Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
314 PM EST Sat Jan 25 2020

Valid 00Z Sun Jan 26 2020 - 00Z Wed Jan 29 2020

...Northwestern CONUS...

Days 1-3...

In a series of progressive shortwaves to impact the Pacific
Northwest, the first wave arrive later tonight into Sunday morning
and snowfall accumulations are expected to primarily affect
portions of northwest CA, western OR, and western WA with the
highest probabilities of heavier snow totals across the WA
Cascades due to relatively high snow levels elsewhere. Quick to
follow behind the initial shortwave is another one that primarily
focuses the best lift/moisture on the western WA Cascades Sunday
into Sunday night.

Across portions of central/northern ID and northwest MT, several
inches are snow are expected as the repeating shortwaves track
through the central/northern Rockies. While no particular system
is likely to produce widespread heavy snowfall, the cumulative
affect over the next 3 days will produce considerable
accumulations for the highest elevations.

Lighter snowfall totals will spread southeast across portions of
the Great Basin and CO during the next 3 days, particularly days
1-2. Snow should taper Tuesday morning as the upper trough departs
and moves east onto the Plains.


...Midwest/Great Lakes/Mid-Atlantic/Northeast...

Days 1-3...
An area of low pressure developing over the Mid-Atlantic today
will track inland up the Eastern Seaboard through Sunday. The
combination of strong low to mid level warm advection and the
inland track is likely to result in a progressive bout of wintry
mix from snow to sleet/freezing rain and rain. Overall, amounts
will be on the lighter side through this event. Measurable amounts
of freezing rain are expected to be confined to northern New
England (VT/NH/ME) and as the low tracks northeastward, much of
northern Maine where accumulations could exceed 0.10 inch.

Strong cyclonic flow in the wake of the departing system will
bring a prolonged period of enhanced moisture and lift across both
Lake Erie and Lake Ontario. Aided by the favorable west/southwest
flow and enhancement due to topography, several inches of snow are
expected in the lee of both lakes across southwest and upstate New
York.

On Monday, amounts are lighter as a progressive front crosses the
lower lakes, with lighter snow amounts following shorter cross
lake trajectories and weaker lift. Most locations on Monday are
forecast to get an inch or two, with no heavy snow areas
identified.

The probability of 0.25 inches of freezing rain is less than 10
percent Days 1-3.

Taylor