above
6000ft in the northern Cascades.

Low pressure over the eastern Pacific on Friday is forecast to
track north of Vancouver Island into northern British Columbia
Friday night.  Deep southwesterly flow ahead of the trailing cold
front will bring additional heavy precipitation into western
Washington late Friday into Saturday.  Snow levels will remain
high until late in the period when the front begins to move inland
-- expanding the threat for heavy snow along the northern
Cascades.  

The probability of significant icing (0.25-inch or greater) is
less than 10 percent.

Pereira