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FOUS11 KWBC 180904
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
404 AM EST Sun Jan 18 2026

Valid 12Z Sun Jan 18 2026 - 12Z Wed Jan 21 2026


...Great Lakes...
Days 1-3...

Shortwave trough passages around an anchored deep low over Hudson
Bay maintains cyclonic flow through the Great Lakes with rounds of
heavy lake effect snow through next weekend. The Great Lakes are=20
currently mostly ice free (total ice cover estimated at 14% on Jan=20
17), with surface water temperatures between 2-6C (warmer over=20
southern Lake Michigan and Lake Ontario).

A long wave trough shifts east of the Great Lakes this morning
while the next reinforcing trough swings east across the extent of
the Lakes this afternoon through Monday. NWly flow brings Day 1=20
PWPF for >6" around 50% to the western U.P. (particularly the=20
Porcupine Mtns) and the western shore of the L.P.=20

The flow shifts westerly for Monday shifting the LES focus to the=20
eastern U.P. northern L.P. and for the eastern Great Lakes for=20
Monday with westerly single banding bringing 50-80% probs for >6"=20
to ares south of Buffalo and on the Tug Hill through Watertown.=20

A brief lull in LES sweeps across the Lakes Tuesday, though
single-banding persists on the Eastern Great Lakes. In particular,
the Tug Hill should see notable Day 3 snow with 60% probs for >12".=20


...Southeast, Mid-Atlantic, Northeast...
Day 1...

Positively-tilted full-latitude trough over the Mid-South=20
swing to neutral today as it shifts over the Southeast. Moisture
plume ahead of the trough is mainly rain, but with surface low
pressure developing off the GA coast, the back side of the precip
should turn into moderate bands of snow, particularly from the FL
Panhandle through central GA and the central Carolinas. With these
cases, even with surface temperatures just above freezing, dynamic
cooling could easily bring snow to the surface and accumulate via=20
decent rates of 0.5-0.75"/hr per the 00Z HREF. Day 1 PWPF for >2"
is around 10% in south-central GA and 20% in north-central NC into
southeast VA.

Further up the coast, precipitation will expand northeastward in=20
the right entrance of the >160kt jet atop marginal to cold=20
temperatures (milder along/east of I-95 in the Mid-Atlantic) and
increasing lower to mid-level FGEN. Elongated baroclinic zone and=20
the offshore surface low that rapidly develops as it passes Cape
Hatteras this afternoon and just outside the 40/70 benchmark=20
this evening. The westward extent of the precip shield, where the
snow bands will be is still prominent in 00Z guidance along the
extend of the Mid-Atlantic coast this afternoon and much of New
England late this afternoon through this evening. 00Z HREF mean snow
rates exceed 0.5"/hr over the Delmarva and NJ early this evening
and Long Island/southern New England late this evening through
midnight. Day 1 PWPF for >2" are 40% and up from Philly through
eastern Maine with 50% and up for >4" from NYC through CT/MA/RI and
along the immediate Maine coast. The max for the Day 1 PWPF is from
Providence to Boston where >6" probs are around 60%.=20


...Northern Plains...
Day 1...

**Snow squalls and blizzard conditions likely across parts of the=20
 northern Plains today. Key Messages linked below***

The next arctic cold front surges south across the northern Plains
today, with scattered snow squalls mainly this morning from eastern
Montana through the western Dakotas into central Nebraska. The
broad wind field with this front should also trigger blowing snow,
which when combined with additional falling snow could create
blizzard conditions, particularly in the WFO FGF CWA (please see
weather.gov/fgf for more info there).=20

Lapse rates reach or exceed 6-7C/km for a brief period along the=20
front and SNSQ parameters rise above 4-5 between eastern MT and=20
central NE. These parameters combined with low-to-mid level FGEN=20
intersecting with a healthy 100mb wide DGZ should allow for=20
efficient snowfall rates within these showers and bands. Wind gusts
up to 60 mph are also possible with this system, adding to the=20
blowing snow potential.

Snow squalls are particularly dangerous for those traveling on
roadways, with extremely low visibilities and slippery conditions
developing rapidly. Be sure to slow down, turn on your lights, and
exit the highway if possible should you get caught in a snow
squall.


...Central High Plains...
Days 1-2...

Cold air surges over the High Plains/against the front ranges of=20
the Rockies today ahead of a reinforcing shortwave trough that
shifts south over the Rockies tonight through Monday. Right=20
entrance jet dynamics over the front will allow banded snow to=20
develop over central MT/WY this evening with stronger banding=20
overnight from northern CO terrain through western KS with snow
bands lingering Monday morning over southwest KS into western OK.=20
The WNWly orientation of these bands is parallel to the flow and=20
should allow for persistence of narrow bands of moderate to=20
locally heavy snow. Day 1 PWPF for >2" remain limited to 30% over=20
the CO Front Range and east of the Palmer Divide in CO/western KS.
CAMs generally struggled with these synoptically driven bands that
have a risk for high performance given the motion along
orientation, so there remains a threat for 4"+ in persistent=20
banding scenarios.

Jackson



...Winter Storm Key Messages are in effect. Please see current=20
 Key Messages below...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late=
stKeyMessage_2.png__;!!DZ3fjg!8mgHyoidHlr2hQD8QC6_PkFw3gcML7nZY0LgmJfp3PNA_=
50yuIFMLCOpfSkQNcKumw5V4v5BVTNpxp0ITTZIl5fYnzo$=20



$$

=3D =3D =3D
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