004
FXUS61 KLWX 241300
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
900 AM EDT Sun Aug 24 2025

.SYNOPSIS...
Shower and thunderstorm chances continue as the cold front
crosses the area this afternoon and evening. A strong dome of
Canadian high pressure builds thereafter with near to below
normal temperatures for much of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Early morning shower activity between I-81 and US-15 along a
subtle convergence axis around 850 hPa was showing signs of
weakening. Differential heating and perhaps a slight uptick in
near surface moisture left behind by these showers may serve as
a focus for redevelopment later today as a synoptic trough and
front move in from the west.

An upper low over southern Ontario will dig across the Great
Lakes and northern Mid-Atlantic pushing a strong cold front
through the area. Showers and thunderstorms are expected today
into tonight before the cold front moves eastward. SPC maintains
general thunder for the local FA today with no categorical
outlook (MRGL to the north). Cannot rule out a SVR storm or two,
but there is a disconnect between moisture, instability, and
forcing. Scattered storms should remain progressive limiting any
flood threat, although a few mergers are possible with locally
higher totals from the north-central Shenandoah Valley into the
central Virginia piedmont. WPC MRGL ERO is along/north of the
Mason-Dixon at this time.

Highs today will still be a tick or two below climo norms (low
to mid 80s for most with 70s in the mtns). Tonight, lows will
drop into the mid 60s ahead of the front with 50s behind the
front in the Alleghenies.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...
The cold front will exit the area early Monday after 06Z with
showers ending shortly thereafter. Expect a slight bump in winds
Monday as the front exits east and high pressure builds from
the Ohio River Valley. Gusts of 15 to 20 mph are possible out of
the north and northwest. Temps Monday will be below average
with 70s to near 80 for most. Areas AOA 3.5kft in the
Alleghenies likely don`t make it out of the 50s Monday - a sign
of what is to come later this week with a true Autumnal airmass
setting in. Lows Monday night will be in the 50s for most (60s
along the water and in the city centers). High elevation
valleys and bogs likely see the first frost of the season.

Broad H5 troughing will remain Tuesday across the eastern CONUS
with an area of Canadian sfc high pressure centered west of the
area. This will result in highs only making it into the 70s to
low 80s for most (upper 50s to 60s in mtns). Lows Tuesday night
will be the coldest since spring for most locales with temps
dropping into the 50s areawide (near 60 along waters and inner
cities). Another night of patchy frost is possible in the
favored locales.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...
At the beginning of the period, the broad H5 trough originating from
the Canadian Maritimes moves off the eastern US seaboard with
height rises on Wednesday, then steady heights before another
shortwave approaches from the northwest Friday. Generally, there
will be a troughy upper air pattern during the entire long term
period. But at the surface, high pressure moves in from the
Ohio Valley, and is directly overhead on Thursday morning. That
high moves off the Mid-Atlantic on Thursday, but is replaced by
circulation around a Canadian high pressure trekking across
Quebec Friday into Saturday.

H85 temps will generally be around 8-10C, but what will vary are the
sfc dwpts with chilly mornings both on Wed and Thu. Dry air at
the surface on these days may lead to morning temps in the upper
30s at the higher elevations of the Potomac Highlands, and
generally 5-10 degrees below normal across the CWA. Winds may
stay up on Tuesday night, inhibiting frost in the higher
elevations then, but with the high directly overhead on Thursday
morning, frost is possible.

24/01Z NBM is showing POPs AOB 10 percent through the long term
period. Other than the potential for frost in the higher
elevations Thursday morning, no impactful weather is expected.

&&

.AVIATION /12Z SUNDAY THROUGH THURSDAY/...
Prevailing VFR conditions are expected today, although
temporary drops to sub-VFR may be possible this afternoon as
scattered thunderstorms move through. Have maintained PROB30
groups to MRB, CHO, and IAD where confidence is greatest (may
still need to be expanded eastward with future forecast
updates). Winds will be out of the south today.

Winds turn of the west to northwest on Monday behind a cold
front while conditions remain VFR.

VFR conditions are expected for much of the week (Tuesday
through Friday) as Canadian high pressure settles over the
region.

&&

.MARINE...
A few gusts to 15 kts in southerly flow remain possible over the
wider waters of the bay. Otherwise, sub-SCA level winds are
expected today outside of marginal southerly channeling in the
early evening. SMWs may potentially be needed as
thunderstorms pass over the waters this afternoon/evening.

Come Monday night, winds may approach SCA levels as winds turn
northwest behind a cold front.

No marine hazards Tuesday through Thursday with winds northwest
10 to 15 knots.

&&

.TIDES/COASTAL FLOODING...
Water levels will be slow to recede until a cold front clears
the area Monday and winds shift to the NW. Widespread minor
coastal flooding will continue during this time.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Coastal Flood Advisory until 6 AM EDT Monday for MDZ011-014-
     018-508.
     Coastal Flood Advisory until 7 PM EDT this evening for MDZ016.
VA...Coastal Flood Advisory until 7 PM EDT this evening for VAZ054-
     057.
WV...None.
MARINE...None.

&&

$$

SYNOPSIS...DHOF/CPB
NEAR TERM...DHOF/CPB
SHORT TERM...DHOF/CPB
LONG TERM...Lee
AVIATION...DHOF/CPB
MARINE...DHOF/CPB
TIDES/COASTAL FLOODING...LWX