FXUS61 KLWX 040904
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
404 AM EST Sat Jan 4 2025
.SYNOPSIS...
High pressure will briefly build in by tonight. A strong low
pressure system will bring wintry precipitation late Sunday into
Monday. Below normal temperatures continue through next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Strong high pressure is building southeastward from central
Canada with low pressure situated over Quebec. Broad troughing
encompasses the eastern US. Upslope snows are dwindling this
morning with additional accumulations of an inch or two at most.
However, winds are still strong which will reduce visibility in
falling snow and result in blowing/drifting of the snow on the
ground. A Cold Weather Advisory also remains in effect for the
high peaks due to wind chills less than -10.
Elsewhere, expect cold and blustery conditions today, with winds
gusting 20-35 mph. This will result in wind chills in the teens
and 20s through the day with highs only in the upper 20s and
mid 30s. Stratocumulus may tend to expand across the northern
half of the area through the day before clouds finally retreat
tonight.
Temperatures will drop into the teens to lower 20s tonight for
much of the area with single digits in the Alleghenies.
Additional Cold Weather Advisories for the high Alleghenies may
need to be considered, although winds will be gradually
diminishing.
&&
.SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/...
The focus for Sunday and Monday will be the potent low pressure
system moving from the Mid Mississippi Valley to the east coast.
Precipitation will spread into the area late Sunday afternoon
and into the evening (perhaps not reaching northeast Maryland
until late Sunday night). While not a classic cold air damming
set up, the antecedent cold airmass will be plenty supportive
of wintry precipitation across the entire area. With 00Z
guidance, there are essentially two camps, although both offer
the potential for a heavy frontogenetic snow band to the north
of the warm nose. A northern solution would result in mixed
precipitation up to the Potomac River/US-50 or so, with the
heaviest snow across the northern half of the area (and close to
a quarter inch of ice south of I-64). A southern solution would
result in the heaviest snow across the southern half of the
area, with far northern/northeast Maryland receiving a minimum
of snow. It`s also worth noting temperatures could warm enough
Monday for Nelson and St. Marys Counties to change to rain. In
the end, there`s a strong signal for the potential of heavy snow
and/or a mix that includes significant sleet and freezing rain
across most of the forecast area. Therefore, Winter Storm
Watches have been issued. For worst-case scenario planning, the
potential band of 8-12 inches of snow could set up nearly
anywhere within the forecast area. Precipitation will wind down
Monday night. However, there is an increasing signal for wrap-
around snow. Steepening lapse rates through the dendritic snow
zone in a cooling column could result in another round of
locally heavy, fluffy snow on the back end. Hopefully some of
these details can be refined in the next 24 hours.
