289
FXUS61 KLWX 121449
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1049 AM EDT Sun Jul 12 2026

.WHAT HAS CHANGED...
No major changes were made to the forecast this morning. Showers
are starting to pop up and will continue to increase in coverage
as they drift off toward the south and west over the course of
the day.

&&

.KEY MESSAGES...
- 1) Showers and a few thunderstorms, will develop from eastern
  West Virginia to central Virginia today into tonight.

- 2) Increasing heat and humidity are expected during the middle
  of the week.

- 3) Strong to severe thunderstorms are possible by the end of
  the week.

&&

.DISCUSSION...
KEY MESSAGE 1...Showers and a few thunderstorms will develop
from eastern West Virginia to central Virginia today into
tonight.

As of 10 AM the front that moved through overnight has now
stalled out across northern NC and southwestern VA. Winds have
turned northeasterly to the north of the front. A warm, humid
airmass remains in place at low-levels, with surface dewpoints
still in the upper 60s and lower 70s. As high pressure builds to
our north over the course of the day, winds will turn from
northeasterly this morning, to easterly this afternoon, and then
southeasterly overnight. The 12z IAD sounding shows no
convective inhibition, and showers are already starting to pop
up across the region in response to daytime heating. These
showers are expected to increase in coverage and intensity
through the remainder of the morning and into the early
afternoon. Some of the showers will eventually intensify into
thunderstorms, with most models showing around 1000 J/kg of
MLCAPE by around peak heating this afternoon. While a stray
popup shower or storm can`t be ruled out anywhere, the highest
coverage is expected to remain to the south and west of the
Potomac River, and especially from the Central Shenandoah Valley
to Central Virginia.

The 12z IAD sounding shows near saturation up to about 650 hPa,
with drier air in the mid to upper levels of the atmosphere. In
contrast, the 12z RNK sounding shows near saturation all the way
through the depth of the troposphere. Model guidance also shows
this gradient in mid-upper level moisture from north to south
across the forecast area. Thus far, showers have progressed
from east to west within the low- level easterly flow. There is
a bit of west to northwesterly flow at higher levels of the
atmosphere, so if storms were to deepen, they may actually slow
down, with most model soundings and the 12z IAD sounding showing
LCL-EL mean winds of less than 5 kt. Deeper convection, and by
proxy slower storm motions, may become more favored to the
south (across Central Virginia and the Central Shenandoah
Valley), where the deeper moisture may promote storms growing
taller and tapping into the west to northwesterly flow aloft,
which would counter low-level easterlies and create slower
storms motions. The deeper moisture would also limit cold pool
development and associated propagation compared to storms
further to the north. With the aforementioned instability, slow
storm motions, and deep warm cloud layers (around 14k ft) heavy
rainfall should be the primary threat with storms today. There
could be an isolated instance or two of flash flooding from the
Central Shenandoah Valley to Central Virginia today, especially
if any storms are able to anchor to higher terrain in the light
easterly upslope flow. WPC currently has southwestern portions
of the forecast area outlooked in a Marginal Risk (level 1 of 4)
for excessive rainfall. Chances for showers and thunderstorms
should wind down later this evening with loss of daytime
heating. Primarily dry conditions are expected overnight.


KEY MESSAGE 2...Increasing heat and humidity are expected during the
middle of the week.

Upper high centered over the nation`s mid section early in the week
is expected to expand eastward Tuesday and Wednesday. More sunshine
will support highs on Tuesday warming into the upper 80s and lower
90s. At this time, Wednesday appears like the hottest day with mid
to perhaps upper 90s. While heat index values could top 100, it
won`t be as hot as it was during the first weekend of July.

The ridge may retreat westward toward the end of the week as an
upper level low drops into eastern Canada. The temperature forecast
remains a bit uncertain, but at least a couple more days in the 90s
are possible. A cold front could drop down from the north by the
end of the week.


KEY MESSAGE 3...Strong to severe thunderstorms are possible by the
end of the week.

Heights will fall in association with the eastern Canada closed low
during the second half of the week, and there will be moderate flow
aloft between this feature and the midcontinent ridge. In addition,
a cold front may drop south toward the area. With a hot and humid
airmass remaining south of the front, this will provide an
opportunity for thunderstorms (and possibly an MCS) to develop along
this corridor. Any such thunderstorms could be strong to severe with
damaging winds. However, confidence is very low given uncertainties
in the timing and placement of any forcing mechanisms. At this time,
the chances for thunderstorms are greatest Friday and Saturday.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
VFR conditions expected at the terminals today through Tuesday.
A couple of heavy showers and a thunderstorm near the CHO
terminal could briefly reduce conditions to MVFR this afternoon
and early evening. Winds will be out of the east today, then
southeast Monday and Tuesday.

VFR conditions are expected Wednesday and Thursday under high
pressure.

&&

.MARINE...
Winds will turn out of the east today. Small Craft Advisories
remain in effect for the Lower Tidal Potomac and our
southernmost Bay zones later this afternoon through much of
Monday night. Lighter winds are expected further north.

Great boating weather is expected Monday through mid week with
no thunderstorm potential. SCA conditions are likely Monday, but
winds will be diminishing by Monday evening.

With high pressure nearby, sub-advisory winds are currently expected
Wednesday and Thursday.

&&

.TIDES/COASTAL FLOODING...
Elevated water levels will persist for the next couple of days
with minor coastal flooding becoming increasingly likely Monday
into Tuesday as southerly flow strengthens.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory from 5 PM this afternoon to 4 AM EDT
     Monday for ANZ534-537-543.

&&

$$

DISCUSSION...ADS/AVS/KLW/KJP
AVIATION...ADS/KLW/KJP
MARINE...ADS/KLW/KJP

NWS LWX Office Area Forecast Discussion