Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
303 AM EST Mon Nov 02 2020

Valid 12Z Mon Nov 02 2020 - 12Z Thu Nov 05 2020

...Great Lakes/New York/Vermont...
Day /2...

The initial strong cold advection over rather warm Lake Ontario
waters (generally mid 50s to 60F lake temps) is forecast to
produce additional snow showers in the Tug Hill area of NY.  A
potent shortwave is progged track southeast from north of the
Great Lakes today, crossing New England tonight, and offshore
Tuesday. An enhanced area of snow is likely east of Lake Ontario
where fetch/LES enhancement is likely, so locally heavy snow is
expected in the Tug Hill area.  Boundary layer west winds optimize
cross lake fetches late this afternoon and evening, which then
turn upslope into the Tug Hill and produce expected heavy snow.
Day 1 snow probabilities are moderate to high for a foot in the
Tug Hill.

Moist northwest flow with 300 mb divergence maxima and 700 mb
vertical velocity maxima favors accumulating snow showers across
the western to northern Adirondacks into the northern Green
Mountains where there are low to moderate Day 1 snow probabilities
for 6 or more inches in the highest Adirondacks and Green Mtns. 
The progressing shortwave crossing interior New England tonight
brings  burst of ascent to the White Mountains for a period
tonight before departing tot he coastal water Tue morning.

The event winds down on Tuesday as low level ridging crosses the
lakes and drier air aloft advects into New York/New England.

...Northern Maine...
Day 1...

The rapidly deepening low in Maine is forecast to move quickly
north into Canada today. Strong diffluence within a robust jet
streak and rapid height falls will likely lead to a broad
precipitation shield, with some enhancement of precipitation
likely in a mid level deformation zone in western Maine.  However,
with the steady north movement of the low, the precip shield
should also move steadily north. The snow should end with the
precipitation shield this afternoon over northern Maine.  Because
of the short duration of snow, Day 1 snow probabilities are low
for 4 or more inches over the northern Maine.

The probability for significant ice (0.25" or greater) is less
than 10 percent all 3 days.

Petersen