729
FXUS61 KLWX 151816
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
216 PM EDT Tue Sep 15 2026

.WHAT HAS CHANGED...
No changes have been made to the forecast this afternoon.

&&

.KEY MESSAGES...
- 1) Remaining cool and dry through Wednesday.

- 2) Warmer with shower and thunderstorm chances increasing for
  the second half of the week.

- 3) Unsettled but uncertain pattern this weekend into early
  next week.

&&

.DISCUSSION...
KEY MESSAGE 1...Remaining cool and dry through Wednesday.

Abundant sunshine and very light southeast winds were being
observed as of mid afternoon with high pressure building across.

Light southeasterly gradients will favor an uptick in overnight
temperatures as high pressure drifts offshore. While still
cooler than recent days, most can anticipate lows in the mid 50s
to low 60s (mildest along the I-95 urban areas as well as near
the tidal Potomac River and Chesapeake Bay shorelines).


KEY MESSAGE 2...Warmer with shower and thunderstorm chances
increasing for the second half of the week.

Behind an exiting longwave trough that pushes into the Canadian
Maritimes, mid/upper heights begin to build in earnest on
Wednesday. An expansive near 600-dm mid-level ridge initially
over the southern U.S. will flex northward in time to a position
over the TN Valley by late Wednesday. These above average
heights remain a fixture in the forecast through Thursday. This
supports a return of warmer temperatures along with building
humidity levels. Daily highs push back into the mid/upper 80s,
locally reaching the low 90s in the warm spots. The return of
the humidity also favors milder nights with widespread lows in
the 60s.

Any shower and thunderstorm chances will be minimal for much of
the area through Wednesday. Thereafter, warm/moisture advection
coupled with terrain circulations and daytime heating could
result in a pop up shower as early as late Wednesday afternoon
near and west of the Appalachian crest. Low precipitation probs
expand slowly eastward in this WAA pattern Wednesday night into
Thursday morning, with some of the latest hi-res guidance even
bringing some activity just east of the Blue Ridge by daybreak
Thursday morning. Additional shower and thunderstorm chances
enter the picture Thursday afternoon and evening focused west of
I-95. With modest instability and generally weak shear, the
prospect for severe weather seems low, but it will be
unseasonably hot so some gusty storms can`t be ruled out.


KEY MESSAGE 3...Unsettled but uncertain pattern this weekend
into early next week.

A high latitude trough digging across southeastern Canada
should be enough to nudge the upper ridge back toward the south-
central U.S. by this weekend. This allows a cold front to push
through early Friday which again brings a gradual cool down with
decreasing humidity into Saturday. However, this reprieve is
somewhat brief and uncertain as additional disturbances in the
atmosphere track toward the area late in the weekend, causing
the front to waver back and forth near the region. The overall
jet pattern turns a bit more complex as an array of features
enter the picture. A broad upper low retrogrades across the
Gulf. At the same time, a myriad of shortwaves will eject across
the central U.S. toward the Mississippi Valley. How these
impulses behave along with where surface features reside will
dictate any local weather impacts. However, all signs point
toward a more active pattern by Sunday into early next week.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Canadian high pressure will support VFR conditions through mid-
week. Weak gradients keep lighter winds than yesterday/Monday,
with winds gradually shifting southeasterly through tonight.
This ridge eventually edges toward the Atlantic coastline which
will support mainly southerly winds on Wednesday into Thursday.
Some storm chances emerge by Thursday, but these may stay west
of most TAF sites.

A cold front moves through early Friday which results in some
uptick in shower chances. This may come with a few restrictions
if convection becomes more pronounced. In the wake of this
frontal passage, winds turn more northerly with afternoon gusts
to around 15 knots or so. High pressure building to the north
results in an east to southeasterly wind for Saturday. This
comes with likely VFR conditions.

&&

.MARINE...
As high pressure moves offshore, a brief and marginal period of
southeast gusts near SCA levels may develop around the upper
Chesapeake Bay from mid evening through 2 or 3am. Confidence is
currently too low in magnitude and frequency of gusts to issue a
Small Craft Advisory as of mid afternoon.

High pressure slowly pushes away toward the coast which results
in a south to southeasterly winds through Thursday. Some
southerly channeling effects may necessitate Small Craft
Advisories Wednesday afternoon and evening, and especially
Thursday afternoon and evening. A cold front tracks across the
waters on Friday morning which favors a shift to north to
northeasterly winds. These could near advisory criteria, but
confidence is low. High pressure passing by to the north will
result in a shift to east-southeasterlies for Saturday. Gusts
up to 15 to perhaps 20 knots are possible.

&&

.TIDES/COASTAL FLOODING...
Anomalies were gradually rising as of mid afternoon, with
further gradual rises expected through tonight before leveling
off as high pressure pulls away from the Eastern Seaboard. This
pushes a number of sites into Action stage during the higher of
the two astronomical high tides, particularly tonight and again
late Wednesday.

&&

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

&&

$$

DISCUSSION...AVS/BRO/DHOF
AVIATION...AVS/BRO/DHOF
MARINE...AVS/BRO/DHOF
TIDES/COASTAL FLOODING...BRO/DHOF

NWS LWX Office Area Forecast Discussion