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

Valid 00Z Sat Nov 09 2019 - 00Z Tue Nov 12 2019


Day 1...

The probability of heavy snow and/or significant icing (0.25-inch)
is less than 10 percent.

Days 2-3...

...Northern Plains and Rockies...
Models are in good agreement showing a low-amplitude shortwave
dropping southeast across the northern Plains on Saturday -
producing a stripe of light rain changing to mixed precipitation
across North Dakota into central Minnesota. 

An amplifying shortwave digging south across western Canada will
push an arctic cold front southwest through the northern Plains
and Rockies.  Post-frontal upslope flow along with low-to-mid
level frontogenesis and some modest upper jet forcing is expected
to support light to moderate snows developing and spreading
southeast from Montana into the western Dakotas Saturday night
into early Sunday.  Snow is forecast to shift south and east
across the region through Sunday before diminishing Sunday night. 
This is expected to produce at least a few inches from the
northern Rockies to central South Dakota, with the highest totals
in the Black Hills, Big Horn Mountains and the central to western
Montana ranges.

...Ohio Valley and Great Lakes...
An upper level trough will continue to amplify as it moves east
across the northern Plains and upper Midwest on Monday.  Models
show rain changing to snow, with light snow accumulations north of
the synoptic low moving east through the Ohio valley on Monday. 
Meanwhile, low level northwest flow developing over the upper
Great Lakes will re-establish the threat for lake effect snow
showers, with locally heavy accumulations possible over the
eastern U.P. and northern Lower Michigan. 

The probability of significant icing (0.25-inch) is less than 10
percent.

Pereira