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FOUS11 KWBC 141935
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
235 PM EST Wed Jan 14 2026

Valid 00Z Thu Jan 15 2026 - 00Z Sun Jan 18 2026


...Upper Midwest through Northeast, and the Appalachians...
Days 1-3...

The longwave trough in place across the eastern CONUS will
repeatedly reload into the weekend, becoming increasingly amplified
as shortwaves periodically drop south out of Canada and rotate
through the trough and then off the east coast. The core of this
trough will deepen most impressively over the Gulf Coast Thursday
aftn (ECMWF 500mb heights as low as the 0.5 climatological
percentile). Within this progressive flow, even as these lead
impulses rotate away on Friday, the next shortwave trough will
follow immediately in its wake, moving from the Northern Plains to
the Mid-Mississippi Valley Friday night. Similar to the Southeast
on Thursday afternoon, 500mb heights over the Missouri River Valley
are likely to be as low as the 0.5 climatological percentile.

In addition to producing true winter cold air across much of the
eastern 1/3 of the CONUS, and potentially some of the coldest wind
chills of the season, widespread snow is likely from the Upper
Midwest through the Tennessee Valley and back northeast through the
Central Appalachians and into the Northeast. While most of this
snow will be more "conversational" and light than impactful, there
are a few areas that will experience more significant snowfall.

Great Lakes: Periods of lake effect snow (LES) are likely each day
as persistent cyclonic flow and periodic shortwaves/fronts renew
CAA across the lakes. The heaviest LES is likely D1, especially
downwind of Lake Michigan into northern Indiana where, despite some
modest longitudinal fluctuations in the axis from the most recent
model runs, a long fetch north-south across Lake Michigan should
result in a narrow and intense single band of snow into far SW MI
and northern IN. Here, HREF probabilities for 1+"/hr snowfall peaks
above 60% for much of D1, and with locally 2-3"/hr snowfall rates
possible, WPC probabilities support a high risk (>70%) for more
than 12", and locally up to 20 inches is possible. Elsewhere, heavy
snowfall is likely south of Lake Erie along the Chautauqua Ridge
where WPC probabilities indicate a moderate risk (30-50%) for more
than 12 inches. Otherwise, while LES will be periodic and briefly
intense at times all 3 days, additional snowfall in other areas
should generally be around 6 inches or less, especially southeast
of Lake Ontario and across portions of the U.P. of MI.

Central Appalachians: The passage of an arctic front associated
with the lead shortwave will quickly cool the column to change
precipitation from rain to snow, with post-frontal gusty westerly
winds leading to pronounced upslope flow. Regional soundings
suggest favorable ascent into steepening lapse rates and elevated
low-level moisture to support heavy snow rates from the higher
elevations of NC near the Smoky Mountains northward through the
Central Appalachians of WV and into the Laurel Highlands. Guidance
has trended a little wetter and more intense with this event, and
WPC probabilities now reflect a high chance (>70%) for more than 6
inches in the higher terrain, generally above 3000 ft, across this
region on D1. Light snow showers will likely continue, although
with minimal additional accumulations on D2, but renewed upslope
flow with a secondary front D3 could again result in a few inches
of snow (WPC probabilities above 30% for 4+ inches) across the
higher elevations from NC to WV once again.

Interior Northeast: A surface low pressure moving across PA tonight
will continue to push northeast, reaching Atlantic Canada by
Friday morning. This low will be accompanied by modest warm/moist
advection to spread precipitation across Upstate New York and
northern New England. While the guidance has trended north to focus
the heaviest snowfall across Canada, a modest TROWAL pivoting
westward behind this low and interacting with an inverted surface
trough elongated from the primary low will pivot some heavier
snowfall tonight through Thursday aftn. Brief snowfall rates in
excess of 1"/hr are possible (10-30%) across the Adirondacks,
northern VT, and near Lake Ontario tonight before lifting northeast
through Thursday. As the low pulls away, some upslope snow on
increasing NW winds may also lead to heavier rates across the
Adirondacks and Greens. WPC probabilities across this area are
moderate (30-70%) for 8+ inches of snow through Friday, with the
greatest accumulations likely near the St. Lawrence Valley, the
Adirondacks, and the northern Greens.


...Northern/Central Plains...
Day 2...

A potent shortwave and accompanying vorticity lobe will drop
rapidly southward out of Saskatchewan/Manitoba into the Dakotas and
then continue to dig southeast reaching the Mid-Mississippi Valley
by 00Z Saturday /end of D2/. This feature will drive an arctic cold
front southward, and the overlap of modest, but transient, height
falls, PVA, and low-level convergence along the front will
manifest as periods of snow showers, with coverage and snowfall
amounts limited by below-normal PWs and ongoing CAA. However,
impressively strong winds within the PBL and exceptionally steep
low-level lapse rates will encourage any snow showers to be
accompanied by gusty winds, and where low-level fgen combines with
modest 0-2km CAPE of 100-200 J/kg, convective snow showers may
result. While the duration and coverage of these may be limited, as
reflected by most simulated reflectivity, any of these snow
showers will likely include limited visibility and brief heavy snow
rates. This could produce hazardous travel as reflected by 30-50%
chance for moderate impacts from the WSSI-P despite snowfall
amounts that will likely (>70% chance) be less than 2 inches from
the Dakotas into western Minnesota and down into Nebraska/Iowa.


The probability for significant ice across the CONUS is less than
10%.


Weiss


$$

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