Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
434 PM EST Mon Dec 02 2019

Valid 00Z Tue Dec 03 2019 - 00Z Fri Dec 06 2019

Days 1-3...

...Northeast...
An ongoing winter storm is forecast to continue into Tuesday
across portions of the Northeast as the associated upper level low
deepens and lifts to the north along the coast.

An upper low centered over the Mid Atlantic states Monday evening
is forecast to gradually deepen as it lifts along the coast
overnight.  Surface low pressure moving east of Long Island is
expected to strengthen as it tracks east of Cape Cod toward the
Gulf of Maine overnight.  Low-to-mid level frontogenesis and mid
level deformation will support light to moderate precipitation
west of the low, producing at least an additional inch or two of
snow from the NYC metro northward into the Hudson Valley and
western Connecticut and Massachusetts Monday evening.  Meanwhile,
snow is expected to develop farther east across eastern
Massachusetts and continue through the overnight, with a few
inches possible by daybreak along the I-95 corridor.  During the
day on Tuesday, moderate to heavy snow is forecast to lift farther
north into Maine, but not before beginning as an icy mix along the
coast.  The heaviest accumulations are expected to center across
central Maine, where several inches are possible before the system
tracks east into Nova Scotia Tuesday evening.

...Great Lakes...
Beginning Tuesday night and continuing through Wednesday, a pair
of shortwave troughs dropping southeast across the region will
bring deeper moisture and a period modest cold air advection --
supporting lake effect snow showers.  While modest cold air
advection aloft is expected to limit the potential for heavy
amounts, orographic lift is expected to help bolster totals in the
Tug Hill region and along the Allegheny Plateau in western New
York and Pennsylvania, where several inches are possible by early
Thursday.

...Southern California to the Central Rockies...
A closed low centered west of Northern California is expected to
drop southwest before weakening and eject east across Southern
California on Wednesday.  This will bring a period of locally
heavy snow to the southern Sierra and southern coastal ranges on
Wednesday.  These snows are expected to diminish as the system
moves quickly to the east Wednesday evening.  High elevation snows
are expected to accompany the system as it moves across the
southern Great Basin and into the central Rockies Wednesday night.


For Days 1-3, the probability of 0.25 inches of icing is less than
10 percent.

Pereira