Probabilistic Heavy Snow and Icing Discussion
NWS Weather Prediction Center College Park MD
352 AM EST Thu Jan 27 2022

Valid 12Z Thu Jan 27 2022 - 12Z Sun Jan 30 2022


...Southern Appalachians through the Mid-Atlantic...
Days 2-3...
The focus remains high on a pair of shortwaves originating over
western North America and their potential interaction over the
eastern U.S. later this week.  Models are in general agreement
that a shortwave trough dropping southeast through the northern
Rockies this morning will dive into the Four Corners region later
today before swinging east across the southern Plains into the
southeastern U.S. There it will begin to phase with a northern
stream trough amplifying over the Great Lakes/Ohio Valley on
Friday.  This will spur the development of surface low off of the
Carolina Coast by late Friday.  Models also agree that the system
will then begin to rapidly intensify as it tracks north along the
Mid Atlantic to Northeast coasts Friday night through Saturday. 
The upper trough is expected to assume a negative-tilt as it lifts
north, with a closed low likely developing over New England by
late Saturday.  This along with a coupled upper jet structure will
support the rapid intensification of the surface low, with most
models agreeing on central pressure in the 970s or lower as the
system tracks along the New England coast late Saturday into early
Sunday.  Unfortunately there remains a great deal of model spread
with respect to the timing and longitudinal track of the low --
fostering continued uncertainty with regard to potential impacts
from the Mid Atlantic to New England.

It still appears that the heaviest snows will likely fall along
coastal New England, with WPC probabilities for snow accumulations
of 8 inches or more highest from eastern Massachusetts, including
the Boston metro, to Down East Maine.  Along this axis, WPC
probabilities along indicate that locally heavier amounts of a
foot or more are likely.  The combination of heavy snow, along
with strong winds will likely produce notable impacts across the
region.

Farther south where confidence in potential impacts is lower, WPC
probabilities indicate that snow accumulations of 4 inches or more
are likely from southern New England to southeastern Virginia.

There is also the potential for locally heavy accumulations
farther west across the central and southern Appalachians.  As a
cold front associated with the northern stream trough drops into
the region, WPC probabilities show the potential for some
localized amounts of 4 inches or more across portions of the West
Virginia, southwestern Virginia, and along the Tennessee-North
Carolina border.

For days 1-3, the probability of significant icing is less than 10
percent.

Pereira

~~~ Key Messages for Jan 28-30 East Coast Winter Storm ~~

-- A winter storm is likely to create significant impacts across
New England Friday night through Sunday. Notable impacts may also
extend south along the East Coast through North Carolina.

-- Across New England, heavy snow and strong winds are likely
which could lead to blowing snow, scattered power outages, and
some damage. Additionally, significant coastal impacts are
possible, including coastal flooding and beach erosion.

-- Farther south along the coast, from New York City to northeast
North Carolina, moderate to heavy snow is possible, but confidence
in potential impacts is lower.

-- This forecast continues to evolve. Please check for updates and
your local forecast at weather.gov.