Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
429 PM EDT Tue Mar 24 2020

Valid 00Z Wed Mar 25 2020 - 00Z Sat Mar 28 2020


Day 1-3...

...Western U.S....
A positively-tilted upper trough will continue to settle southeast
across the western U.S. through Thursday.  An associated
low-to-mid level front is expected to provide the focus for
periods of organized heavier snow from the Sierra to the central
Rockies Tuesday night and Wednesday.  Impacted areas on Day 1
(ending 00Z Thursday) are forecast to include the Sierra and the
northern Utah ranges - where WPC PWPF continues to indicate high
probabilities for accumulations of 8-inches or more across the
higher terrain.

This front is expected to stall across the central Rockies, Great
Basin, and the Sierra with additional areas of heavy snow expected
Thursday night into Friday as a well-defined shortwave ejects
eastward across the region.  Impacted areas on Day 2 (ending 00Z
Friday) are forecast to include the east-central Nevada to far
west-central Utah ranges - where WPC PWPF is showing high
probabilities for accumulations of 8-inches or more across the
higher terrain.

...Northern Plains to the Upper Great Lakes...
A mid-level shortwave and associated surface low are forecast to
move across central Canada, with a trailing cold front dropping
southeast across the north-central U.S. Tuesday night.  Mid level
energy emanating from the western U.S. will support the
development of a weak wave that will move east along the boundary,
pushing moisture north of the front.  This along with favorable
upper jet forcing will support a stripe of light to moderate
precipitation across South Dakota early Wednesday before shifting
east across southern Minnesota to northern Wisconsin and the U.P.
of Michigan mid to late day.  Marginal temperatures during the day
should keep accumulations in check, however guidance does show the
potential for banded precipitation, producing locally heavier
precipitation rates which could raise accumulations from eastern
South Dakota to southern Minnesota during the day on Wednesday. 
Potential for locally heavier accumulations is expected to
increase as the system moves farther northeast into the northern
Wisconsin and the U.P. Wednesday evening into the overnight.

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

Pereira