Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
304 AM EST Sun Jan 23 2022

Valid 12Z Sun Jan 23 2022 - 12Z Wed Jan 26 2022

...Upper Midwest/Great Lakes/Northeast...
Days 1-3...

Broad and expansive troughing over much of Canada and the
northeastern 1/3 of the CONUS will support fast flow on its south
side through the Great Lakes. A pair of clipper systems will be
the main players days 1-3 along with lake effect snow. Lead
clipper will move through the Midwest today with a couple/few
inches through Ohio into western Pennsylvania and local maximum
near 5-6 inches near the surface low track. Cold airmass supports
SLRs near 20:1 coupled with modest lift through the DGZ. WPC
probabilities for at least 4 inches was moderate across northern
Ohio day 1 (mostly this morning/early afternoon).  

The second clipper will move quickly across the Canadian border
later Day 1, tracking just north of its predecessor. A stripe of
1-3 inches is likely from Chicagoland eastward across the Midwest
into western NY/PA days 2-3. The clipper will then lift through
the Northeast where a few inches will be possible as well. Lake
effect will be fairly constant even as winds vary as the systems
pass through, but mostly maintain a northerly to westerly
component.

Combined totals over the next 3 days could exceed 6-8" across
northern Ohio and perhaps the Laurel Highlands in PA via upslope
enhancement. The best potential for localized 12 inch amounts will
be over northern Lower Michigan (and southward on the eastern
shore of Lake Michigan) and across the U.P., especially eastern
areas.


...Rockies...
Days 2-3...

Petite mid-level shortwave will track smartly on the west side of
the Rockies Mon-Tue and toward the TX Panhandle by early
Wednesday. Despite limited moisture, broad-scale lift in the left
front exit region of the upper jet and upslope enhancement will
squeeze out a few inches across the higher elevations and
north-facing slopes of central Montana into Wyoming on day 2. As
the system sinks southward, light snow is expected through the
Colorado Rockies into the Front Range and western Kansas on
easterly flow with surface high pressure over the Corn Belt into
day 3, perhaps as far south as the TX Panhandle by Tues night into
very early Wed. The greatest WPC probabilities for 4 inches are
across south-central Montana southward to the Park Range and
Sangre de Cristos in CO.


For days 1-3, the probability of significant icing is less than 10
percent.


Fracasso