Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
253 PM EDT Sat May 2 2026

Valid 00Z Sun May 03 2026 - 00Z Wed May 06 2026

...Sierra Nevada...
Days 2-3...

Broad upper low near 40N/130W (west of NorCal) this evening will
continue southward overnight then turn eastward and move into
central CA late Sunday night/early Monday. Modest moisture plume
will be focused south/east of the Sierra, but incoming height falls
and upslope will still yield light to modest snow for the High
Sierra starting Sunday afternoon. Snow levels will be high to start
(>9000ft) but then trend lower to around 7000-8000ft as the upper
low approaches and slowly passes through the region overnight
Monday into Tuesday. By the end of this forecast period, the upper
low is forecast to be nearing the Grand Canyon with lingering snow
over the Sierra and rising snow levels. WPC probabilities for at
least 6 inches of snow are >50% above about 8000-9500ft (north to
south).


...Wyoming and Colorado...
Day 3...

In response to building ridging into NW Canada Monday morning,
troughing will sink into the Northern Plains and the Great Lakes
with an attendant and strong cold front racing southward from
Montana into Wyoming. At the same time, the upper low over CA will
continue to favor SW flow across the Four Corners as the upper jet
arcs into the region. Precipitation will expand across WY and CO
Monday into Tuesday ahead of the cold front with high snow levels
initially >9000-10,000ft. By early Tuesday, cold front will push
southward through WY and eastern CO with snow levels lowering to
6000-7000ft behind the boundary that may slow and hang up along the
Divide, keeping snow levels >8000ft on the west side. Modest to
locally heavier snow could set up over parts of southern WY into
northern CO via easterly/upslope flow (e.g., Laramie and Medicine
Bow Mountains) with additional modest snow over the Bighorns and
Wind River Range. Snow will continue past the end of this forecast
period. Through 00Z Wed, WPC probabilities for at least 6 inches of
snow are >50% above 8000-9500ft in northern WY and above
8500-10,000ft in CO. For at least 2 inches of snow, WPC
probabilities are >50% to as low as 7000-8000ft along the WY/CO
border through the Medicine Bow Mountains.


The probability for significant icing over one-tenth of an inch is
less than 10 percent across the CONUS.


Fracasso