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720
FXUS61 KLWX 171441
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
941 AM EST Fri Jan 17 2025

.SYNOPSIS...
A brief period of high pressure builds over the region today
before multiple waves of low pressure push through the region
this weekend. A very cold Arctic airmass will then build into
the region in the wake of Sunday`s low pressure system during at
least the early to middle portions of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
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Current satellite observations continue to show a persistent
deck of stratocu this morning in a gravity wave pattern. This
layer is showing signs of thinning/eroding, and may disperse
rather quickly around or just after midday.

High pressure will build across the Mid-Atlantic today. This
will result in near normal temperatures and mostly sunny skies
once drier air moves in and finally burns off this stratocu
layer. A large trough of low pressure is expected to dig across
the central CONUS, marking the leading edge of an Arctic
outbreak, will approach the area tonight.
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&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...
Some shower activity is possible ahead of the aforementioned low
pressure system on Saturday, but overall amounts continue to
look on the light side. A light rain/snow mix is possible over
the higher terrain in particular Saturday morning, but could
even make it into the lower elevations, albeit briefly and with
little/no accumulation.

A relative lull is expected Saturday late afternoon and evening
as the initial Arctic front pushes to the east and a wave of
surface low pressure goes with it, at least outside of the
mountains, where snow looks to continue. A second wave of low
pressure will take shape over the TN Valley, which will become
our Sunday winter storm.

Precipitation chances continue to increase on Sunday with
guidance trending towards a snowier solution areawide. At least
a light accumulating snowfall is becoming increasingly likely
across most of the forecast area as a fast-moving, yet potent,
low pressure system slides by to our south. The arctic front
Saturday will have ushered in sub-freezing air to much of the
region by the time of precipitation onset. There may be some
thermal issues towards southern MD and the VA Piedmont, but for
the most part, looks like an all snow event for many.

Initial forecast amounts are in the 1 to 3 inch range in those
areas where thermal issues may exist at the onset, with 3 to 4
inches seems most likely along and north of I-66/US-50. The
upslope areas will of course see substantially more, and over a
bit of a longer timeframe. For most, this system will be very
quick-moving, lasting around 6 to 12 hours or so.

Most precipitation should wind down Sunday evening, with dry
conditions expected for areas east of the mountains. This will
give way to a very cold night, but not the coldest in the
forecast...

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...
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Longwave trough axis will be overhead during the first half of next
week bringing coldest air since at least Dec 2022. 2014 also had
very cold air of similar magnitude to what we are going to
experience early next week. Looking at records, only one or two
daily records will likely be broken, but widespread record cold
temperatures seem unlikely at this time. For Martin Luther King Jr
Day/Inauguration Day, temps will be around 20 with wind gusts up to
30 mph creating bitterly cold wind chills in the single digits all
day and falling below zero at night. Ensemble guidance generally
suggest very cold and dry conditions much of next week with a slight
chance of some snow making into southern MD Tue night-Wed associated
with the winter storm expected to hit the South. Light snow showers
also appear possible with main area of vorticity/trough axis
crossing the area Tue afternoon, but very dry Arctic air mass likely
won`t support anything measurable.

Big warmup, relatively speaking, is expected for the second half of
next week as pattern de-amplifies and coldest anomalies lift
out of the region.
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&&

.AVIATION /15Z FRIDAY THROUGH TUESDAY/...
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Persistent gravity waves remain situated over the region as of
1430Z, with cloud decks around 4-5 kft. These should burn off
around or just after midday (16Z-18Z) as some drier air moves
in aloft.

VFR conditions are expected through tonight, though sub-VFR
returns by Saturday as another frontal system moves in. Winds S
today become NW by Saturday night. Overall, precip amounts look
light and in the form of rain Saturday, though there could be a
brief mix of rain and snow at onset Saturday morning.

Sub-VFR conditions are once again likely on Sunday with an
increasing likelihood for accumulating snow throughout the day,
and possibly into the evening. Winds out of the NNW will be
gusting around 15 to 20 knots. VFR conditions build in on
Sunday night with winds turning out of the northwest.

Gusts to 30 kt Monday, diminishing Tue afternoon and evening, but
picking up again Wednesday. Very cold wind chills will be the main
impact to ground operations at terminals.
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&&

.MARINE...
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High pressure will build into the region today, then move
offshore and could result in some channeling tonight, but
confidence was too low for SCA issuance.

Winds will then shift to the northwest and increase by Saturday
night as an Arctic cold front moves through.

SCAs are expected by Sunday afternoon as winds pick up significantly
out of the north. Snow is also expected Sunday as a quick-moving
low pressure system traverses the region.

SCA conditions are expected Monday into Tue morning. Freezing spray
is also likely. Winds diminish briefly Tue night, but strengthen
again Wednesday
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&&

.LWX WATCHES/WARNINGS/ADVISORIES...
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DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.
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&&

$$

SYNOPSIS...DHOF/CJL
NEAR TERM...DHOF/CJL
SHORT TERM...DHOF/CJL
LONG TERM...LFR
AVIATION...LFR/DHOF/CJL
MARINE...LFR/DHOF/CJL