Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

261
FXUS61 KLWX 100125
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
925 PM EDT Sun Aug 9 2026

.WHAT HAS CHANGED...
We continue to monitor an ongoing MCS over Ohio. This MCS is
expected to weaken or entirely dissipate before making it into
our forecast area. See discussion below for more details.

&&

.KEY MESSAGES...
- Hot and humid conditions will persist through Thursday with
  daily of risk of showers and thunderstorms, some of which
  could be severe.

- Cooler conditions are expected for the end of the week,
  although showers and thunderstorms remain possible at times.

&&

.DISCUSSION...
KEY MESSAGE 1...Hot and humid conditions will persist through
Thursday with daily of risk of showers and thunderstorms, some
of which, could be severe.

As of 9 PM, a well organized MCS is ongoing across northwestern
portions of Ohio. Locally, a pocket of drier air remains in
place aloft, as shown by the 00z IAD sounding. This drier
profile limited the development of thunderstorms this afternoon
to Central Virginia. Deeper moisture is expected to gradually
return northeastward overnight into the day tomorrow ahead of a
shortwave disturbance and associated area of low pressure that
are forecast to pass well to our north. The aforementioned MCS
is expected to outrun the deeper moisture over the next few
hours, and eventually show signs of weakening as it works into
western PA and northern WV. Given the presence of a pretty well
established cold pool, it could potentially make it all the way
to the Allegheny Front after midnight in a much weakened state
before dissipating. Recent HRRR runs also indicate that some
additional development of thunderstorms may be possible late
tonight behind this MCS across western MD as deeper moisture
advects into the area from the southwest. If those storms were
to develop, they would likely be scattered in nature and
elevated, posing little threat for severe weather.

Another MCS is forecast to develop near the southern end of Lake
Michigan later tonight and then dive east-southeastward into
the Ohio Valley late tonight into tomorrow morning. Depending
on how this MCS evolves it could either maintain itself across
our forecast area tomorrow, or have its remnant outflow focus
the development of new convection tomorrow afternoon. If the MCS
were to totally fall apart before crossing the mountains, with
no remnant cold pool making it further east, the development of
thunderstorms across our area would be a bit more in question,
given only weak large scale forcing for ascent and questions
about where/if a lee trough would set up. What does appear clear
is that we should see strong daytime heating ahead of whatever
occurs, with the potential remnant outflow and disturbance aloft
moving through at peak heating. Before storms form, temperatures
are forecast to make it into the low to mid 90s, which when
combined with dewpoints in the lower 70s will make it feel like
around 100. In terms of timing, storms are expected to move
through from west to east between roughly 1 and 8 PM. Any storms
tomorrow should be capable of producing damaging wind gusts.
Previous discussion follows below...

A hot and humid air mass will persist over the mid-Atlantic
region between a subtropical ridge over the south central U.S.
and an active northern stream jet. As a result of this active
northern stream flow, numerous shortwave-troughs are fcst to
traverse the area during much of the work week keeping the risk
of daily showers and thunderstorms, some of which, could be
severe.

Tue and Wed look like the most active days of the week due to
stronger height falls and stronger mid-level flow with Tue
looking the day with greater instability and more enhanced
severe wx risk. As always, exact timing and location of severe
weather will depend on location`s of outflow boundaries from the
previous day.


KEY MESSAGE 2...Cooler conditions are expected for the end of the
week, although showers and thunderstorms remain possible at times.

The southward progress of the cold front becomes more uncertain
for the end of the week, although it likely drifts south with
time. Both physics-based and AI guidance shows lower severe
weather chances Thursday with declining instability. Showers and
thunderstorms could remain possible though with the front
nearby. For Friday and Saturday in particular, there may be a
better chance of drying out as high pressure builds to the
north. This will also bring a corresponding cool down in
temperatures (potentially a bit below normal) along with lower
humidity. The front won`t be too far to the south however, and
will likely attempt to lift north this weekend or early next
week as a low pressure system moves into the Great Lakes. Thus,
some low end PoPs remain in the forecast each day through the
end of the forecast period.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...
Fair weather tonight. Sct-nmrs afternoon and early evening
thunderstorms Mon-Wed with temporary flight restrictions
possible.

Relatively lower, but still existent, shower and thunderstorm
chances will continue Thursday and Friday (mainly afternoon/evening)
as a cold front gradually pushes south of the area.

&&

.MARINE...
Scattered mainly afternoon and evening thunderstorms which may
cause strong wind gusts. SMWs may be required Mon through Wed.

Wind speed and direction are a bit uncertain Thursday and Friday as
a cold front gradually pushes through the area. While winds appear
to be mostly sub-SCA at this time, there could be an enhanced
northwesterly surge once the front does push through. Afternoon and
evening thunderstorms remain possible until the front pushes south,
but the risk of strong/severe storms is lower compared to earlier in
the week.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$

DISCUSSION...ADS/LFR/KJP
AVIATION...ADS/LFR
MARINE...ADS/LFR