562
FXUS61 KLWX 160130
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
930 PM EDT Tue Jul 15 2025

.SYNOPSIS...
A frontal boundary will remain nearly stationary over the region
today before dissipating by Wednesday morning. Another cold
front moves through the region late Friday before stalling
nearby through the weekend, possibly into early next week.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
As of 9 PM, there area still a few clusters of slow moving
thunderstorms along the Allegheny Front and east of the central
Virginia Blue Ridge. Other isolated showers are located south of
DC toward southern Maryland. A Flood Watch for flash flooding
remains in effect until midnight toward central Virginia, and
was earlier expanded by a row of counties to the north. These
slow moving storms have been producing localized totals over 2
inches, and slowly expanding north, likely along outflows and
terrain convergence. The combination of the loss of daytime
heating, and drier mid level air and less convergence to the
north, should allow the storms to gradually fade, though it`s
not out of the question some isolated showers may continue
northward. After midnight, any lingering activity should be
isolated and lighter in nature.

Heading into the overnight, a mild and humid air mass persists
with forecast lows in the upper 60s to mid 70s. Light winds
combined with saturation of the low levels will support patchy
fog, some locally dense. Areas that have seen heavy rainfall
and the more vulnerable low-lying river valleys have the best
shot at dense fog. Mid/high level clouds could be a mitigating
factor.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
As the upper ridge departs to the east, heights again lower on
Wednesday in response to a combination of shortwaves and
convective-induced perturbations. The energetics aloft will
again move into the very moist and unstable environment across
the Mid-Atlantic states. A preponderance of 12Z high-resolution
models favor semi-robust convection across the region on
Wednesday afternoon and evening. Not surprisingly, the placement
of convective maxima vary from model to model, but the signal is
certainly present. Area-wide precipitable water values return to
the 2 to 2.25 inch range which is up around the 95th percentile
and above for mid-July. This combination of identifiable forcing
mechanisms with anomalous tropical moisture will enhance the
risk of flash flooding on Wednesday. The Weather Prediction
Center has upgraded much of the area into a Slight Risk for
excessive rainfall. Flood Watches will likely be needed at some
point given Wednesday`s setup.

Severe weather is not completely out of the question either as
the Storm Prediction Center has raised the risk area to a
Marginal across much of the region. Taller thunderstorms will
be capable of carrying water-loaded downdrafts to the surface
which would bring a threat of damaging wind gusts. Any
convective threats should wane after dark given the loss of
diabatic heating.

On the temperature side, expect another typical summertime day
with highs rising into the upper 80s to low 90s. Adding the
persistent humidity in the air will carry heat indices to around
97 to 102 degrees. The only relief would come in the scattered
to numerous thunderstorms across the region. Warm and humid
conditions again persist into the night with low temperatures in
the low/mid 70s. Like previous nights, patchy fog may develop
across the region.

Moving into Thursday, the local area appears to be in between
systems which should yield a reduced threat of convection.
However, temperatures do spike further with high temperatures
pushing into the 90 to 95 degree range. Adding the persistent
high dew points carries heat indices to around 100 to 105
degrees. This would near Heat Advisory thresholds so this bears
some watching. Little to no relief is expected into the night
with Thursday night`s low temperatures well into the 70s (mid
60s to low 70s for mountain locales).

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
The longwave pattern across the CONUS should remain fairly
consistent through the long term period, with zonal flow across the
northern tier of states and subtropical ridging in place over the
south. Multiple disturbances will pass to our north within zonal
flow during the long term period. This will keep conditions active,
with daily chances for showers and thunderstorms across the
area. Temperatures will remain near average, with highs in the upper
80s to around 90, and lows in the upper 60s and lower 70s.

While an instance or two of damaging winds or flash flooding can`t
be ruled out any day, Friday appears to be the day with the greatest
chance for damaging winds or flash flooding. A cold front will
approach from the north and west that day as deep moisture pools
ahead of the front and mid-level flow increases to around 25-30
knots.

&&

.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
A thunderstorm is gradually diminishing near CHO. An isolated
shower has popped up SW of DCA, though it appears direct impacts
to the metro terminals from thunderstorms appears unlikely this
evening. Otherwise, winds remain on the lighter side with some
restrictions possible heading into the overnight hours. Patchy
fog is most likely across CHO and MRB, with brief IFR possible
(not included in TAF yet due to uncertainty). Some guidance also
indicates low ceilings may develop toward sunrise and persist
for part of the morning, especially east of the Blue Ridge.

Wednesday is looking fairly active across the area with the
potential for afternoon/evening thunderstorms at all terminals.
Timed a 4 hour TEMPO group for the most likely period of
thunderstorm impacts. Otherwise, southerly winds increase
through the day with possible gusts up to 15 knots. Like
previous nights, patchy fog may develop Wednesday night.
Convective chances decrease on Thursday, but cannot rule out
brief restrictions as air mass thunderstorms pop up.

Prevailing VFR conditions are expected on both Friday and Saturday.
A thunderstorm could lead to brief restrictions either afternoon or
evening. Winds will generally be out of the northwest on Friday, and
out of the south on Saturday.

&&

.MARINE...
Sub-advisory caliber winds remain through Wednesday given weak
gradients. However, a ramp up is eventually expected during the
Wednesday evening into Thursday. The uptick in southerly winds
may lead to some localized channeling effects, particularly
across the southern-most waters. Small Craft Advisories may be
needed from Wednesday evening into portions of Thursday as gusts
rise to 20 to perhaps 25 knots.

A threat for convection on Wednesday will lead to some hazardous
marine conditions, particularly during the afternoon/evening
hours. Special Marine Warnings may be needed for any of the
stronger storms. Convective chances decrease into Thursday, but
some isolated to scattered storms may fire up during peak
heating.

Sub-SCA level winds are expected on both Friday and Saturday. Winds
will generally be out of the northwest on Friday, and out of the
south on Saturday.

&&

.TIDES/COASTAL FLOODING...
After a brief lull in the warm advection flow regime, expect a
return to the prolonged period of southeasterly winds. This will
lead to elevated tidal anomalies through midweek, particularly
across Annapolis. This location will see Action stage at
times, particularly during the higher of the two astronomical
high tide cycles. However, outside of freshwater influences from
heavy rainfall, the threat for tidal flooding appears low.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...Flood Watch until midnight EDT tonight for VAZ025-026-036>038-
     050-056-507-508.
WV...None.
MARINE...None.

&&

$$

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