014
FXUS61 KLWX 091844
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
244 PM EDT Wed Sep 9 2026

.WHAT HAS CHANGED...
Adjusted winds over the waters up slightly tonight. Otherwise,
no significant changes were made to the forecast.

&&

.KEY MESSAGES...
- 1) A cold front brings showers and a few thunderstorms through
  late in the week.

- 2) Daily shower and thunderstorm chances continue this weekend
  with hot temperatures return next week.

&&

.DISCUSSION...
KEY MESSAGE 1...A cold front brings showers and a few thunderstorms
through late in the week.

A couple of weak surface troughs were draped across the area as
of mid afternoon - one from near Baltimore MD to Charlottesville
VA, and another near I-81. Subsidence closer to high pressure
offshore was suppressing cumulus development east of the Blue
Ridge in association with the eastern trough. To the west,
increasing moisture and modest CAPE were resulting in an
expanding cumulus field. Lift overall is weak and instability is
modest, with several lingering stable inversions and weak lapse
rates aloft. This should keep convective activity isolated and
shallow (probably not producing much if any lightning), and
limited to in the vicinity of the western surface trough
near/west of the Blue Ridge back to the Appalachians.

Mid/upper jet forcing increases tonight through Thursday as a
surface cold front approaches from PA and WV. Thunderstorms that
develop over the OH Valley this afternoon are expected to
approach the Appalachian crest in weakening form after midnight.
This activity should continue to readily weaken as it runs out
of instability and forcing as it moves eastward toward daybreak,
though a couple of showers can`t be ruled out as far east as the
metros Thursday morning.

A strong but flattening mid/upper jet will swing by to the north
Thursday into Thursday night, with broad ascent in the right
entrance region overhead. Increasing fgen and an associated
frontal wave look to pivot west to east across north-central VA
late Thursday afternoon into Thursday evening, then move east of
the Chesapeake Bay overnight. Limited heating through abundant
clouds as well as poor lapse rates, high mid-level moisture and
modest moisture in the low levels due in part to downsloping
flow will all keep instability limited. The greatest CAPE will
likely be around 1000-1500 J/kg across central VA where the most
heating and highest low-level moisture content is anticipated.

Some storms may tend to cluster heading into tomorrow evening
given forcing along the front and increased flow aloft, but the
modest CAPE/DCAPE should keep any severe weather threat rather
limited for wind and hail. Still, can`t rule out a briefly
stronger, more organized rotating storm in the vicinity of the
front/wave in the evening across central VA to southern MD.

The front will slowly but steadily drop southward heading into
Friday. Some shower activity may linger or redevelop in the
vicinity of the front near the I-64 corridor, but most of the
time/area should be dry Friday unless the front slows down much
more significantly.


KEY MESSAGE 2...Daily shower and thunderstorm chances continue
this weekend with hot temperatures return next week.

On Saturday, surface high pressure over New England shifts offshore
as a cold front approaches from the northwest. Surface winds shift
to southerly, ushering in a more humid airmass. With increased
humidity, showers and thunderstorms are possible Saturday and Sunday
although are expected to remain below severe criteria.

Going into next week, precipitation chances linger but remain low
(less than 30%). A low pressure system is currently forecast to
track across the Great Lakes with the associated cold fronts
impacting the Mid-Atlantic. Temperatures will be in the upper 80s
(upper 70s in the mountains) each day with high humidity values
yielding heat indices in the low 90s for mountain valley regions or
locations east of the Blue Ridge.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
South to southwest winds gust to around 20 knots into this
evening between high pressure offshore and a cold front over the
OH Valley. Direction may be somewhat variable/a bit more
westerly near KMRB in close proximity to a surface trough, and
could perhaps back to a bit east of south at KDCA/KMTN given
influences from the Potomac River and Chesapeake Bay. VFR should
prevail through much of the night, with a low chance of LLWS as
a LLJ moves overhead (though steady surface winds and not a ton
of direction change in the lowest couple thousand feet should
keep that threat low). A pop up shower can`t be ruled out near
KMRB until about sunset, but most activity should hold off until
well after midnight at the earliest. Weakening activity
approaches 06Z-12Z but confidence in impactful precip are very
low as of the 18Z TAF issuance.

Winds shift to the west and northwest Thursday as a cold front
crosses. Confidence for showers grows Thursday afternoon and
especially Thursday evening as a frontal wave moves overhead.
Thunderstorms are possible, especially south of I-66/US-50, but
confidence is too low to include this far out in the metros.
Numerical guidance does not have a ton of fog/low clouds later
Thursday night into Friday morning after the precip exits, but
the MAV/MET have widespread dense fog. VFR should return by
Friday afternoon as winds shift to the north and then east,
with the potential for a shower or storm near KCHO as the front
remains stalled nearby to the south.

Daily afternoon precipitation chances could bring brief periods of
sub-VFR conditions this weekend. Gentle southerly winds continue
Saturday before weakening and turning to westerly by the end of the
weekend.

&&

.MARINE...
South to southwest winds will increase into this evening.
Although the direction probably won`t be exactly aligned with
the main channel of the Chesapeake Bay, some enhancement is
still anticipated. The strongest winds will be late this evening
into the overnight when gusts to around 30 knots are possible
over the main channel of the Chesapeake Bay into the eastern
tributaries. Some hi-res guidance even has brief gale conditions
which seems unlikely but will be monitored closely.

Showers and a few thunderstorms are anticipated late Thursday
into Thursday night. A few Special Marine Warnings are possible
especially south of Washington DC to Annapolis MD. Winds shift
to the west and northwest Thursday as a cold front crosses, then
shift to north and east through Friday as the front stalls to
the south.

Winds shift to southerly on Saturday with southerly channeling
yielding Small Craft Advisory criteria winds in the afternoon. Winds
diminish overnight and remain below SCA criteria on Sunday.

&&

.TIDES/COASTAL FLOODING...
Tide levels will remain elevated (0.5 to 1 ft above normal)
through Thursday morning. Sensitive sites could approach minor
flood at times, mainly late tonight into early Thursday
morning, though west-of-south flow lowers confidence. More
notable water level decreases will occur Thursday behind a cold
front, before levels increase again by the weekend.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 7 AM EDT Thursday for ANZ530>533-
     538>542.
     Small Craft Advisory until 10 AM EDT Thursday for ANZ534-537-
     543.
     Small Craft Advisory until 4 AM EDT Thursday for ANZ535-536.

&&

$$

DISCUSSION...DHOF/KVH
AVIATION...DHOF/KVH
MARINE...DHOF/KVH
TIDES/COASTAL FLOODING...LWX

NWS LWX Office Area Forecast Discussion