Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
402 PM EDT Sun Oct 16 2022

Valid 00Z Mon Oct 17 2022 - 00Z Thu Oct 20 2022


Days 1-3...
...Upper Great Lakes...
The first significant and impactful lake effect snow event of the
season is expected with several inches of heavy, wet snow across
portions of the U.P. of Michigan and extreme northern Wisconsin
through Tuesday. An amplified upper pattern featuring anomalous
ridging over the western U.S. will allow a deep trough to drop
across the Great Lakes tonight, closing off and remaining centered
over the region through Tuesday. Embedded within this trough will
be a couple of stronger shortwaves helping to foster increased
large scale forcing for ascent. Height anomalies of -2 to -3 sigma
are likely per the recent runs of the GFS while 850 mb
temperatures around -10C (-2 sigma) pivot over the region. Ample
instability atop lake temperatures +8 to 10C along with deepening
moisture will help support the development of locally heavy snow
rates, especially along the higher terrain of the western to
central U.P. into far northern Wisconsin later tonight into Monday
with some heavy snow possible Monday night into early Tuesday.

The latest PWPF from WPC indicates high probabilities of at least
6 inches across the terrain areas downwind of Lake Superior in the
U.P. of Michigan with a localized but significant threat of 12
inches or more. With colder air gradually working into Lower
Michigan, rain will mix with and change to snow over some interior
and elevated locations on Monday with snow totals possibly
reaching 2-3" in the favored areas of northern Lower Michigan from
near Gaylord to south of Traverse City. As the colder air spills
eastward, some minor accumulations downwind of Lake Erie across
extreme western NY and northwest PA of a few inches will be
possible as well as the spine of the central Appalachians.


The probability of significant icing is less than 10 percent.

Pereira/Fracasso/Taylor