915
FOUS11 KWBC 201935
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
235 PM EST Thu Nov 20 2025

Valid 00Z Fri Nov 21 2025 - 00Z Mon Nov 24 2025

...Southern & Central Rockies...
Day 1...

An upper trough that is becoming negatively titled over New Mexico
today will weaken overnight as it shears out to the east after
00Z. Snow over northern AZ/NM into UT/CO, with relatively high snow
levels >8000ft, will still persist into early Friday as lingering
convergence and upslope muster up another inch or two of snow over
the CO/NM Rockies. WPC probabilities show low-to-moderate chances
(30-50%) for additional snowfall totals >4" in the San Juans, the
Sangre de Cristos, and central CO Rockies (generally above
10,000ft).

...California & Southern Rockies...
Days 1-3...

A Pacific upper low making its way south-southeastward through
northern CA today will become positioned of the southern CA coast
on Friday. As healthy PVA and upslope flow ensue down wind of the
upper low this afternoon, periods of snow will taper off over the
Trinity/Siskiyou mountains and the persist along the Sierra Nevada.
Snow levels will hover around 6000ft over the central/southern
Sierra this evening and slowly drop overnight. Across southern CA,
snow levels around 6500ft this afternoon will drop to around
6000ft tonight. The upper low will continue to plunge southward
Friday night and become located west of Baja California by
Saturday. With the upper low so far south of the region, the colder
temperatures aloft will be displaced south and diminished upslope
flow will reduce precipitation rates. This will make rain the
primary precipitation type across southern CA on Saturday (though
some snow may linger over the tallest peaks of the SoCal
mountains). The upper low will begin to push east on Sunday that
will deliver additional high elevation mountain snow to the San
Juans and Sangre De Cristo above 10,000ft.

WPC probabilities for >8" of snow are >50% above about 9000ft over
the Sierra. Across the San Gabriel and San Bernadino mountains,
with a longer duration of precipitation through Friday, a significant
heavy/wet snowfall is likely. WPC probabilities for >8" of snow
are >70% above 7000ft (around the elevation of Big Bear Lake).
Three-day totals may approach 24" above 9000ft. This could cause
locally significant travel disruptions over these higher
elevations, along with the potential for some tree damage and
infrastructure impacts given the heavy/wet consistency of the
snowfall. The WSSI does depict some Moderate to locally Major
Impacts in the San Gabriel and San Bernadino Mountains above
8,000ft. In the Southern Rockies, WPC probabilities show low-to-
moderate chances (30-50%) for snowfall totals >6" in the more
remote/higher ridge lines of the San Juans and Sangre De Cristo.


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


Mullinax




$$