Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
356 AM EST Thu Dec 19 2019

Valid 12Z Thu Dec 19 2019 - 12Z Sun Dec 22 2019

...Northwest...

Days 1-3...

An active weather pattern will be in place across the West Coast
region for the end of the week and into Saturday as an atmospheric
river event is expected. Snow levels will initially be low early
in the event (4000 ft or less), but are forecast to rise
Thursday-Friday -- reaching 6000 feet or greater across the
Cascades from southern WA southward through northern CA by
Thursday night. The heaviest snowfall this period is for the
Washington Cascades and Olympics -- on the order of 1 to 3 feet
over the higher elevations with isolated higher maxima across the
highest peaks. A transition from snow to rain is expected for the
lower terrain of the Cascades owing to the warm air advection, and
this will greatly reduce the total snowfall accumulation. Heavy
snow on the order of 1 to 2 feet also appears likely for the
higher terrain of extreme northern Idaho and northwest Montana
during, much of which will fall through Thursday night.

The probability for significant freezing rain is less than 10
percent all 3 days.

Hurley