Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
409 AM EDT Thu Apr 07 2022

Valid 12Z Thu Apr 07 2022 - 12Z Sun Apr 10 2022

...Pacific Northwest to the Northern Rockies...
Days 2-3...
A mid-to-upper level shortwave trough and its associated surface
cold front are expected to push across the Northwest into the
northern Rockies Friday night into Saturday.  In its wake, deep
northwesterly flow with embedded energy aloft will follow,
supporting additional showers through early Sunday.  Snow levels
will fall quickly behind the front, dipping below 1000 ft across
portions of the Northwest and the northern Rockies over the
weekend.  Two day totals ending Sunday will likely exceed 8 inches
across the Olympics and a large portion of the Washington and
northern Oregon Cascades, including many of the passes.  Heavier
amounts are likely for the higher peaks.  Locally heavy amounts
are also possible for the Blue Mountains and portions of the
northern Idaho and northwestern Montana ranges.

...Upper Midwest/Western Great Lakes...
Days 1-2...
An anomalously deep closed low will dip southeast from northern
Minnesota into Wisconsin later today.  Northerly winds on the
backside of the low will support the development of lake effect
snow showers, focusing initially along the South Shore of Lake
Superior from northern Wisconsin into the western U.P. of
Michigan, where WPC probabilities indicate accumulations of 4
inches or more are likely, and 8 inches or more are possible by
Friday morning.  As the low continues to track southeast, backing
winds will spread lake effect snow showers farther east along the
U.P., with locally heavy amounts from the Keweenaw Peninsula into
the central U.P. snowbelt.

For Days 1-3, the probability of significant icing of at least
0.25" is less than 10 percent.

Pereira