Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
250 AM EST Tue Nov 25 2025

Valid 12Z Tue Nov 25 2025 - 12Z Fri Nov 28 2025


...Significant winter storm to impact parts of the Northern Plains
and Upper Midwest/Great Lakes through Wednesday before lake effect
snow intensifies on Thanksgiving. Key Messages have been issued
for this storm...


...Northern Plains/Upper Midwest/Great Lakes...
Days 1-3...

Shortwave trough moving through the northern Plains this morning
will continue eastward today. The sharpening upper jet across the
US/Canada supports a strengthening area of low pressure that will
move from the Plains to the Upper Midwest and western Great Lakes
over the next couple of days. An inverted trough over ND will act
as a focus for modest snow this morning, then translate east-
southeastward today as the surface low deepens over southeastern
MN. Trend in recent guidance was to bring this swath of light to
moderate snow farther south than just 12hrs ago, down the I-94
corridor into the Twin Cities. As the mid- level shortwave starts
to then close off, a TROWAL should form on the western side of the
storm as warmer air wraps northward and westward around the low.
This could allow for >1"/hr snowfall rates along with gusty winds
over 30mph, causing some blowing/drifting snow and low visibility
at times. By tonight into early Wednesday, the low will lift toward
the U.P. with northeasterly flow off Lake Superior, aiding in
enhancing moisture into the region just north of the 850mb low
(eastern central MN into northern WI).

By Wednesday night into early Thursday, the system will reach its
peak intensity over Ontario and take the bulk of its snow with it.
However, northerly to northwesterly flow will transition the lake-
enhanced snow to lake effect snow over northern WI into the U.P.
where the 850-lake temperature difference will be >15C (-10 to
-14C at 850mb and a lake temperature around 5C). Lake effect snow
 will eventually break out across the rest of the Great Lakes by
 Thursday morning and continue through the day and into Friday
 morning. With 850mb temperatures < -10C and Lakes Erie/Ontario
 SSTs around +10C, intense lake bands will persist on WSW to W to
 WNW flow as the cyclone pulls farther away from the region. Single
 banded snow will drop southward and become more multi-banded
 downwind of Lake Erie but may retain a stronger single band off
 Lake Ontario. Multi-banded snow will persist across the Upper
 Great Lakes as well through early Friday.

For the synoptic event D1, WPC probabilities for at least 6 inches
of snow are >30% from southeastern ND and northeastern SD eastward
across much of central MN from the Twin Cities northward to the
Arrowhead. Higher probabilities >70% exist across central MN and
northern WI to the U.P. of Michigan. After the surface low passes
and the snow becomes driven by lake effect (mostly D2-3), WPC
probabilities for at least 12 inches of snow are >50% from near
Ironwood eastward across the northern portion of the U.P. near the
Huron Mountains. This region is also where major impacts due to
snow amounts are possible as three day snow totals could be in
excess of two feet. Over northwestern Lower Michigan, lake effect
snow could yield in excess of a foot of snow as well (probabilities
are >50% just east of Traverse City). Residents and visitors in
the Upper Midwest/Great Lakes are advised to check the latest
forecast before traveling this week.

Lake effect snow will pick up in earnest over western and northern
NYS on Thursday (Thanksgiving) and continue into Friday. WPC
probabilities for at least 8 inches of snow are >70% over
northeastern OH, northwestern PA, and western NY as well as the Tug
Hill Plateau downwind of Lake Ontario. Areas that see stronger
snow bands hold the longest may see totals in excess of 18 inches,
especially over northwestern PA where WPC probabilities are already
>50%.

...Pacific Northwest/Northern Rockies...
Days 1-3...

An active North Pacific jet will send in two systems into the
Pacific Northwest and northern Rockies over the next three days.
The first will be today as the upper jet dips south across
Washington and a cold front (with a leading warm front) move in
from the west/southwest. Another system will form west of 140W
tomorrow and travel along the lead stationary/moisture boundary
into Washington on Thursday. Snow levels will start low today with
colder air in place but then rise on Wednesday as milder air wins
out across the region. The second system will push into the Rockies
late Thurs/early Fri.

For D1, colder sheltered locations along/east of the Cascades may
see some freezing rain as moisture moves in from the west.
Otherwise, snow levels initially near 2000-4000ft (north to south)
along the Cascades will slowly rise over the northern WA Cascades
but rise much quicker over the southern WA/northern OR Cascades to
over 6000ft by early Wednesday. Thereafter, snow levels will rise
well above 5000-6000ft Thursday as the second system moves in. WPC
probabilities of at least 6 inches of snow D1 are >50% above about
3000-4000ft in the WA Cascades (which includes Stevens and
Snoqualmie Passes). For D2-3, WPC probabilities for at least 8
inches of snow are >50% above about 5000ft. Farther east, much of
northwestern MT above 6000ft or so across the Lewis and Flathead
Ranges show probabilities of at least 8 inches of snow above 50%.


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

Fracasso

...Winter Storm Key Messages are in effect. Please see current
 Key Messages below...

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