Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
403 PM EDT Fri Sep 29 2023

Valid 00Z Sat Sep 30 2023 - 00Z Tue Oct 03 2023

...Sierra Nevada through the Northern Rockies...
Days 1-3...

A mid-level shortwave trough currently situated near the northern
California coast early Friday afternoon is forecast to amplify
further going into Saturday, and likely evolving into a closed low
by Saturday night and into Sunday across northern Nevada.  In
terms of winter weather potential, the winner of highest potential
snowfall totals goes to the central Sierra, where snow will begin
during the early morning hours Saturday and last through late
Saturday evening.  This will be associated with low-mid level
moisture advection oriented nearly orthogonal to the Sierra.  Snow
levels should be in the 8000-9000 foot range, and accumulations on
the order of 4 to 8 inches are expected along the higher ridges,
generally above tree line.  There may be some lingering snow
showers going into Sunday as well with some instability associated
with the upper low nearby.

Attention then turns to the highest mountain ranges of the
Intermountain West going into Sunday and early Monday as the upper
low reaches northeastern Nevada and southern Idaho.  It appears
the Uinta Mountains will likely get the greatest snowfall totals
for this time period, with some 6+ inch accumulations possible
here above 9000 feet where the 700mb flow is oriented more
orthogonal to the terrain.  A few inches of snow is also likely
for the highest ridges of the Wasatch, Wind River, Absaroka, and
Bitterroot Mountains.


The probability of any ice accumulation across the Continental
U.S. is less than 10 percent.


Hamrick