354
FXUS61 KLWX 210745
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
345 AM EDT Fri Aug 21 2026

.WHAT HAS CHANGED...
Dense Fog Advisory is in effect for portions of western MD and
eastern WV until 8 AM, primarily for the valleys.

Made substantial changes to the aviation section to account for
less low clouds this morning.

&&

.KEY MESSAGES...
- 1) Thunderstorm chances increase Friday night and continue
  through Sunday.

- 2) Drier conditions anticipated early next week.

&&

.DISCUSSION...
KEY MESSAGE 1...Thunderstorm chances increase Friday night and
continue through Sunday. Lowering humidity and drier conditions
early next week.

The region remains under the influence of an upper trough over
the next several days. A subtle piece of shortwave energy will
round the base of the trough this evening/tonight and lift
through the region into Saturday. Meanwhile, the cold front
that pushed through last evening will remain nearly stationary
across southeastern VA through tonight. An area of low pressure
will develop near the VA Tidewater as a result during this time,
with rain expected for much of the region by Saturday morning.

The main axis of the upper-level trough will begin to shift
slightly east late Saturday into Sunday, which will in turn
push a much more potent piece of upper-level energy across the
Ohio Valley into the Adirondacks. On the front end of this,
there could be some lingering convection moving out of the Ohio
Valley into our western zones later Saturday. This will carry a
non-zero severe weather threat into the Alleghenies Saturday
evening/night, with damaging winds the primary threat.

By Sunday, the actual front will push through the region, and
may have enough left in the tank to spark a few more storms east
of I-95 in the afternoon/evening hours. Severe threat looks
rather low at this point, but will continue to monitor.


KEY MESSAGE 2...Drier conditions anticipated early next week.

By Monday, the weekend`s frontal boundary should transition
offshore, and upper-level patterns transition to zonal flow as
surface high pressure builds over the Appalachians. Dewpoints could
broadly get to below 60F by Tuesday morning as this high pressure
builds, allowing for much drier conditions within the region.
These conditions to persist until midweek, with temperatures
trending a bit cooler than average to start between Monday and
Tuesday but slowly creeping up later in the week as high pressure
builds.

Beginning Wednesday, an upper-level trough begins to form over the
Great Lakes and track southeast, with a surface low anticipated to
potentially track through the Mid-Atlantic by Thursday. A few
showers & thunderstorms are possible during this period as the
low moves through, and humidity & temperatures rise back to late-
August normals during this time.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...
Model guidance backed off significantly on lower clouds
developing this morning, so removed those from almost all of the
TAFs. MRB could still see some lower clouds/fog, but for now
that is staying just to the west. VFR conditions are expected
elsewhere today.

Showers and thunderstorms do return to the terminals from the south
Saturday morning as an area of low pressure develops along the
coast and pushes up along the stalled front nearby. For now,
have added PROB30s into the 06z TAFs, owing to uncertainty with
start time. Also, kept it SHRA for now, as thunder may be a bit
more likely into the afternoon hours, but going to continue to
evaluate that as we get closer in time. Coverage of showers and
thunderstorms will be scattered to numerous throughout the day
with temporary restrictions at times. Winds will be out of the
north and northwest today and Saturday at less than 15 kts.

Northwesterly winds gust up to 25 knots on Sunday at MRB with
eastward terminals blowing around 10 knots in the afternoon. Showers
and thunderstorms are possible during the afternoon, leading to
potential flight restrictions. Probabilities remain pretty low,
with the metro terminals below 30 percent POPs.

Winds shift to westerly on Monday and Tuesday with VFR
conditions expected.

&&

.MARINE...
Winds will be out of the north and northwest at less than 15
kts. Sub-SCA level conditions are expected Friday with winds
still out of the north/northwest at less than 15 kts.
Thunderstorm activity will be limited with rain chances
returning from the south late Friday night into Saturday
morning.

More scattered to numerous showers and thunderstorms are
expected Saturday afternoon and evening. Winds will turn more to
the northeast at less than 15 kts.

Could see some storms over the waters on Sunday as well, but
chances remain around 30 percent for most.

Northwest winds on Sunday shift to westerly on Monday, remaining
below SCA criteria both days. There is a chance for showers and
thunderstorms on Sunday, although chances are highest west of the
waters. Should storms track over the waters, SMWs are possible.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Dense Fog Advisory until 8 AM EDT this morning for MDZ501-502-
     509-510.
VA...None.
WV...Dense Fog Advisory until 8 AM EDT this morning for WVZ050-503-
     504.
MARINE...None.

&&

$$

DISCUSSION...CJL/SRT
AVIATION...CJL/SRT
MARINE...CJL/SRT

NWS LWX Office Area Forecast Discussion