FOUS11 KWBC 070717
QPFHSD

Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
317 AM EDT Tue Apr 7 2026

Valid 12Z Tue Apr 07 2026 - 12Z Fri Apr 10 2026

...Northern Adirondacks, Green & White Mts... Day 1...

Strung out vorticity associated with a compact shortwave will swing
from the Great Lakes to the Northeast today. The modest height
falls and PVA will lead to a compact low pressure developing along
an inverted trough, and as this feature moves east it will bring
periods of moderate to heavy snowfall through early tonight. This
event will contain two primary mechanisms for locally heavy snow.

The first will be along the inverted trough immediately ahead of
the wave of low pressure. In this area, the total snowfall is
expected to be minimal, but periods of convective snow showers are
expected as low-level convergence drives ascent into an airmass
with modest instability (SBCAPE 200-300 J/kg). With pockets of
low-level fgen additionally driving ascent, some areas, especially
across Upstate NY and central/southern New England could receive
multiple rounds of snow showers with briefly heavy snow rates,
gusty winds, and periodic visibility restrictions.

The more substantial snowfall accumulations are expected behind the
wave of low pressure as CAA develops to produce low-level fgen, and
NW flow drives substantial upslope enhancement into the Adirondacks
and Greens. The coverage and intensity of this snowfall is again
expected to be modest, but where upslope flow is most pronounced
and overlaps with the leading weak warm advection, WPC
probabilities suggest a 40-70% chance of 4+ inches of snow,
especially across the White Mts of NH and ME. Probabilities for at
least 2 inches of snow are 40-60% across a larger region
encompassing the northern Adirondacks and Green Mts of VT.
Developing deformation, although modest, overlapping this CAA could
cause this swath of snowfall to progress all the way to the
Atlantic coast of Massachusetts with a corridor of heavy snow rates
reaching the Portland/Boston area Tuesday evening, albeit with
minimal accumulations.


Snell/Weiss


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