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

Valid 12Z Sat May 02 2026 - 12Z Tue May 05 2026

...Sierra Nevada...
Days 2/3...

A large, but modest amplitude mid-level low will swing onshore
central California Sunday night and drift to southern CA through
Monday night. Upslope precip begins Sunday afternoon, but snow
levels will be around 9500ft before dropping to around 8000ft late
Sunday night. Snow levels will then be around 7500ft under the low
on Monday when the precip should be the most consistent. Day 3 snow
probs for >6" are generally 40-70% for the High Sierra.


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

Low pressure swings through western Ontario Sunday night with a
potent cold front sweeping down the Northern Plains in its wake.
A digging mid-level trough behind the front provides lift over an
existing frontal boundary ahead of the aforementioned low moving
over CA before the cold front shunts activity a bit farther south
on Tuesday. There is uncertainty in the placement of this frontal
zone with the GFS farther north in central WY and the EC remaining
farther south along the WY/CO border. The front should be fairly
stationary once it is set up, so there could be a decent duration
to precip with snow levels dropping to around 7000ft behind the
cold front. Day 3 snow probs for >6" are 30-60% in the Wind River
and Bighorn ranges as well as around 50% on the Laramie Mtns and
20-40% on the Front Range in northern CO. Decently heavy mountain
snow then persists through Tuesday, so more info is to come on this
system.


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


Jackson