Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

463
FXUS61 KLWX 161432
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
1032 AM EDT Sun Aug 16 2026

.WHAT HAS CHANGED...
We continue to monitor ongoing showers across the area this
morning, as well as additional rounds of showers and storms
developing upstream over the Ohio Valley. Multiple rounds of
showers and thunderstorms are expected across the area through
tonight.

&&

.KEY MESSAGES...
- 1) Severe weather and flash flooding are possible through
  tonight.

- 2) Thunderstorm chances return Wednesday night into Thursday.

&&

.DISCUSSION...
KEY MESSAGE 1...Severe weather and flash flooding are possible
through tonight.

Very active weather is expected over the next 12 to 24 hours,
with the threat for flash flooding, damaging wind gusts, and a
few tornadoes.

As of 10 AM, regional radar shows two well-defined MCVs. The
first is centered over southwestern PA, with ongoing showers to
the south and east across much of our forecast area. This
activity will continue to spread eastward over the next few
hours. A second MCV is located across northeastern Indiana and
northwestern Ohio. A few thunderstorms are already ongoing ahead
of this disturbance across Indiana and Ohio, and additional
storms are expected to pop up ahead of it this afternoon, and
then move in from the west this evening into the early overnight
hours. Questions still remain regarding how much development of
storms will occur in-between these two disturbances. As of now,
there is isolated activity developing across central Ohio in
the clearing between the two systems. Recent HRRR runs try to
have this activity dissipate before making it into our forecast
area, but that seems questionable given that there`s full sun in
place ahead of it, which should allow it to move into an
increasingly unstable environment. If this activity were to hold
together, it would likely make it to the Allegheny Front around
4 PM and then track eastward across the area through the
evening. The storms associated with the MCV in IN/OH currently
should reach the Alleghenies by around 8 PM, and then eventually
clear the bay by around 2 or 3 AM.

Trends will need to be very closely monitored given the very
high PW airmass and potential for repeat/training thunderstorms.
Should heavier thunderstorms train over any one area, 3 to 6
inches of rain would be possible on a localized basis. This
could cause scattered to numerous instances of flash flooding,
with considerable flash flooding possible in urban/poor drainage
areas or areas that have seen heavy rain recently. If and when
it becomes clearer where the greatest coverage of heavy rain
will set up, additional Flood Watches may be issued.

Regarding the severe weather threat, strong low-level winds
will boost SRH in a high moisture content environment. Wet
downbursts and brief spin ups would be possible in this
environment, with the tornado threat maximized along the slowly
lifting warm frontal zone - especially if any cell or cluster
interacts with/tracks along it. Shear is favorable for right-
moving (i.e. NW to SE) supercells if enough instability is
realized, and in those cases storms would be more apt to ingest
streamwise vorticity along the warm front (or residual outflow).

The wave this evening, though timed a bit after peak heating,
may pose the relative highest risk of damaging wind gusts due
to increased low-level flow orthogonal to what will probably a
linear type feature.

Convection (and corresponding severe/flood threats) may wane
only gradually tonight with continued low-level moist advection
beneath height falls aloft. This causes instability to remain
or even increase through the night.


KEY MESSAGE 2...Thunderstorm chances return Wednesday night into
Thursday.

As a cold front slowly moves across our area late Wednesday and
Thursday, shower and thunderstorm chances return across most of
our forecast region. Friday and Saturday, models continue to
depict a stalled front lying in our south, bringing sustained
chances for summer-time showers and thunderstorms. Currently,
it`s unclear if the position of synoptic features and
instability will be sufficient for hazardous weather. For now,
this will be a feature to monitor as the synoptic setup becomes
more defined. Temperatures may fluctuate a little depending on
what side of the front we`re on, but likely fall some by next
weekend, assuming the front pushes to the southeast.

&&

.AVIATION /14Z SUNDAY THROUGH THURSDAY/...
Active weather with multiple rounds of storms is expected
through tonight. The TAFs attempt to hone in on the highest
threat windows for TS with PROB30 groups at the moment, but
confidence is admittedly low with respect to timing, given the
potential for multiple rounds of storms. It should be noted
that, given the airmass in place, a shower or thunderstorm could
pop up at or near a TAF site at basically any time. Persistent,
backbuilding convection is also possible, which could prolong
restrictions if/when TS move near or over a TAF site.

South winds through tonight become northwest Monday. Gusts of 15
to 20 knots are possible this afternoon. A few storms could
contain gusts of 30-50 kts on an isolated basis through evening.

VFR is expected Monday into Tuesday as high pressure builds,
though a pop up shower or storm is possible Monday until a cold
front crosses by evening.

Potential showers and thunderstorms re-enter the forecast late
Wednesday.

&&

.MARINE...
Light southeast winds early this morning become south and
increase by late morning. Gusts of 15 to 25 knots are expected,
and Small Craft Advisories are in effect for all waters through
early this evening. Gusts likely taper somewhat over the middle
and upper tidal Potomac River, but persist elsewhere through
much of the night.

Thunderstorms become increasingly likely through the day, and a
few may produce wind gusts of 35 to 50 knots. The storm threat
could linger through the night, with even some chances Monday
prior to the passage of a cold front that will turn winds to the
northwest. Dry weather and light winds are expected Tuesday as
high pressure builds.

Winds turn southerly on Wednesday, and channeling may bring marginal
SCA conditions along the bay during the evening/overnight. A cold
front may bring some thunderstorms on Thursday.

&&

.TIDES/COASTAL FLOODING...
Southerly winds will increase water levels through tonight.
Vulnerable shoreline such as the Annapolis waterfront could
approach minor flood stage during high tide through the night.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 6 AM EDT Monday for MDZ008.
     Flood Watch until noon EDT today for MDZ501-502.
     Flood Watch through this evening for MDZ509-510.
VA...None.
WV...Flood Watch until noon EDT today for WVZ050-055-501>506.
MARINE...Small Craft Advisory until 6 AM EDT Monday for ANZ530>534-
     537>543.
     Small Craft Advisory until 8 PM EDT this evening for ANZ535-
     536.

&&

$$

DISCUSSION...DHOF/KJP/KVH
AVIATION...DHOF/KJP/KVH
MARINE...DHOF/KJP/KVH