Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
403 AM EST Sun Mar 06 2022

Valid 12Z Sun Mar 06 2022 - 12Z Wed Mar 09 2022

...Western U.S....
Days 1-3...
An upper low will continue to move across the Southwest into the
Four Corners region this morning before transitioning to an open
wave as it moves across the Rockies and into the High Plains later
today.  The associated mid-to-upper level dynamics will likely
support additional snows across the Colorado and far northern New
Mexico ranges, with WPC probabilities indicating widespread
potential for snowfall accumulations 4-8 inches across the higher
terrain.  Locally heavier accumulations are most likely across the
San Juan and Sangre de Cristo mountains, where the probabilities
for 8 inches or more are highest.

The potential for significant snowfall accumulations is likely to
wane by Sunday night as the shortwave continues to progress
through the Plains.  Meanwhile, a northern stream shortwave
dropping south from western Canada will support some light
accumulations over the northern Rockies before returning the
change for light accumulations back into the central Rockies on
Monday.

Beginning Monday night, and continuing through Tuesday into early
Wednesday, a broader scale trough is forecast to amplify south
across the Pacific Northwest and northern Rockies -- bringing much
colder air into the region.  Increasing low-to-mid level
frontogenesis overlapped by left-exit region upper jet forcing
will increase the potential for heavy snow from the northern
Cascades to the northern Rockies.  Across the Northwest, WPC
probabilities indicate accumulations of 4-8 inches are likely,
with local accumulations of a foot or more possible across the
higher elevations of the northern Cascades and the Blue Mountains
by early Wednesday.  Across the Rockies, accumulations of 4-8
inches are likely from the northern Idaho and western Montana
ranges to the northern Utah mountains.  Local accumulations of a
foot or more are most likely in the northern Idaho ranges,
including the Bitterroot and Clearwater mountains.

...Northeast...
Days 1...
Warm advection precipitation ahead of a well-defined system moving
across the Upper Great Lakes will continue to spread across
northern New York and New England this morning.  Falling initially
as a wintry mix, light ice accumulations are possible from
northern New York through northern Vermont and New Hampshire into
northern Maine.  Across northern Maine where the deeper colder air
is expected to remain in place a little bit longer, a few inches
of snow is possible before changing over to a wintry mix and rain
later today.

...Central Plains to the Northeast...
Days 1-3...
The upper trough moving into the central Plains Sunday night is
forecast stretch northeastward ahead of an amplifying northern
stream trough over the Upper Midwest.  Ample moisture advection
afforded by deep southwesterly flow will support an expanding area
of precipitation from the mid Mississippi Valley into the Great
Lakes and Ohio Valley Sunday night and Monday morning.  Low-to-mid
level frontogenesis along with cooling temperatures will support
snow developing on the northwest side of the associated surface
low as it tracks northeastward from the mid Mississippi Valley
toward the Great Lakes Sunday night.  Light snow accumulations are
expected from as far west as southeastern Nebraska and
northeastern Kansas, spreading east across northern Missouri and
Iowa into northern Illinois and southern Wisconsin by Monday
morning.  Snow is expected to continue east across northern Lower
Michigan, with right-entrance region upper jet forcing providing a
slightly greater potential for heavier accumulations.  The low is
forecast to continue northeastward near the Lower Great Lakes and
into the Northeast on Monday.  This will bring the next chance for
a wintry mix, with some light snow and ice accumulations, back
into northern New York and New England. 


Pereira