McLean, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

119
FXUS61 KLWX 110600
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
200 AM EDT Mon Aug 11 2025

.SYNOPSIS...
Warm temperatures, mostly dry conditions, and low humidity look to
continue through Tuesday as broad high pressure remains nearby.  A
frontal system may gradually approach from the west Wednesday into
Thursday as the high moves out to sea. This will result in increasing
heat and humidity as well as thunderstorm chances across the region
later in the workweek and into the upcoming weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
High pressure off the Northeast and Mid-Atlantic coast will
continue an eastward drift out to sea today. Return flow around
the departing high will result in an increase in heat and
humidity. A low overcast may persist east of the Blue Ridge this
morning in light onshore flow, but should disperse resulting in
a partly to mostly sunny afternoon. With the increase in heat
and humidity and a bit of a breakdown to the ridging aloft will
come the potential for a pop up shower or thunderstorm or two.
This potential is highest furthest from the departing ridge,
generally from southern MD across the central VA piedmont into
the central Shenandoah Valley.

Another round of low clouds and patchy fog is possible in
continued onshore flow tonight. It will be noticeably more humid
with low temperatures in the 60s to lower 70s.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...
Heat and humidity will continue to increase Tuesday into
Wednesday. Shower and thunderstorm chances are a bit higher
Tuesday afternoon and extend a bit further north and east when
compared to Monday, but lingering ridging should keep coverage
scattered. High temperatures will likely eclipse 90 for much of
the area, and when combined with dew points around 70 could
result in heat index values of 95-100. More expansive storm
probabilities are noted on Wednesday as an upper trough swings
by to the northwest and its associated surface cold front drifts
toward the area. Wednesday currently looks like the hottest day
of the upcoming week - generally lower 90s with heat index
values around or a little over 100 (though some of this could be
muted by shower and thunderstorm activity).

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...
A summertime pattern persists through the period with heat,
humidity, and daily chances for showers and thunderstorms in the
forecast. On Thursday, a rather potent longwave trough crosses
through Quebec while the attendant height falls graze the
northeastern U.S. In the wake, global ensembles show a subtropical
ridge across the southeastern U.S. strengthening and expanding in
time. 500-mb heights push back into the 589-592 dm range as the
influence of northern stream disturbances wanes. While the initial
longwave trough carries a cold front on the doorstep of the local
area, the boundary should stall nearby on Friday before completely
shearing out over the weekend.

Daily high temperatures should push into the mid 80s to low 90s,
with mountain locales seeing mainly 70s to low 80s. Given the return
of the humidity, overnight lows will not plunge the way they have
been over the past week or so. Expect most to fall into the upper
60s to low 70s, with some low/mid 60s across the mountains. The best
chance for showers and thunderstorms would be Thursday and Friday
with the cold front stalling nearby. Thereafter, the further
building of heights and lack of any frontal zones leads to
decreasing convective chances for the weekend. However, in these
scenarios, mesoscale boundaries like bay/river breezes and terrain
circulations can act as a focus for some afternoon/evening
convection.

The Climate Prediction Center outlook into next week favors a
continued summertime pattern with above average temperatures being
favored.

&&

.AVIATION /06Z MONDAY THROUGH FRIDAY/...
Most guidance is in general agreement with low clouds banking up
against/east of the Blue Ridge this morning from roughly
daybreak through late morning or midday. Given the only recent
increase in low-level moisture, I`m unsure ceilings will get
quite as low as some of the more aggressive guidance like the
NAMNest and GLAMP show, but generally speaking IFR seems likely
for a time developing around 09z-10z around KCHO and spreading
quickly NE. CIGs should lift/scatter by 14z-17z. A pop up shower
or thunderstorm can`t be ruled out this afternoon near KCHO.
S/SE flow AOB 10 kts is expected.

Low clouds and/or fog appear likely again late tonight into
Tuesday morning, with a bit higher chances for PM TS mainly near
KCHO and KMRB Tuesday afternoon. More numerous TS are possible
Wednesday afternoon. Winds will be S/SW AOB 10 kts.

With a frontal zone nearby, there will be a risk of daily
afternoon/evening showers and thunderstorms Thu/Fri. Thus, some
restrictions cannot be ruled out at times across all terminals.
Gradients remain on the weaker side with mainly northwesterly
winds for Thursday before turning more easterly by Friday.
However, such winds will largely be dependent on the position of
the front and other convective processes.

&&

.MARINE...
Light south to southeast winds are expected through Tuesday,
gradually becoming more southwest by Wednesday. A pop up shower
or thunderstorm along the bay breeze is possible Tuesday
afternoon, with higher chances Wednesday afternoon. Some
marginal southerly channeling may approach SCA levels Tuesday
evening, but otherwise sub-SCA conditions are most likely.

While background wind fields should mainly keep gusts around 10
knots or less on Thursday and Friday, the risk of afternoon/evening
convection may bring hazardous conditions to the waters. Initial
winds will be out of the northwest before turning more light and
variable into Friday.

&&

.TIDES/COASTAL FLOODING...
Elevated tidal anomalies look to continue through Tuesday given
the recent full moon and light onshore flow. Near minor tidal
flooding is possible with high astronomical tides (especially at
Annapolis and perhaps Dahlgren/Alexandria).

&&

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

&&

$$

SYNOPSIS...DHOF/EST
NEAR TERM...DHOF
SHORT TERM...DHOF
LONG TERM...BRO
AVIATION...BRO/DHOF
MARINE...BRO/DHOF
TIDES/COASTAL FLOODING...LWX