Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
336 AM EST Wed Nov 13 2019

Valid 12Z Wed Nov 13 2019 - 12Z Sat Nov 16 2019


...Great Lakes...

Day 1...
Low-level winds will begin to back to the S/SW ahead of a
shortwave/weak low moving across the Northern Plains and Upper
Midwest. This will create a WAA Lake Effect Snow (LES) setup, with
the heaviest snow likely along the long-fetch of Lake Michigan.
Lake water temperatures are still very warm, so despite WAA, the
deltaT is sufficient for modest instability across the Lakes which
will support snow band development. Soundings indicate intense
omega, some of which will overlap the lower portion of the
saturated DGZ, which could enhance SLRs above the modest SLRs
typical of WAA LES. Additionally, high-res guidance is indicating
subtle low-level fgen development this aftn/eve, mostly along the
eastern shore of Lake Michigan.

All of this together has caused an uptick in snowfall forecasts
for the area, and WPC probabilities indicate a high chance for 6
inches in the eastern U.P. of MI, with high probabilities for 4
inches along the extreme W/NW coast of the L.P. Isolated amounts
to 12 inches are likely where the band focuses before slowly
shifting eastward by the end of day 1.

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

Weiss