FOUS11 KWBC 250734
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
334 AM EDT Sat Apr 25 2026

Valid 12Z Sat Apr 25 2026 - 12Z Tue Apr 28 2026

...Western U.S Overview...

A 500mb shortwave trough rotating around the southern flank of a
500mb low off the CA coast today will track across central
California Saturday night and reach the central Rockies by late
Sunday. Healthy PVA over the Rockies and the left-exit region of a
250mb jet streak positioned overhead will foster excellent upper-
level divergence while a healthy slug of 700-300mb moisture arrives
from the subtropical Pacific. Temperatures aloft are not overly
cold, so snowfall will be confined to the higher elevations of the
Sierra Nevada on east across the Intermountain West. Meanwhile, a
secondary trough over the Pacific Northwest will generate the same
favorable divergence aloft on Sunday. This trough will become more
sheared Sunday night into Monday, but it will contribute to the
longwave trough entrenched over the West. These features will work
together to bring beneficial snowfall to the Rockies this weekend
and into Monday.

...Sierra Nevada... Days 1-2...

Snowfall begins in the central/southern Sierra Nevada ahead of
this shortwave trough Saturday afternoon. Snow levels initially
around 7,500ft drop to around 6,000ft tonight before precip tapers
off. Some minor snowfall may linger on Sunday, but at the more
remote elevations above 9,000ft. Saturday and Sunday snow probs for
>4" are >50% in the higher elevations of the Sierra Nevada south
of Sonora Pass and the White Mtns.

...Great Basin, central/southern Rockies, & the Black Hills... Days 2-3...

Precipitation quickly expands east from central NV and into the CO
Rockies Saturday night lingering through Sunday. Snow levels
linger around 8000ft in NV/UT while 9,000ft snow levels in CO drop
to 8,000ft Sunday evening. The aforementioned secondary trough
axis delivers more light precip to UT/CO, while also expanding the
precipitation shield farther north across western WY and the
southern MT Rockies on Sunday. The presence of the longwave trough
over the West will keep periods of lighto-to-moderate mountain snow
in the forecast through Monday. Days 2-3 snow probs for >4" are
high (>70%) for just about all of the mountain ranges referenced,
with the more remote reaches of the Uinta and CO Rockies having at
least 50% chances for over a foot of snowfall. Accumulating snow is
likely as far east as the Black Hills, where WPC probabilities
sport low-to-moderate chances (20-40%) for >4" of snowfall.

While some locally hazardous travel over nearby passes are
possible, snowfall throughout the Central Rockies will be more
beneficial than harmful, on account of the below average snowpack
throughout the region.

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

Mullinax
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