Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
323 PM EST Tue Dec 01 2020

Valid 00Z Wed Dec 02 2020 - 00Z Sat Dec 05 2020

...Great Lakes...
A deep low centered over the Lower Great Lakes will continue to
lift north into Canada overnight.  Snows are expected to gradually
diminish in the lee of Lake Erie, but not before several more
inches are possible Tuesday evening and overnight across
northwestern Pennsylvania into western New York.  Meanwhile,
westerly flow developing across Lake Ontario will support
developing snow, with locally heavy amounts possible Tuesday night
into Wednesday across the Tug Hill region.

...Southern and Central Plains...
Led by the hi-res guidance, the trend in the 12Z models was toward
a colder solution, with measurable snow likely from southeastern
Colorado and the northwestern Panhandle region to central Oklahoma
and eastern Kansas.  Potentially significant snowfall (4+ inches)
is appearing more likely for portions of northwestern Oklahoma and
south-central Kansas.  This is expected to develop during the day
on Wednesday and continue into Wednesday night.  Low-to-mid level
frontogenesis on the west side of a developing low moving east
across Oklahoma/Kansas is expected to support banded precpitation
and potentially heavy snow centered across northwestern Oklahoma
into southern Kansas late Wednesday into early Thursday.  Forecast
confidence is limited by what is expected to be a sharp
deliniation between rain snow and model spread with respect to the
rain/snow line.  While WPC guidance followed a compromise between
the hi-res and warmer global guidance, signficant weighting was
given to the colder models.

For Days 1-3, the probability of significant icing (0.25-inch or
greater) is less than 10 percent.

Pereira