Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
401 PM EST Mon Nov 17 2025

Valid 00Z Tue Nov 18 2025 - 00Z Fri Nov 21 2025


...Southern Minnesota into Central Wisconsin...
Day 1...

Mid-level low pressure over the Nebraska Panhandle this afternoon
shifts east to Iowa tonight and to northern Indiana Tuesday.
Dynamics with this system are sufficient to create locally heavy
deformation zone bands wrapping around the north side with enough
dynamic cooling to overcome the marginal thermal environment and
cause snow accumulations overnight through Tuesday morning. This
would be in a narrow stripe over southern MN (south of the Twin
Cities) into central WI. Day 1 WPC snow probs for >2" are 40-70%
through this zone which is a notable bump up from previous
forecasts. WFOs along this stripe have issued winter weather
advisories for this dynamic snow banding.


...California through the Southern Rockies...
Days 1-3...

A potent low pressure system currently approaching the San
Francisco Bay area will continue shifting down the CA coast tonight
before stalling off the SoCal coast through Tuesday night. This low
drifts inland Wednesday ahead of the next trough that approaches
northern CA Wednesday night.

Broad southerly flow wrapping around this low will pump subtropical
Pacific moisture northward and shift the focus of heavy snowfall
east of the crest of the southern Sierra Nevada and over the White
Mtns. Snow levels drop to around 7000ft under modest height falls
with moderate rates continuing through Tuesday. Day 1 snow probs
for >12" are 50-90% for the White Mtns and 40-70% for the higher
eastern
slopes of the Sierra Nevada west of Owens Valley.

The moisture plume expands east Tuesday, spreading high level snow
through Mt Charleston above Las Vegas and southern Utah ranges.
Day 1.5 snow probs for >8" are 50-80% above the snow levels
which linger around 8000ft into Wednesday before rates taper off.

The slow progression east of the moisture plume continues
Wednesday night when the Mogollon Rim, White Mtns of AZ get heavy
snow as snow levels drop to around 7000ft as do the San Juans of CO
where snow levels drop to around 8000ft. Day 3 snow probs for >8"
are 40-80% in this terrain.


...Northeast/Great Lakes...
Day 1...

West-northwesterly flow lingers over the eastern Great Lakes and
drives continued LES banding into Tuesday. This will continue to be
southeast of Lake Erie (where there is also Lake Huron fetch) from
the Chautauqua Ridge into north-central PA and generally just south
of Syracuse where a winter weather advisory lingers to mid-Tuesday
morning. Day 1 snow probs for >4" are limited to around/south of
Syracuse, though the low resolution ensemble member heavy PWPF
often under does the risk for LES banding.



Jackson