Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
218 AM EST Thu Nov 19 2020

Valid 12Z Thu Nov 19 2020 - 12Z Sun Nov 22 2020


...Pacific Northwest/Northern Rockies...
A series of shortwaves moving through a broad upper trough will
continue to support showers, including high elevation snow, with
locally heavy accumulations through Thursday.  Areas impacted
include the Olympics, Washington and northern Oregon Cascades, as
well as the portions of the northern Idaho, northwestern Montana
and western Wyoming ranges.  WPC PWPF shows high probabilities for
additional accumulations of 4-8 inches, with some potential for
locally higher totals across these areas. 

Threat for heavy snow is expected to diminish on Friday, with dry
conditions expected on Saturday as a shortwave ridge moves across
the region.

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

Pereira