799
FXUS61 KLWX 042339
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
739 PM EDT Thu Sep 4 2025

.SYNOPSIS...
A cold front will dissipate over the area tonight. Weak high
pressure will move across the area Friday. A stronger cold front
will reach the area Saturday. High pressure of Canadian origin
will build north of the area early next week.

&&

.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
As of 2330Z, showers and a couple thunderstorms continue across
southern and northeast MD. Given faster timing of showers
exiting, have updated POPs accordingly. Showers/thunderstorms will
continue to move off to the east through the evening.
Eventually, clearing aloft coupled with decreasing winds may
enable some patchy fog to form later tonight, especially to the
west of the Blue Ridge. Low temperatures overnight will be in
the upper 50s to the west of the Blue Ridge and 60s further
east.

&&

.SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/...
A deep upper low will continue to circulate over Western Ontario
tomorrow, but heights will rise locally as today`s disturbance
lifts off toward the north and east. Mostly sunny skies are
forecast, with highs in the mid to upper 80s for most.

Upper troughing will start to progress further southeast on
Saturday. This will lead to increasing winds and height falls
aloft, atop what will be an increasingly hot and humid airmass.
Morning sunshine should enable temperatures to climb into the
upper 80s and low 90s by peak heating. Dewpoints will also
increase into the 60s to near 70, making it feel more humid.
Thunderstorms are expected to form during the afternoon hours as
the system`s cold front moves into the area. Storms will form
within an environment characterized by around 2000 J/kg of
MLCAPE and around 40 knots of effective bulk shear. As a
result, any storms that form could turn severe, with both
supercells and bowing segments possible. Damaging winds will
likely be the primary threat, but an instance or two of hail
can`t be ruled out. Hodographs appear to be relatively straight,
so the threat for tornadoes looks to be low, if not non-
existent. SPC currently has much of the forecast area outlooked
in a Marginal Risk for severe thunderstorms.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
After a busy start to the weekend, conditions will markedly change
for Sunday. The secondary cold front is expected to be off the
Eastern Seaboard on Sunday morning while progressing offshore in
time. In its wake, an expansive dome of Canadian high pressure
settles over the Ohio Valley into the northeastern U.S. The current
guidance favors keeping this broad anticyclone near the region into
the middle of next week. This favors a return to below average
temperatures, low humidity, and dry weather.

Looking more closely at the synoptic pattern, a seasonably strong
longwave trough is forecast to cross through eastern North America
on Sunday into Monday. Characterized by height anomalies on the
order of 1 to 1.5 standard deviations below normal, this trough
swings off into the Canadian Maritimes by early next week. The flow
gradually begins to relax as heights build over the Southern/Central
Great Plains. However, longwave troughing does persist across much
of the northeastern U.S. into much of next week. Looking further
into the forecast, the Climate Prediction Center shows below average
temperatures/precipitation into next weekend as well.

Forecast high temperatures throughout the extended period will
mainly be in the low/mid 70s, with upper 50s to 60s in the
mountains. Northwesterly winds remain elevated which should
initially offset a more substantial nocturnal cooling event.
However, many nights next week will yield clearing skies and light
winds. As a result, forecast lows are in the upper 40s to 50s,
slightly cooler across the Shenandoah Valley. For the Allegheny
Front, spotty upper 30s to low 40s are not out of the question given
how dry the air mass will be.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Showers and storms will continue to move off to the east this
evening, with dry conditions expected overnight. Some MVFR
ceilings and/or patchy fog may be possible later tonight. MRB
and CHO will stand the greatest chance of seeing some fog.

VFR conditions and southerly winds are expected tomorrow.
Thunderstorms appear likely again Saturday afternoon. Some of
these storms could potentially be strong to severe. Outside of
storms, VFR conditions and southerly winds are expected.

VFR conditions are likely from Sunday through Tuesday. Behind a
potent secondary cold front, northwesterly winds will remain
elevated on Sunday. Afternoon gusts up to 15 to 20 knots are
possible before decaying into the evening/night. Expect winds to
turn lighter during subsequent days as a strong dome of high
pressure moves in from the Ohio Valley. As high pressure passes
nearby, winds turn northerly on Monday before shifting to east-
northeasterly by Tuesday.

&&

.MARINE...
SCA conditions should wind down from north to south later
tonight after the storms move through. Winds may near low-end
SCA levels in southerly flow on both Friday and Saturday as
well. SMWs appear likely on Saturday afternoon as storms move
over the waters.

Behind the secondary cold front, northerly winds should remain
rather breezy on Sunday. Small Craft Advisories will likely be
needed much of Sunday, perhaps into Sunday night. High pressure
continues to move in from the west on Monday. However, some residual
near-advisory gusts are possible on Monday morning before winds
decrease in strength.

&&

.TIDES/COASTAL FLOODING...
Tidal anomalies continue to increase within southerly flow.
Peak water anomalies appear to occur tonight ahead of an
approaching front. A Coastal Flood Warning is in effect for
Annapolis for the tide cycle tonight, and Coastal Flood
Advisories are in effect for many other locations. Water levels
may decrease a bit Friday as the first front fizzles out, but
minor flooding is still possible at a few locations Friday night
as southerly flow strengthens again ahead of the next front.
This front will bring a wind shift Saturday which will decrease
water levels.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 2 AM EDT Friday for MDZ008.
     Coastal Flood Advisory from 2 AM to 8 AM EDT Friday for MDZ011.
     Coastal Flood Warning from 11 PM this evening to 9 AM EDT
     Friday for MDZ014.
     Coastal Flood Advisory from 11 PM this evening to 4 AM EDT
     Friday for MDZ016.
     Coastal Flood Advisory until 4 AM EDT Friday for MDZ018.
     Coastal Flood Advisory from 6 AM to 11 AM EDT Friday for
     MDZ508.
VA...Coastal Flood Advisory from 11 PM this evening to 4 AM EDT
     Friday for VAZ057.
WV...None.
MARINE...Small Craft Advisory until 2 AM EDT Friday for ANZ530-535-536-
     538>541.
     Small Craft Advisory until 6 AM EDT Friday for ANZ531>534-537-
     542-543.

&&

$$

SYNOPSIS...KJP
NEAR TERM...KJP/CPB
SHORT TERM...KJP
LONG TERM...BRO
AVIATION...BRO/KJP/CPB
MARINE...BRO/KJP/CPB
TIDES/COASTAL FLOODING...LWX