FOUS11 KWBC 110623
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
223 AM EDT Sat Apr 11 2026

Valid 12Z Sat Apr 11 2026 - 12Z Tue Apr 14 2026

...Sierra Nevada and Rockies... Days 1-3...

Light snow associated with a weakening upper trough moving east of
the northern Sierra will continue into the afternoon in advance of
a more potent upper low diving south from Alaska. This deeper low
will move into NorCal tonight before slowly opening into a longwave
positively-tilted trough Monday around Reno and continuing into
Utah by early Tuesday morning.

Despite the overall weakening of the upper low through the period,
the combination of modest moisture anomalies (>90th-95th
percentiles for PW/IVT), incoming height falls, mid- level
divergence, an incoming 120kt jet streak, and upslope enhancement
via favorable mid-level flow will yield moderate to locally heavy
snow for tonight into Sunday over the Sierra.

The heaviest snowfall over the Sierra will be just in advance of
the upper/sfc low tonight through Sunday. Snow will also expand
eastward and northeastward across the Great Basin via broad SW flow
and PVA in the mid-levels. Snow levels will continue to fall today
into Sunday from around 6000-7000ft to around/below 4500ft with
the core of the colder air aloft. Snow rates of 1-3"/hr are likely
in the Sierra, making for difficult travel across the passes (WSSI
Moderate to Major impacts).

WPC probabilities of at least 8 inches of snow are >50% above
about 4500-5000ft in the Sierra and for at least 18 inches of snow
are >50% above about 5500-6000ft. Total accumulations may exceed
2-4ft in the highest peaks with windy conditions as well.

For the Great Basin to the Rockies, light to locally modest snow
in association with the incoming system will spread across the
region Sunday and continue through Monday. WPC probabilities for at
least 8 inches of snow are >50% above about 8000ft over eastern
NV/OR into the central Idaho ranges and above 10,000-11,000ft into
the Wind River Range and the Uintas.

The probability of significant icing for days 1-3 across the CONUS
is less than 10 percent.

Fracasso

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