006
FOUS11 KWBC 191858
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
158 PM EST Wed Nov 19 2025

Valid 00Z Thu Nov 20 2025 - 00Z Sun Nov 23 2025

...Southern & Central Rockies...
Days 1-2...

An upper low tracking through the Desert Southwest today will
sharpen up and take on an increasingly negative tilt over northern
Mexico tonight and into Thursday morning. Healthy 500mb PVA and an
influx of moisture (courtesy of IVT values topping 400 kg/m/s that
exceed the 97.5 climatological percentile per ECMWF SATs) will
be the key ingredients in a blossoming area of precipitation over
AZ, NM, southern UT, and southern CO. Temperatures aloft are not
overly cold and the antecedent air-mass is generally mild, thus
forcing most of the impending snowfall to occur in the more
remote/higher terrain of the Southern Rockies.

As the upper trough reaches the Southern Plains Thursday night,
the 500mb trough will become inverted with a narrow tongue of
easterly upslope flow still producing a persistent light-to-
moderate snow in the forecast into Friday morning. Snow levels for
the event may dip as low as 6,000ft in parts of the Wasatch and as
far south and west as Zion Nat`l Park, but the bulk of the more
impactful snowfall totals will reside above 7,000ft in the
mountains surrounding Las Vegas and the southern Wasatch, above
8,000ft in the Mogollon Rim and Gila Mountains of AZ, above
9,000ft in the San Juans and Sangre De Cristo, and above 10,000ft
along the CO Front Range. WPC probabilities show most of these
ranges above the listed elevations are likely to see at least 4"
of snowfall, but it will be in these mountains` more
remote/elevated reaches that sport low-to-moderate chances
(30-50%) for snowfall totals >8" through Friday.

...California...
Days 1-3...

As this lead upper-trough tracks towards the South-Central U.S. on
Thursday, the next Pacific upper-level trough is hot on its heels
as it dives southward along the CA coast. A progressive system, it
will produce a swath of accumulating snowfall at/above 5,000ft
from the Trinity/Siskiyou mountains of northern CA on south along
the Sierra Nevada and even the peaks of the Transverse and
Peninsular ranges. The heaviest snowfall for the Sierra Nevada is
expected on Thursday with snowfall tapering off by Friday morning.
WPC probabilities depict moderate-to-high chances probabilities
(50-8%) for snowfall totals >6" in the central and southern Sierra
Nevada with localized totals approaching 12" in the >10,000ft
peaks.

Snow will pick up in intensity over the peaks of the San Gabriel
and San Bernadino mountains starting Thursday afternoon and lasting
through Friday morning. Snow should taper off in the peaks of the
Transverse and Peninsular ranges by Saturday morning. Snow levels
are likely to be as low as 6,000ft with minor accumulations
possible around that elevation, but the heaviest snowfall is likely
to occur above 7,000ft where WPC probabilities show moderate-to-
high chances (50-80%) for snowfall totals >6" and even low-to-
moderate chances (30-50%) for localized amounts >12" in the peaks
of the San Bernadino mountains.


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


Mullinax




$$