Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
416 AM EDT Mon Oct 17 2022

Valid 12Z Mon Oct 17 2022 - 12Z Thu Oct 20 2022


Days 1-3...
...Great Lakes...
Ongoing lake effect event is expected to continue today across
portions of Upper Michigan and far northern Wisconsin, with
several more inches possible across parts of the U.P.  The latest
WPC PWPF indicates additional accumulations of 6 inches or more
are likely, with some potential for an additional foot or more
across the higher terrain of the west-central U.P.  As colder air
continues to spread east, rain changing to snow is expected across
northern Lower Michigan.  Probabilities for accumulations of 4
inches or more have come down, however accumulating snows still
appear likely across portions of interior northern Lower Michigan.
 Accumulating snows are also likely in the lee of Lake Erie
beginning tonight and continuing through Tuesday, with a few
inches expected on the Allegheny Plateau into the central
Appalachians. 

Probabilities for accumulating snows have increased southeast of
Lake Michigan.  The overnight guidance showed an increasing signal
for a heavy lake effect band supported by steepening lapse rates
and deep northerly to northwesterly flow along the lake.  While
warm boundary layer temperatures and expected to limit
accumulations near the lakeshore, accumulations of at least an
inch or two of heavy wet snow now appear more likely for portions
of Northern Indiana tonight.   

The potential for additional light accumulations is expected to
continue for portions of the region into midweek.  However, as low
level temperatures warm and the upper low begins to lift out to
the north, the threat for heavy snow accumulations is expected to
wane Tuesday and Wednesday.

The probability of significant icing is less than 10 percent.

Pereira