Subj : HVYSNOW: Probabilistic He
To   : All
From : Mike Powell
Date : Wed Jan 14 2026 09:30:58

FOUS11 KWBC 140751
QPFHSD

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

Valid 12Z Wed Jan 14 2026 - 12Z Sat Jan 17 2026

....Northern Plains through the Northeast, and the Appalachians... Days 1-3...

A longwave trough across the eastern CONUS will amplify and
periodically re-load through the upcoming weekend as repeated
shortwaves intensify and drop southeast from Canada. 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.

The headlining weather hazard, aside from some of the coldest
temperatures and wind chills of the season-to-date, will be the
multiple days of lake effect snow (LES) downwind of the Great
Lakes, especially in the more northerly belts as winds become NNW
beneath strong CAA. WPC probabilities for LES are high (>70%) for
more than 8 inches in the higher elevations of the U.P. including
the Huron and Porcupine Mountains, as well as along the E/SE shore
of Lake Michigan into northern Indiana. Lake-enhanced snowfall
will also unfold along the Chautauqua Ridge and Tug Hill through
Thursday. There are likely to be some localized totals over 12
inches along the Chautauqua Ridge, along the shores of Lake
Ontario, and on the Tug Hill. The heaviest LES is likely in a
single band off Lake Michigan into SW MI/NW IN late Wednesday
through late Thursday. CAMs guidance is showing steep lapse rates
and exceptional vertical velocities that coincide within a fully
saturated DGZ-- a clear sign of a robust LES band. WPC
probabilities show moderate chances (40-60%) for snowfall totals
>12 inches where localized amounts approaching 20" cannot be ruled
out given the potential for prolific >2"/hr snowfall rates beneath
a band that will oscillate between southwest MI and northwest IN
for a 12-24 hour stretch.

Across the Central Appalachians and Northeast, the lead shortwave
will not only work together with an Atlantic-offshore jet streak to
create low pressure development across the Northeast, but also drag
an arctic front from the Ohio Valley through the Mid-Atlantic on
Thursday. This will create a short period of heavy upslope snow
from the higher elevations of NC through the Laurel Highlands of PA
where WPC probabilities are moderate (50-70%) for at least 4
inches, generally above 3000 ft, with locally 6-8 inches possible.
The tallest peaks of the Smokey Mountains could see localized
totals approach 12 inches. Farther north into Upstate NY and
northern New England, model guidance has trended snowier over the
past 12-24 hours of model cycles as the slightly longer duration
of moderate-to-heavy snowfall just north and west of the 850mb low
appears to be coming to fruition. The deformation zone will
maintain a saturated profile long enough, within an atmosphere that
supports rising SLRs, to produce heavy snowfall beginning as early
as Wednesday afternoon and continuing into Thursday. WPC
probabilities show moderate-to-high chances (50-70%) for snowfall
totals >8 inches from northwest PA through much of western NY and
into NY's North Country and St. Lawrence Valley.

Finally, on D3 with the next shortwave digging out of Saskatchewan
into the Upper Midwest, height falls and modest warm/moist
advection will create a swath of generally light snow, followed by
strong winds behind yet another arctic front. WPC probabilities
indicate only a 10-30% chance for at least 4 inches of snow for
parts of SD/MN/WI, but WSSI-P suggests an increasing threat for
blowing snow impacts just behind this wave, so travelers should be
prepared for hazardous driving Friday despite the modest snowfall
amounts forecast. Farther east, the shortwave trough will once
again kick-up LES bands across the U.P. and western shores of
Michigan. WPC probabilities show high chances (>70%) for snowfall
totals >4 inches in the U.P.'s Porcupine Mountains and moderate
chances (40-60%) for >4 inches of snow over the western MI shore.
The Porcupines have the best odds at locally heavy totals with
low-to-moderate chances of totals >8 inches.

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

Mullinax/Weiss
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