Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
422 AM EST Sun Feb 16 2020

Valid 12Z Sun Feb 16 2020 - 12Z Wed Feb 19 2020


Days 1-3...

...Pacific Northwest to the Northern and Central Rockies...
As a shortwave trough continues to dig southeast across the
Northwest into the northern Intermountain West and Rockies, snows
will continue across the mountains of the Pacific Northwest and
northern Rockies, while spreading farther south into the central
Great Basin and Rockies on Sunday.  Areas impacted by additional
snowfall accumulations of a foot or more are likely to include the
western Wyoming, as well as the south-central Wyoming to
north-central Colorado ranges.

...Great Lakes and Northeast...
Shortwave energy moving east along the leading edge of the western
U.S. trough into the northern Plains is forecast to interact with
a more northerly wave dropping southeast from central Canada --
supporting a deepening surface low lifting northeast from the
lower Missouri valley into the western Great Lakes region on
Monday.  Models show favorable upper jet forcing along with
low-to-mid frontogenesis producing a stripe of light to moderate
snows from northern Iowa and southern Minnesota Monday morning to
northern Michigan by late in the day.

Models show the low tracking northeast of the Upper Great Lakes
into eastern Ontario and western Quebec with widespread warm
advection precipitation moving across the Northeast on Tuesday. 
While areas from northern Pennsylvania to southern New England are
expected to begin as snow but quickly change to rain, areas to the
north, including the Adirondacks and northern New England are
forecast to remain primarily snow -- resulting in at least a few
inches of accumulations across those areas.  A period of
lake-enhancement may further bolster amounts from the Tug Hill
region into the southern Adirondacks. 

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

Pereira