Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
327 PM EST Sun Feb 28 2021

Valid 00Z Mon Mar 01 2021 - 00Z Thu Mar 04 2021

...Northern Great Lakes through the Northeast...
Days 1-2...

A lobe of an Arctic low is currently along the northern
Manitoba/Ontario border. A southern stream shortwave is riding a
strong SWly jet ahead of this lobe and is currently over the U.P.
of MI and a reinforcing northern stream shortwave trough is
pushing southeast over southern Manitoba on a strong NNWly jet.
The leading, southern stream wave (currently producing heavy snow
in the U.P.) lifts well into Quebec tonight, allowing an initial
cold front to shift across New England Monday morning. A light
wintry mix can be expected over the Adirondacks and mountainous
New England tonight in the warm air advection ahead of this front.
Northern Maine is cold enough to allow a burst of snow with the
cold front...HREF probabilities for 1"/hr rates are moderate from
12Z to 16Z across far northern Maine where Day 1 snow
probabilities for 6 or more inches are 20 to 40 percent.

Monday afternoon the arctic cold front associated with the
reinforcing shortwave trough shifts southeast across New England.
An area of snow will likely accompany this feature as ascent is
provided through rapid height falls and PVA. However, somewhat
limited moisture and fast progression should limit snowfall
accumulations outside of lake effect snow belts. Day 1.5 WPC snow
probabilities for 2 or more inches are moderate for the northern
Adirondacks and interior mountainous New England (Greens and
Whites) from upslope enhancement. Additionally, some lake effect
snow is likely E/SE of Erie and Ontario, but forecast soundings
indicate the DGZ struggles to saturate so LES accumulations are
forecast to be modest, generally around 2 inches. Behind the
arctic front, the environment continues to look primed for snow
squalls across Upstate New York, parts of New England, and
potentially into northern PA. While accumulations from these
squalls should be limited, briefly intense snowfall rates and
gusty winds are likely Monday night with Day 1.5 snow
probabilities for 1 or more inches generally above 5 percent
across upstate NY.


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

Jackson