Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
343 AM EST Tue Nov 22 2022

Valid 12Z Tue Nov 22 2022 - 12Z Fri Nov 25 2022

...Northwest...
Day 1...

Potent, fast-moving warm advection precipitation ahead of a
shortwave trough approaching the WA coast will spread over
WA/northern OR today with snow levels around 6000ft west from the
crest of the Cascades. Snow levels drop below 4000 ft across the
region as the associated cold front that pushes through the region
tonight. Day 1 snow probabilities are moderate to high for 6 or
more inches for the WA Cascades and only the highest OR Cascades.
East of the crest in the WA portion of the Columbia Basin, shallow
low level cold air is expected to remain, raising the threat for
measurable glazing from freezing rain. Day 1 WPC ice probabilities
are 20 to 40 percent for a tenth inch of ice or more across much
of the Washington Columbia Basin. 


...Rockies...
Days 1-3...

The shortwave trough is forecast to amplify and move southeast
down the length of the Rockies tonight through Thursday. This fast
moving system loses connection to much Pacific air and the
continental air it has to work with is rather dry. Moderately high
Day 1 probabilities for 4 or more inches are across northern ID
and the higher western MT ranges. Day 2 probabilities are low to
moderate for a few ranges in central/eastern WY with only light
snow forecast in CO.


...Southern Plains...
Day 3...

Global consensus is now for the amplifying trough to take on a
strong positive-tilt Thursday over the southern Rockies and pinch
off as a cutoff upper low over TX Thursday night. This stalled low
would be able to draw considerable Gulf moisture around with
mesoscale bands of snow on the NW side of the upper low over the
TX Panhandle into eastern NM. As of now the Day 2 snow
probabilities are 10 to 30% for 2 or more inches in portions of
these areas, though confidence should only increase in placement
and intensity of these snow bands with subsequent runs.


Jackson