Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
330 PM EST Mon Mar 01 2021

Valid 00Z Tue Mar 02 2021 - 00Z Fri Mar 05 2021

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

Low pressure lifts north from eastern Maine rest of this afternoon
with associated rain/snow lifting out before 00Z. In the wake of
this low is a particularly cold mid-level low that is sending an
Arctic front with associated snow squalls east from the eastern
Great Lakes this afternoon, quickly crossing the rest of the
Northeast through the evening. While accumulations from these
squalls should be minimal, briefly intense snowfall rates of more
than 1"/hr, strong westerly winds, and temperatures rapidly
dropping below freezing could whiten the ground and produce
significantly reduced visibility, particularly in upstate NY.
However, the low level flow is not very perpendicular to the
front, so the ability for this activity to reach the coastal
areas/I-95 corridor is considered limited.

Behind this Arctic front, strong CAA will produce periods of LES
in the favored NW snow belts east of Lakes Erie and Ontario. While
duration and intensity is modest (mainly ending tonight), briefly
heavy snow is possible. WPC Snow probabilities for 2 or more
inches are limited to an area of 10 to 20 percent probability just
southeast of Syracuse.

A clipper pushes east-southeast from Ontario into the interior
Northeast Tuesday night. Northern slopes of the Tug Hill Plateau
and the Adirondacks look to get brief moderate snowfall rates with
Day 2 snow probabilities for 4 or more inches 40 to 60 percent
with some additional snow in the northern Greens of VT.


...Southwest to Central Rockies...
Days 2-3...

Upper level low pressure closes well off the northern CA coast
(near 130W) tonight and shifts south well offshore through Tuesday
before turning east. This low crosses southern CA late Wednesday
and tracks to the Four Corners area by Thursday morning. The
influx of Pacific moisture ahead of this low allows for moderate
higher elevation snows for the southern CA ranges (snow level
around 5000ft) as well as the higher ranges (snow levels 5500ft to
6500ft) of southern UT, the Mogollon Rim in AZ, and in particular
the San Juan Range of CO/northern NM. Snow probabilities for 4 or
more inches are currently limited to just the highest peaks of
southern CA and AZ, but moderate to high for 6 or more inches on
Day 3 in the southern UT ranges and San Juans.


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

Jackson