Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
327 PM EST Mon Jan 04 2021

Valid 00Z Tue Jan 05 2021 - 00Z Fri Jan 08 2021

...Pacific Northwest/California/Northern Rockies...
Days 1-3...

Sharp and amplified shortwave currently working through the
Pacific NW will bring heavy snowfall primarily to the OR/WA
Cascades and further east toward the Sawtooth and Blue Mountain
ranges. By tonight into early Tuesday, this wave will have
traversed the Rockies and its moisture axis and forcing weakened,
giving way to a lull in the heaviest precipitation across the
region. WPC probabilities are moderate for 8 inches or more this
evening/tonight, highest across the WA Cascades.

Another impulse then quickly moves in late Tuesday into Wednesday
with another impressive atmospheric river event. Another round of
sufficient moisture and lift will result in heavy precipitation.
The best orographic lift and focus for heavy snow appears to be
the WA Cascades and perhaps south into OR. WPC probabilities
continue to be high for 12 inches or more for the WA Cascades.


The probability of significant icing (0.25" or more) is less than
10 percent all 3 days.

Taylor