Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
202 AM EST Fri Feb 23 2024

Valid 12Z Fri Feb 23 2024 - 12Z Mon Feb 26 2024

...Pacific Northwest to the Northern Rockies...
Days 2-3...
Dry weather is expected to continue for much of the region through
at least early Saturday before increasing onshore flow/moisture
advection begins to fuel precipitation spreading south along the
northern Cascades and the northwestern Montana Rockies.  The
extent of impactful snow is expected to remain limited through
early Sunday, but may include some of the passes, as snow levels
fluctuate around 3500-4000 ft. 

Heavy snow is expected to become more widespread by late Sunday
and continue into Monday as a highly-amplified shortwave trough
drops through British Columbia into the region.  Heavy snow is
forecast to cover the Olympics while spreading south along the
Washington into the Oregon Cascades and along the northern Idaho
and northwestern Montana Rockies.  Snow accumulations of a foot or
more are likely for Snoqualmie and Stevens passes, while multiple
feet can be expected in the higher elevations of the northern
Cascades.  Light accumulations are possible in the lowlands as
snow levels drop below 500 ft in western Washington behind a
well-defined cold front.  In the northern Idaho and Montana
ranges, widespread accumulations of 6 inches or more are likely,
including both Lookout and Marias passes, with a foot or more
expected in some of the higher elevations.  In addition to heavy
snow, this system is forecast to bring strong, gusty winds to the
region.

The probability of ice accumulations of 0.10 inch or more is less
than 10 percent.

Pereira