Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
319 PM EST Tue Mar 01 2022

Valid 00Z Wed Mar 02 2022 - 00Z Sat Mar 05 2022

...West...
Days 1-3...

The atmospheric river will continue to funnel Pacific moisture
into the Pacific Northwest and Northern Rockies through Day 1 and
into Day 2. Abnormally warm mid-level temperatures associated with
a strong ridge axis over the Rockies continues to keep snow levels
high. The northern Rockies of western Montana and the tallest
peaks of the Cascades feature the best chances for Day 1 (>40%
probabilities of snowfall exceeding 4"). Day 2 features an upper
trough tracking east into the Pacific Northwest while the right
entrance region of a jet streak becomes positioned over western
Montana. 500mb height falls will result in lower snow levels with
some heavier snowfall in parts of northwest Montana and far
northern Idaho. Latest Day 2 WPC probabilities show a 70% chance
for snowfall totals >4" in the highest elevations of northwest
Montana. It is Day 3 when a deepening upper low tracking into
California ushers a steady stream of moisture into the Sierra
Nevada and the Transverse Ranges. Latest WPC probabilities show
close to a 30% chance for snowfall totals >8" in the higher
elevations of the central and southern Sierras. Snow levels in
Southern California are higher but could still result in >4" of
snow in the highest peaks. Farther north, western Montana is
expected to see more snowfall with WPC probabilities exceeding 4"
around 40% in the highest elevations as the upper trough
responsible for the periods of snow on Day 2 reaches the Northern
Rockies by Day 3.


...Northeast...
Days 1-2...

As the first fast moving frontal system quickly tracks east across
northern New England, most snowfall totals should fall short of 4"
with the exception of perhaps one or two areas in central and
Downeast Maine this evening. Focus shifts to a second wave of low
pressure emerging out of the northern Great Lakes will make its
way towards the Northeast bringing the next round of wintry
weather late Day 1 into early Day 2. This setup is primarily
driven by strong diffluence in the left exit region of a 250mb jet
streak, which will setup over the Northeast around 00Z Thurs. WPC
probabilities of snowfall >4" are highest just downwind of Lakes
Erie and Ontario with the highest probabilities focused in the
Adirondacks and Tug Hill Plateau. Some localized amounts up to 6"
are possible in the higher elevations where westerly up-sloping
low level flow and/or where higher snow ratios are present.
Meanwhile, Downeast Maine also has a swath of higher >4"
probabilities (as high as 30%) as the wave of low pressure
attempts to strengthen just off the coast of Maine.


For Days 1-3, the probability of significant icing of at least a
quarter of an inch is less than 10 percent.


Mullinax