From Mike Powell@618:250/1 to All on Tue Nov 11 08:53:15 2025
FOUS11 KWBC 110851
QPFHSD
Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
351 AM EST Tue Nov 11 2025
Valid 12Z Tue Nov 11 2025 - 12Z Fri Nov 14 2025
...Lake effect snow continues in the Northeast into tonight, while
an Atmospheric River brings heavy snow for the Sierra Nevada
Thursday into Friday...
...Interior Northeast... Day 1...
Anomalously deep upper low over Upstate New York will lift
northeast over New England today. The Great Lake effect snow
machine shifts focus to the eastern Great Lakes in the wake of the
low as northwesterly flow backs southwesterly tonight. Ongoing LES
bands enriched by Lake Huron that are further enhanced by Lake Erie
will continue to shift into north-central PA and western NY
(especially on the Chautauqua Ridge) with banding southeast of Lake
Ontario between Syracuse and the Tug Hill. These areas have 40-80%
probs for >6" from 06Z today to 06Z Wednesday. The southwesterly
flow tonight allows lake enhanced snow into the Buffalo metro and
the Tug Hill where Day 1.5 snow probs for >6" are around 40% and
80% at the top of Tug Hill. Warm air advection on the southwesterly
flow aids lift, but the thermal profile becomes less supportive of
higher snow ratios. Continued westerly flow Wednesday should allow
higher elevation snows, but at reduced rates.
...Sierra Nevada... Day 3...
An Atmospheric River impacts California Thursday through Thursday
night ahead of a full-latitude trough that likely spins into a low
off the SoCal coast into this weekend. High moisture plume with PW
of 1.25" to 1.5" brings high snow levels around 9000ft for snow
onset on the Sierra Nevada early Thursday. However, height falls
through the day Thursday allow snow levels to fall to around 6000ft
by Thursday evening and 5000ft early Friday as rates fall off with
the plume pushing to the Baja. Heavy snow can be expected down the
length of the Sierra Nevada with Day 3 snow probabilities for >12"
50-80 percent above about 7000ft and categorical above 9000ft.
The probability of significant icing is less than 10 percent.