Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
300 PM EDT Thu Apr 28 2022

Valid 00Z Fri Apr 29 2022 - 00Z Mon May 02 2022

...Northern Rockies to Northern Great Plains...
Days 1-2...
A negatively-tilted upper trough will track from the Pacific
Northwest to the northern Rockies overnight.  Models continue to
present a good signal for locally heavy accumulations from the
Southwest Montana ranges to the central Montana mountains,
including the Little Belt, Crazy, and Big Snowy mountains.  In
addition to ample upper forcing, strong northwesterly to northerly
flow on the northwest side of a 700 mb low moving along the
Montana-Wyoming border is expected to help bolster amounts across
this region.  Southwesterly flow ahead of the low and its
associated front may help produce some locally heavy amounts along
the Bighorn Mountains.  WPC probabilities indicate that
accumulations of 4 inches or more are likely, with accumulations
of 8 inches or more possible across the higher elevations.

As the low moves east of the Rockies, guidance continues to show a
closed low developing over the central Plains on Saturday.   Some
rain changing to wet snow is possible within the associated
deformation zone over the Dakotas; however, little to no
accumulations are expected outside of the Black Hills. 

...Maine...
Days 1...
A closed low centered over the Bay of Fundy/Nova Scotia is
forecast to drift slowly east, with snow diminishing across
northern and eastern Maine on Friday.  Overall, an inch or two of
additional accumulation is expected across northern Maine, with
some higher amounts possible over the mountains. 


For days 1-3, the probability of significant icing greater than
0.25 inches is less than 10 percent.

Pereira