Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
428 PM EDT Wed Apr 27 2022

Valid 00Z Thu Apr 28 2022 - 00Z Sun May 01 2022

...Northern Rockies to Northern Great Plains...
Days 2-3...
An amplifying negatively-tilted upper trough is expected to move
from the Pacific Northwest into the northern Rockies on Friday,
with heavy snow developing on the north side of the associated
700mb low as it moves across southern Montana.  Widespread
accumulations of 4 inches or more are likely across the mountains
of western and central Montana, with heavier accumulations likely
across some of higher terrain.  This system will continue to
amplify, with a closed low developing as it moves east of the
Rockies into the central Plains late Friday.  As the system
intensifies, some rain changing to snow is expected within the
associated comma head centered over the western Dakotas Friday
night into Saturday.  Apart from the Black Hills, where several
inches are possible, marginal temperatures are expected to limit
the potential for heavy amounts.

...Northeast...
Days 1-3...
Slowed by blocking flow developing upstream, an upper low moving
across the Northeast into the Gulf of Maine overnight is expected
to linger over the region through Friday.  As the upper low moves
east, ongoing precipitation across northern New England is
forecast to change to snow this evening, with snow continuing
across portions of northern Maine into Friday.  Two day snow
totals of 4 inches or more are likely across much of northern
Maine, with localized amounts of 8 inches or more possible.

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

Pereira