Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
342 AM EST Mon Jan 10 2022

Valid 12Z Mon Jan 10 2022 - 12Z Thu Jan 13 2022

...Great Lakes...
Days 1 and 3...

Strong cold air advection under an upper trough with a reinforcing
trough tracking north of the Great Lakes today will result in
about 18 hrs of intense lake effect snowfall on WNWly flow over
Lake Ontario (with stream lines tracing back through Lakes Huron
and Superior) roughly between Syracuse and the center of the Tug
Hill Plateau where favorable ascent into the DGZ combined with
impressive instability nearing 1000 J/kg and aided by orographics
on the north side will produce 1-2"/hr snowfall rates in a single,
slightly wavering band, per the 00Z HREF with 12-18" likely across
this area with local amounts of 2'. Downwind of Lake Erie,
generally south of Buffalo, and in the eastern U.P. of MI, WPC
probabilities are low for 6" with multi-bands setting up. Flow
backs toward northerly tonight as a high pressure center shifts
east across the Lakes. LES off Erie and Ontario dissipate by 15Z
Tuesday.

The next cold front into the Great Lakes is forecast to enter Lake
Superior late Tuesday night and cross at least northern sections
of the Lakes Wednesday. As of now the best chances for heavy snow
are once again of the east side of Lake Ontario into the Tug Hill.


...Pacific Northwest...
Days 1-3...

A series of shortwave troughs/impulses today through Tuesday and
the approach of a deeper wave Wednesday night makes for continued
active weather across WA and into the northern Rockies and
northern OR. Nearly continuous mountain snow is expected with snow
levels rising from around 4000ft this morning to over 6000ft
tonight through Wednesday night. The greatest moisture surge is
Tuesday with a few feet of high terrain snow likely. Periodic low
level light precip onto the Columbia Gorge and Columbia Basin
where low-level cold air is entrenched will allow light freezing
rain accumulations, likely near the Gorge today and over the Basin
for Days 2/3.

Jackson