Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
255 AM EDT Sat Sep 30 2023
Valid 12Z Sat Sep 30 2023 - 12Z Tue Oct 03 2023
...Sierra Nevada through the Northern Rockies...
An amplifying shortwave trough, digging over northern California
will close into a low tonight and into Sunday over western Nevada.
Pacific moisture streaming ahead of this trough is progressing
down the Sierra Nevada this morning with snow levels between 8000
and 9000ft. As the surface reflection develops over the Great
Basin today, an easterly component brings a precip focus to the
eastern slopes of the Sierra Nevada as well as the ranges of
Nevada and the White Mtns which extend into CA with similar snow
levels where there are moderate probabilities of 4"+. Snow showers
reinvigorate diurnally Sunday from instability associated with the
nearby upper low.
Meanwhile, slow eastward progress of the low on Sunday brings
precip across the rest of the Intermountain West including Utah
Idaho and Wyoming. The large and tall Uinta Mountains will likely
get the greatest snowfall totals for the Sunday/Monday time
period, with 6-10 inch accumulations likely above 9000 feet where
the 700mb flow is oriented more orthogonal to the terrain. A few
inches are also expected for the highest portions 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.