Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
407 AM EST Sun Nov 9 2025

Valid 12Z Sun Nov 09 2025 - 12Z Wed Nov 12 2025

...Michigan to Interior Northeast...
Day 1...

Leading shortwave impulse/vort max over northern IN early this
morning will swing over the Interior Northeast through tonight.
Ongoing deformation zone snow banding north of the associated
surface low tracks over southern MI rest of this morning and the
Buffalo metro this afternoon. Snow rates increase up to 1"/hr
through this swath can be expected as frontogenesis overlaps the
DGZ per the 00Z HREF. WPC probabilities for >4" after 12Z are
20-30% in southeast MI and around 60% over the greater Buffalo
metro.
Warm air advection ahead of this deepening low brings a warm nose
through this evening over northern NY/New England. Light freezing
rain is expected in at least pockets from the Tug Hill through the
Adirondacks and north as well as the White Mtns of NH/ME. WPC
probabilities for >0.1" ice accretion are between 40-70% in
northern NY and closer to 30% for the White Mtns.


...Lake Effect/Enhanced Snow through Tuesday...
Rapidly developing southern lobe of expansive low shifts south over
Michigan today before pivoting east over KY/TN tonight. The
developed low deepens over the northern Mid-Atlantic Monday night
before lifting over New England Tuesday. This will be the first
major lake effect and Appalachian upslope snow event of the
season. This pivoting of the developing low over the Great Lakes
region prolongs the cold air advection flow and thus lake
effect/enhanced snow from Lake Superior through Monday with single
banding likely off Lake Michigan tonight/Monday with
Huron/Erie/Ontario LES late tonight through Tuesday. Favorable QPF
spreads through all the Great Lakes before easing off Lake Ontario
on Tuesday.
The cold airmass, headlined by 850mb temperatures between negative
10 and 12 degrees C over the warm Great Lakes (temperatures of +10
to +15C) will result in an impressive convective environment with
model soundings indicating steep lapse rates and deep mixing
heights to near or above 700mb. Given lake temp and 850mb air temp
delta Ts of 20 to 30C, the environment will be rather supportive
for lake effect/enhanced snow production and possible thundersnow.

North-northwest to northerly surface winds along with increasingly
unidirectional winds aloft will act on the instability and support
the development of a few prominent north-south lake effect snow
bands, particularly downwind of Lake Superior through Monday, Lake
Michigan tonight through Monday, Lakes Huron and Erie late tonight
through Monday night, and Lake Ontario Monday night/Tuesday.
Decent confidence in heavy banding spreading west into the Chicago
metro this evening before drifting back east through Monday
morning. Localized totals over 1 foot are possible (30-60%) in
northwest IN depending on how long the single Lake Michigan
snowband can remain in tact. In addition, Cold upslope
northwesterly flow and a moist fetch from Lake Michigan will also
cause upslope snow showers for the Central/Southern Appalachians
tonight through Monday night with Days 2-3 WPC probabilities for
>6" 40-70%. Days 1-2 snow WPC probabilities for >8" are 60-80% in
the Huron Mtns of the U.P. of MI, northwestern Indiana, the central
Appalachians/Alleghenies, and southern Appalachian crest. A
forecast of heavy snow is on tap for Monday over the western shore
of MI. Additional 10% Day 2 WPC probabilities for >8" exist along
the shoreline of Lake Erie from northeast OH into northwest PA and
far western NY.



Jackson