Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
423 AM EDT Fri Oct 15 2021

Valid 12Z Fri Oct 15 2021 - 12Z Mon Oct 18 2021


...Pacific Northwest/California...
Day 3...
An amplifying ridge is expected to support dry conditions, with
seasonal to above-normal temperatures for most areas west of the
Continental Divide on Friday into Saturday.  Then by late
Saturday, an approaching amplifying trough off of the Pacific
Northwest coast will bring a frontal boundary and precipitation
back into western Washington and Oregon.  Models show the upper
trough continuing to amplify and move east on Sunday into Monday
-- driving the cold front steadily east while bringing light to
moderate precipitation across much of western Washington and
Oregon, and northern California.  Snow levels are expected to be
around 6000-7000 ft Sunday morning, but drop to 4000-5000 ft
Sunday night behind the front -- resulting in some isolated areas
of heavy snow across the Cascades and the northern Sierra Nevada.

For Days 1-3, the probability of significant icing (0.25 inch or
more) is less than 10 percent.

Pereira