134
FXUS61 KLWX 030807 CCA
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Wed Sep 3 2025

.SYNOPSIS...
High pressure will progress offshore today. A cold front
will approach the area from the west on Thursday. A stronger
cold front will move through on Saturday. High pressure will
build back in early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Surface high pressure extends along the eastern seaboard this
morning. A weakening low aloft is lifting into Quebec while
additional shortwave troughs are located across the Ohio and
Tennessee Valleys. Mostly clear skies prevail, although some
high clouds are approaching from the southwest and mid level
clouds are located just to the east. So far fog has been very
patchy based on observations, but some additional fog could form
in low lying spots through sunrise.

With wind direction shifting to southerly today, temperatures
and dew points will start to increase a bit. Highs will reach
the mid 70s to lower 80s, and only the highest elevations will
remain in the 60s. A mix of clouds and sun is expected as the
shortwave approaches from the southwest. A few showers and
perhaps a thunderstorm could develop along the Allegheny
Highlands, but instability is weak and decreases further east
of the Blue Ridge, so don`t expect convection to have much
longevity.

Wind fields begin to increase tonight as the shortwave crosses
and the surface pressure gradient starts to tighten ahead of a
cold front moving through the Great Lakes. While the surface
will decouple to an extent, this change in pattern will result
in warmer temperatures, with lows only dropping to the mid 50s
to mid 60s. The light wind may help prevent fog formation,
though some guidance indicates some low clouds or fog may
develop near the Chesapeake Bay.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
An anomalous closed low will be approaching the upper Great Lakes
Thursday, while some shortwaves/vorticity lobes rotate out ahead
of it. An associated cold front will be moving through the Ohio
Valley during the morning hours. Some weak convection could
approach the Appalachians fairly early in the day. Some guidance
shows this activity, or its remnant perturbation, being the
impetus for additional convective development across the area
Thursday afternoon and possibly into the evening. Additional
convection may fire closer to the surface front, but will likely
weaken as it moves into the Appalachians during the evening.
Instability will be modest, likely less than 1000 J/kg, but deep
layer shear will be 35-40 kt with a relatively straight
hodograph. Thus some linear segments, or even a splitting
supercell or two, could develop. A Marginal Risk for severe
thunderstorms remains in place across much of the forecast area,
with a primary threat of damaging winds. Activity may tend to
weaken toward the Interstate 95 corridor if it is not very
organized, as instability is forecast to be weaker, and mid
level forcing will be pivoting away to the northeast. There will
likely be gaps in the coverage, and storms should be
progressive, so this likely won`t be a remedy to recent dry
weather. Gusty south winds will push temperatures into the
lower to mid 80s before precipitation arrives.

The front essentially washes out as it moves into the area
Thursday night, with very little change in airmass or wind
direction. In fact, as high pressure is reestablished by Friday,
temperatures will be even warmer in the mid to upper 80s. A few
showers could reach the Allegheny Front Friday night as the next
frontal system approaches, but most locations will remain dry
and mild.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
Strong upper level trough pivoting through the region Saturday night
will push a strong cold front across the area Saturday. Showers and
thunderstorms are expected, some possibly severe Saturday afternoon
until strong cdfnt clears the area Saturday evening. Will likely see
a sharp drop in temperatures with this front. Canadian high pressure
then builds into the area through Monday supporting cool and dry
conditions. Temperatures will be more typical of late Sep than early
Sep. A wedge sfc pattern develops across the area through the
remainder of next week keeping fair and cool conditions.

&&

.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
High pressure remains in place this morning. Some patchy fog is
developing, so can`t rule out a brief period of reduced
visibility at CHO and MRB. VFR conditions with light south winds
will prevail today and tonight. The chance for fog is lower
tonight as a light south wind should remain in place, but some
guidance hints some low clouds may form near BWI and MTN.

South winds will gust to around 20 kt Thursday as a cold front
approaches. Showers and thunderstorms are possible during the
afternoon and evening, although coverage may be scattered,
especially toward the metro terminals. However, any stronger
thunderstorm clusters could contain gusty winds.

At this time, there aren`t any strong signals for significant
weather late Thursday night through Friday night as the front
fizzles out and southerly flow remains in place.

Showers and thunderstorms are likely Saturday into Saturday
evening.

&&

.MARINE...
Variable sub-SCA level winds are occurring this morning. By late
morning, the prevailing direction will become southerly and
gradually pick up in magnitude by tonight, especially along the
bay. At this time, the greatest chance for channeled gusts to
near 20 kt appears to be between Pooles Island and Drum Point, where
an advisory has been issued.Winds will increase across all waters
after sunrise Thursday, with advisories likely needed. Some
thunderstorms with gusty winds could reach the waters later Thursday
afternoon or evening.

Winds may decrease for a time late Thursday night into Friday
morning as the front fizzles out, but additional advisories
will likely be needed later Friday into Friday night while
southerly flow remains in place.

SCA conditions are likely Saturday into early next week both in the
pre-frontal and post-frontal environment. Strong t-storms Saturday
afternoon may also require SMWs.

&&

.TIDES/COASTAL FLOODING...
Water levels are starting to increase a bit this morning. As
southerly flow develops and strengthens today and tonight,
further rises in water levels are forecast. Confidence in
Annapolis reaching minor flood increases tonight. Peak water
anomalies appear to occur Thursday night ahead of a front in
strong southerly flow. More locations may reach minor flood, and
some guidance has Annapolis approaching moderate flood. Water
levels may decrease a bit Friday as the first front fizzles out,
but minor flooding may still occur at Annapolis 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...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from midnight tonight to 8 AM EDT
     Thursday for ANZ531>533.

&&

$$

SYNOPSIS...ADS
NEAR TERM...ADS
SHORT TERM...ADS
LONG TERM...LFR
AVIATION...ADS/LFR
MARINE...ADS/LFR
TIDES/COASTAL FLOODING...ADS