Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
159 PM EDT Tue Oct 22 2024

Valid 00Z Wed Oct 23 2024 - 00Z Sat Oct 26 2024

...Vicinity of Yellowstone NP...
Day 2...

A compact shortwave will amplify as it races eastward from OR into
the Central Rockies Thursday, combining with a sharpening jet
streak in the base of the accompanying trough to produce large
scale ascent downstream. Lift through height falls, PVA, and upper
diffluence will move into ID/WY/MT Thursday morning, impinging upon
a modest surge of 700mb RH and PWs which briefly exceed +1 sigma
according to the NAEFS ensemble tables. At the surface, a wave of
low pressure will develop beneath this shortwave and along a cold
front pushing eastward, leading to additionally enhanced lift
through convergence and upslope flow. This will result in an axis
of expanding precipitation, with snow levels falling from around
8000 ft to 5000 ft before precipitation wanes Thursday evening, and
WPC probabilities for more than 4 inches of snow peak around 30%,
highest in the Tetons and southern Absarokas.

The probability of significant ice across the CONUS is less than
10 percent.

Weiss