Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

085
FXUS61 KLWX 212358
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
758 PM EDT Mon Sep 21 2026

.WHAT HAS CHANGED...
A line of moderate to heavy showers exits east of Chesapeake Bay
this evening with a few residual showers working back across
the southern Shenandoah Valley and northeast. Expect a brief
lull with more scattered to widespread rain overnight.

&&

.KEY MESSAGES...
- 1) Increased rain chances, cool temperatures, and abundant
  cloud cover continue through at least Thursday.

- 2) Dry conditions return later this week and into the weekend.

&&

.DISCUSSION...
KEY MESSAGE 1...Increased rain chances, cool temperatures, and abundant cloud
cover continue through at least Thursday.

Still monitoring what is left of a decaying MCV work across the area
this evening. A line of moderate to heavy showers continues to exit
east of the Chesapeake Bay over the next hour or so with just a few
showers and t-storms leftover the VA/WV Allegheny Highlands where
better instability resides. Expect any remnant t-storm activity to
settle down through 8pm with a lull into the front half of the
evening before more scattered to numerous pockets of showers/rain
develop overnight. Low pressure remains back toward eastern Ohio and
western PA with a stalled boundary sitting just south of the region.
Meanwhile, 1040 mb high pressure over eastern Quebec will continue
to strengthen heading into Tuesday and Wednesday. This will lead to
increased onshore flow and a persistent CAD wedge pattern heading
into midweek.

Large scale forcing for ascent will gradually increase from west to
east tonight into Tuesday as a shortwave trough and embedded upper
low approach from the Ohio Valley. As large scale forcing for ascent
increases, the coverage of showers will increase substantially
through tonight, and likely persist at times through Wednesday
morning. The precipitation may even resemble more of a continuous
stratiform rain shield as opposed to convective showers given the
stability overhead due in part to the CAD. Once again, the coverage
and timing of the heaviest rain will be hard to pinpoint given the
placement of the shortwave trough as it pivots through.

A few model solutions continue to produce several inches of rainfall
over localized areas (along/west of the Alleghenies) as we become
positioned in the right entrance region of a strong jet streak
developing off to our north and east, but there is lots of model to
model inconsistency as to if that will occur and where. As of now,
the most likely scenario appears to be for most of the region to
receive 1-2 inches of rainfall spread out over a prolonged period
time tonight through Wednesday morning. If this were to occur, the
rainfall would be beneficial in nature given the ongoing drought
conditions. However, if the solutions that produce isolated totals
of 3-6 inches were to play out, there could be localized issues with
flooding. Even if the solution with higher end totals plays out,
instantaneous rainfall rates won`t be overly high given the lack of
instability, so it would be more of a prolonged soaking rainfall
leading to areal flooding, as opposed to thunderstorms producing
flash flooding. As of now, no Flood Watches are planned, but we`ll
continue to monitor.

High confidence remains in regards to low clouds, breezy northeast
winds, periods of rain, and cool temperatures continuing through
Wednesday. Highs Tuesday will likely hold in the 60s Tuesday with
50s for highs by Wednesday as the CAD peaks. Thursday looks to be
the day of transition with high pressure nudging further south
allowing slightly drier air to push into the region. Shower chances
will likely continue, but should not be as widespread. Highs
Thursday will push back into the 60s.

KEY MESSAGE 2...Dry conditions return later this week and into
the weekend.

Surface high pressure builds northwest of the forecast area
beginning on Friday as a surface low pressure tracks northward off
the East Coast. Primarily dry conditions are expected, although
a nearby low pressure system brings increased precipitation
chances to the eastern portions of the forecast area.

Uncertainty remains on the track and timing of the low pressure
system, but recent guidance has it tracking north towards the
Northeast away from the Mid-Atlantic, possibly making a cyclonic
loop near Long Island. The most likely impact from the nearby
system will be increased winds due to the tight pressure
gradient overhead. North/northwest winds blow around 15-20 mph
Friday and Saturday before decreasing Sunday and into the workweek.

In addition to mainly dry conditions and gusty winds,
temperatures gradually warm each day. On Friday, highs will be
in the 60s for most (50s mtns) with overnight lows dipping into
the 40s and 50s. By the end of the weekend, high temperatures
will be in the 70s for most (60s mtns) with most staying in the
50s overnight.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
Ceilings will continue to drop this evening as onshore flow
increases with the strengthened high wedging in from the north,
stalled front nearby, and area of low pressure approaching from
the Ohio River Valley. As of 00z/8pm it`s a smattering of MVFR
to IFR cigs with LIFR cigs back towards the mountains. FOr now,
we remain in a lull with lingering showers over northeast MD and
the southern Shenandaoh Valley. Expect this lull through
2-4z/10pm-midnight with shower coverage likely increasing
overnight into Tuesday morning. IFR conditions will be the theme
of the valid TAF period and really through the middle of the
workweek as the onshore flow increases. Periods of light to
moderate showers will continue as well likely lingering through
at least Thursday morning as a series of low pressure systems
push through. Winds will remain out of the northeast through
Wednesday, and should gust to around 15-25 knots on Tuesday and
Wednesday. Gusts will begin to increase at the corridor
terminals prior to 9z/5am Tuesday morning as the gradient
tightens.

Northeast winds on Thursday shift to north/northwesterly on Friday,
gusting 15 to 20 knots each afternoon. On Friday, metro terminals
gust 20 to 25 knots. VFR conditions are expected both days under
dry conditions.

&&

.MARINE...
Expect a lull in the shower activity over the waters the next
few hours before an increase heading into early Tuesday morning.
Small Craft Advisories are now in effect with east to northeast
winds increasing heading into midweek. Gale Watches are in
effect for the waters around southern MD Wednesday into
Thursday. We`ll see if we need to expand or upgrade this watch
to a warning in the subsequent shift given better agreement
amongst the guidance potentially kicking in gale conditions as
early as Tuesday night over the aforementioned areas. Periods of
rain are also expected, which will reduce visibility.
Persistent onshore flow may result in waves as high as 3 to 6
feet in the wider waters of the Chesapeake Bay off southern
Maryland by mid week.

Northeast winds on Thursday blow 15 to 25 knots over the waters with
gusts up to 35 knots possible. A Gale Watch is in effect until
Thursday afternoon for the middle portions of the Chesapeake
Bay off southern Maryland. On Friday, north/northwest winds
blow 20 to 30 knots over the waters with gusts up to 35 knots
possible. Gale conditions are possible over the southern
portions of the waters with additional watches possible.

&&

.TIDES/COASTAL FLOODING...
Tides are expected to snap back to the north, with anomalies
rapidly rising again later tonight through the day Tuesday.
Elevated tide levels are then expected through much of the week
as a strong area of high pressure builds to our north, leading
to persistent onshore flow. The wind direction will be closer to
northeasterly rather than easterly, so the tidal levels are
expected to increase with southward extent in the Chesapeake
Bay. Many locations will likely reach Minor Flood Stage on
Tuesday and Wednesday, and Annapolis could come close to
flooding tonight as well. Moderate flooding can`t be ruled out
at some locations, especially at Annapolis by mid week. A
coastal low is expected to develop offshore later this week,
potentially prolonging coastal flood concerns.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory until 6 AM EDT Wednesday for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT Wednesday for ANZ530>543.
     Gale Watch from Wednesday morning through late Wednesday night
     for ANZ533-537-541-542.
     Gale Watch from Wednesday morning through Thursday afternoon
     for ANZ534-543.

&&

$$

DISCUSSION...DHOF/EST
AVIATION...DHOF/EST
MARINE...DHOF/EST