Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
412 AM EST Fri Nov 08 2019

Valid 12Z Fri Nov 08 2019 - 12Z Mon Nov 11 2019


Days 1-3...

...Great Lakes...
Northwest flow/cold air advection will continue to support lake
effect snow showers today, and again more impressively on Sunday
/Day 3/. While WPC probabilities for 4 inches are minimal on day
1, and focused in the eastern portions of the U.P. and NW L.P. of
MI, probabilities increase on day 3, especially for the U.P. N to
NW flow increases, and mixing depths deepen with a saturated DGZ
Sunday, and there is likely to be a prolonged period of LES
potential in the favored NW snow bands off of Superior and
Michigan Sunday.

...Northern Rockies/High Plains...

A surface cold front will drop from Canada into the Central Plains
Saturday and Sunday, plunging anomalously cold air southward.
Strong frontogenesis and robust ascent within the diffluent region
of a potent upper jet streak will combine to produce a swath of
snowfall from Montana through Nebraska. The heaviest snowfall is
likely in the terrain of MT and into the Black Hills of SD where
low-level upslope flow will enhance ascent, and WPC probabilities
are 20-50% for 6 inches. Elsewhere, lighter snows are likely from
the Canada/CONUS border southeast through the High Plains of CO
and Nebraska.  

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

Weiss