922
FOUS11 KWBC 052051
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
351 PM EST Wed Nov 5 2025

Valid 00Z Thu Nov 06 2025 - 00Z Sun Nov 09 2025

...Pacific Northwest through the Central Rockies...
Days 1-3...

At the start of the forecast period, a remnant atmospheric river
plume will continue to migrate inland, spreading precipitation into
the Northern and Central Rockies late tonight and Thursday. The
mild nature of the eastern Pacific airmass spilling into the West
will maintain high snow levels around 7000-8000 ft with this
initial round, above pass levels. By tomorrow afternoon, another
compact closed low is forecast to pivot around the offshore mean
trough and usher in another atmospheric river, albiet weaker. While
WAA associated with this activity will result in gradually rising
snow levels throughout Thursday, impactful mountain snowfall is
still expected across the higher mountain passes in the Northern
Washington Cascades Thursday night into Friday. Eventually, a
shortwave translating eastward will once again shift mountain
snowfall chances into the Northern and Central Rockies. WPC
probabilities on D1 and bleeding into D2 depict a high likelihood
of 12+ inches (75-90%) of snowfall in the peaks of the northern
Washington Cascades. As the activity shifts eastward, 60-90%
probabilities of exceeding 6 inches are noted in the higher
elevations of the Wyoming Tetons.

...Northern Plains and the Upper Midwest...
Day 3...

Emerging clipper system is forecast to eject across the Northern
Plains as the aforementioned Rockies shortwave phases with a
disturbance in the Canadian Prairies. By Saturday, modest
frontogenetic snowfall is expected to develop along the northwest
flank of the surface low center as it dives southeastward across
the Northern Plains and Upper Midwest. Overall accumulations should
be quite low with this event (WPC probabilities of 1" are around
50%), but locally hazardous travel conditions could materialize
owing to strong gradient winds on the periphery of the low and some
areas experiencing their first snow of the season.

...Northern New England and the Adirondacks...
Day 1...

Forecast reasoning remains unchanged as a rapidly intensifying
clipper-type low pressure will move progressively E/SE from
Ontario, across New England, and then out to sea south of the
Canadian Maritimes by Thursday afternoon. This low will spread
significant moisture eastward on robust low- level FGEN leading to
a pronounced TROWAL pivoting across Northern New England. The
accompanying WAA will help spread significant moisture into the
area, but the WAA will also drive snow levels up to 4000-5000 ft,
suggesting that except for the highest peaks of northwest Maine,
the pre-low precipitation will be all in the form of rain Wednesday
afternoon. However, as the low tracks towards the New England
coast, rapid CAA in its wake, aided by impressive isallobaric flow
into the deepening system and topographically- enhanced upslope
flow, will cool the column dramatically, reflected by snow levels
falling to 500-1000 ft by 12Z Thursday. This results in a period of
moderate to heavy snowfall in the higher terrain, with light snow
gradually spreading into the lower elevations of VT/NH/ME and
Upstate NY before the DGZ dries and precipitation dissipates
Thursday afternoon.

The heaviest snowfall is likely to unfold above 2000ft in the
Adirondacks and Whites, although some moderate accumulations are
also likely in the highest Greens. This is reflected by WPC
probabilities which still indicate a moderate risk (50-70% chance)
for more than 4 inches of snow, with locally as much 8 inches in
the highest Presidential Range peaks. Light accumulations of a
dusting or more are likely elsewhere from Lake Ontario through
central Maine, except across the Champlain Valley, resulting in the
first notable snow of the year in some of the lower elevations of
northern New England.


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


Asherman/Mullinax







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