FOUS11 KWBC 281952
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
252 PM EST Sun Dec 28 2025

Valid 00Z Mon Dec 29 2025 - 00Z Thu Jan 01 2026

*** Major Winter Storm for the Upper Midwest/Great Lakes and
Northeast into Monday ***

...Great Lakes/Northeast...
Days 1-3... Maximum impact level from WSSI: Major to locally
Extreme

There are no shortage of weather-related hazards for this impending
major winter storm. Below is a break down of these hazards over the
next 1-2 days.

--Snow and Wind--

The deepening upper-level low over the Midwest this afternoon will
work in tandem with a coupling 250mb jet streak structure to
support a rapidly deepening surface low that will track from
northern Illinois through lower Michigan tonight. Anomalous PWATs
ahead of the upper low will wrap around the northern and western
flanks of the storm's 700mb low, causing heavy snow to ensue just
north of the best 850-700mb FGEN from northern WI on east through
the U.P. of MI. In addition, moderate-to-heavy snow breaks out
beneath the TROWAL over most of MN and into WI this afternoon and
into tonight. WPC's Snowband Probability Tracker shows 1-2"/hr
snowfall rates (locally up to 3"/hr possible) in the FGEN banding
over northern WI and the MI U.P. this evening and into early Monday
morning. If heavy snow was not concerning enough, high winds will
accompany this storm thanks to this storm deepening into the 970s
over the Great Lakes Monday morning and strong high pressure over
the northern High Plains causing a very tight pressure gradient.
Wind gusts up to 50 mph are likely in parts of the Upper Midwest
and Upper Great Lakes this evening with gusts topping 60 mph
possible along the northern shores of MI's U.P and western shores
of MI's Lower Peninsula. The aforementioned TROWAL pivots over the
Great Lakes early Monday morning with bursts of heavy snow possible
as far south as Chicagoland and southern MI with lingering bands
of lake-effect snow over western MI and the Michigan U.P..

WPC probabilities show high chances (>80%) for snowfall totals

12" from northwest WI throughout most of MI's U.P.. Given the

longevity of the snow in the MI U.P. through Monday evening (thanks
to LES bands) WPC probabilities show moderate to high chances
(40-70%) for localized totals topping 24" for much of the central
U.P. and even 30% for >30" and just west of Marquette. Farther
west, WPC probabilities show moderate- to- high chances (50-70%)
for snowfall totals >6" around the Twin Cities metro area on east
into western WI. Snowfall totals are forecast to range between 2-4"
along the ND/SD/MN borders and as far south as northern IA, but
those totals paired with high wind gusts will likely bring
blizzard conditions this afternoon into tonight. Travel will be
dangerous to impossible in northern WI and the MI U.P. through
Monday. Expect treacherous travel due to whiteout/blizzard
conditions in portions of the Midwest this afternoon and through
Monday morning due to heavy snow and whipping wind gusts topping 50 mph.

--Hazardous Ice--

A heavy wintry mix begins the storm for the eastern U.P. and MI's
Mitten through this evening before transitioning to heavy snow
overnight. The boundary layer across much of the Northeast remains
cold enough at the onset; via both cold/dry wet-bulb temperatures
courtesy of a departing Canadian high to the north, or event
lingering snow pack from Friday night's winter storm, to allow for
freezing rain to efficiently accumulate on all surfaces starting
this afternoon from northern PA and northern NJ on north to the
Catskills and Finger Lakes, then into the the Hudson Valley,
Adirondacks and on north into northern New England this evening and
into Monday morning. The heaviest icing is most likely to occur in
the Adirondacks, Green, and White Mountains where despite the
strengthening WAA aloft, low- level cold will be harder to scour
out as sub-freezing temperatures lay trapped in the valleys of
these regions.

WPC probabilities show high chances (>70%) for ice accumulations

0.25" in these mountain ranges with low chances (10-30%) for

localized ice accumulations surpassing 0.5". As much as a tenth of
an inch of ice is forecast from northern PA this afternoon through
the Poconos, Catskills, Lower Hudson Valley, the St. Lawrence
River Valley, through northern CT and central MA, southern NH, and
into much of ME. Roads throughout the interior Northeast will be
treacherous with lingering ice likely to impact the Monday morning
commute. In areas where ice accumulations top 0.25", wind gusts
above 30 mph could cause added stress on trees and power lines,
leading to instances of tree damage and power outages for the
interior Northeast.

--Additional Snowfall Monday night and into mid-week--

As the surface low heads north and east into Quebec Monday
afternoon, cyclonic flow and strong CAA in wake of the cold
frontal passage will keep LES bands and widespread snow showers in
the forecast over the (westerly wind) snow belts downwind of Lakes
Erie and Ontario. Plus, NWrly winds will support upslope snowfall
from as far north as the Adirondacks, Tug Hill, and Green mountains
to as far south as the Laurel and Potomac Highlands of southern
PA, western MD, and eastern WV into Monday night. It is worth
noting there is also evidence on 12Z CAMs, via steep low- level
lapse rates along a secondary cold front, that snow squalls could
race east across eastern OH, much of PA, and Upstate NY Monday
afternoon and evening.

This is quickly followed by a clipper system that will traverse
the Great Lakes from the northwest on Tuesday/Tuesday night,
ushering in a round of light to moderate snow over the Great
Lakes. The LES machine picks up again over the MU U.P., the Tip of
MI's Mitten, and downwind of Lakes Erie and Ontario into
Wednesday before yet another clipper late Wednesday.

...Southeast New Mexico/Guadalupe Mountains...
Day 2... Maximum impact level from WSSI: Moderate

A cold front racing south through the High Plains ushers in strong
low-level CAA amidst ENErly flow tonight. This results in
topographic enhancement on the Guadalupe and southern Sacramento
Mountains that will play a key role in cooling the boundary layer
to support snow into Monday. Meanwhile, there are also sufficient
synoptic and mesoscale factors to support heavy snow in the
Sacramento and Guadalupe Mountains. Sunday night and into Monday,
the region will be positioned beneath the divergent right-entrance
region of a 250mb jet streak. Over the Southwest U.S., a positively
tilted 500-200mb trough axis stretches as far south and west as
the tropical East Pacific. Guidance is in agreement on a healthy
plume of anomalous 700-300mb moisture that leads to PWATs that top
0.6", or above the 97.5 climatological percentile per ECMWF
guidance. Lastly, the 700mb WAA via SWrly flow over southern NM and
west TX runs into northerly 700mb winds over High Plains that
causes a band of 700mb FGEN aloft.

HREF guidance is highlighting potentially 1"/hr snowfall rates
over the Sacramento and Guadalupe mountains between 09Z and 22Z
Monday. Given how warm it has been of late in the Southwest, it
will take some hours of moderate-to-heavy snow to cool most
surfaces to the point where accumulation can steadily occur. WPC
probabilities continue to highlight moderate chances (40-60%) for
snowfall totals >4" in these mountain ranges. Localized snowfall
totals topping 8" are possible in the highest elevations. To the
east, light snow of a couple inches is possible to the TX border
where WPC probabilities of at least 2 inches are 20-50%. Notable US
roadways that could witness delays due to measurable snowfall are
US-285 between Roswell and Carlsbad, then south and west along
US-62/180 that cuts through Guadalupe Mountains N.P..

Mullinax/Jackson

...Winter Storm Key Messages are in effect and linked below...

https://www.wpc.ncep.noaa.gov/key_messages/LatestKeyMessage_1.png

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