FOUS11 KWBC 280847
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
347 AM EST Thu Nov 28 2024

Valid 12Z Thu Nov 28 2024 - 12Z Sun Dec 01 2024

...New York/Northern New England...=20
Day 1...

*** Powerful Nor'easter in the Northeast through this evening ***

Low pressure rapidly developing over the south-central Appalachians
will track northeast to the New England coast today before lifting=20
into the Canadian Maritimes tonight. Front-end and=20
deformation/TROWAL banding will allow heavy snow bands to pivot=20
over areas from northern PA through eastern NY and northern New=20
England. Intensity increases today with snowfall rates exceeding=20
1"/hr (per 00Z HREF) expected in banding from the Catskills to the=20
Adirondacks (including the Mohawk Valley in between) by later this=20
morning expanding over the Greens and Whites of VT/NH into interior
Maine this afternoon. Rates of 2"/hr should be limited to the=20
higher terrain, but multiple hours of heavy snow accumulation can=20
be expected in a cooling environment that overcomes diurnal trends=20
to affect valleys and ridges alike. These bands spread over much of
interior Maine this evening and persist into the overnight before=20
lifting north of Maine before daybreak Friday.

Day 1 PWPF for >6" are 40-80% for a swath from the Catskills
through northern Maine (with an gap over much of the Hudson Valley)
and over a foot is likely in the highest terrain and portions of=20
interior Maine. WSSI is only moderate for these areas for both snow
amount and load. However, given the propensity for banded snow
ahead and around the north side of rapidly developing lows to
overachieve, great caution should be taken with travel in this=20
swath, particularly over terrain.



..Great Lakes...
Days 2-3...

*** Heavy Lake Effect Snow event tonight through Monday ***

A mid-level low will remain stalled near James Bay into Saturday=20
as a succession of shortwave troughs/vort lobes crosses the Great
Lakes. Reinforcing troughs then push over the eastern CONUS into
Tuesday, prolonging a potent LES case. Surges of cold air over the
still warm lakes will result in heavy LES with persistent NWly flow
over the upper Lakes and WNWly to Wly flow over the eastern/lower=20
Lakes.

Multi-bands can be expected off Superior/Michigan and with single
bands developing over Erie/Ontario tonight. Heavy LES with rates=20
that will likely eclipse 2"/hr at times. Expect 2-4 feet of snow=20
through Saturday night in the most long-lasting and intense bands=20
over favored portions of the southern Superior shore, along much of
the eastern Erie shore south of Buffalo, and just north of the Tug
Hill/near Watertown, NY. Flow looks to veer to NWly on Sunday,=20
pushing the bands over Erie/Ontario farther south and bringing
relief to areas experiencing the worst of this case.

The arctic-sourced cold and LES off the Great Lakes through the=20
weekend is the subject of the Key Messages which are linked below.=20


...Central Plains to Mid-Mississippi Valley...
Day 3...

Clipper will amplify over the central Plains Friday night and bring
banded snow to the lower Missouri Valley Saturday, southern=20
IL/much of KY Saturday night, and southern WV Sunday. Decent
baroclinicity and cold profiles with some saturation in the DGZ
should result in moderate to potentially briefly heavy rates of
fluffy snow. Day 3 PWPF for >2" is around 20% in north-central
portions of MO and over southern WV. Given the banding potential
greater snow totals are possible, so stay tuned for updates.


The probability of significant ice across the CONUS is less than
10 percent.=20


Jackson



...Winter Storm Key Messages are in effect for the Northern Plains
and Great Lakes...

https://urldefense.com/v3/__https://www.wpc.ncep.noaa.gov/key_messages/Late=
stKeyMessage_1.png__;!!DZ3fjg!_NcTtyASwFF4Fd7CKMQ1lysqrKRxrAMC7_5MC8ySY0m80=
Pf8tEUi89lXfppGldK2lB05OZnVJytliriZ3VoIsQUj-_0$=20

$$

=3D =3D =3D
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