Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

386
FXUS61 KLWX 300759
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
359 AM EDT Wed Sep 30 2026

.WHAT HAS CHANGED...
Areas of stratocumulus are limiting fog development, but where
it stays clear, dense fog is possible. Much of the latest
guidance has shown a southward (drier) trend with a wave of low
pressure this weekend.

&&

.KEY MESSAGES...
- 1) After locally dense morning fog, temperatures will climb
  above normal today through Friday.

- 2) A cold front will bring rain showers and cooler
  temperatures to the area this weekend.

&&

.DISCUSSION...
KEY MESSAGE 1...After locally dense morning fog, temperatures
will climb above normal today through Friday.

Surface high pressure is nearly overhead this morning. The
residual mid/upper level trough axis is starting to depart,
which has allowed the more expansive stratus deck to steadily
shrink. However, some low level moisture still exists, and some
more clouds have filled in across the central Shenandoah Valley
and central Virginia. These clouds have been limiting fog
development, but have seen river valley and ground fog in areas
that are clear. It`s still a bit uncertain if fog can become
more widespread, but at least locally dense fog will be possible
through sunrise.

A shortwave ridge aloft will crest the area today while the
surface high starts moving off the coast. The ensuing southerly
flow will result in temperatures rising above normal, with highs
in the upper 70s and lower 80s expected for much of the area.
Stratocumulus clouds should scatter out through the day.
However, a shortwave passing through the Great Lakes will bring
increasing high level clouds later this afternoon into tonight.
Those clouds, combined with a light southwesterly flow, will
make any fog development much more localized tonight. Lows will
be in the upper 50s and lower 60s.

After the departure of the Great Lakes shortwave Thursday
morning, a large ridge will build over the southeastern CONUS.
Temperatures will rise further, with most of the lower
elevations in the 80s on Thursday, and perhaps even nearing 90
in a few spots. The ridge will break down on Friday as a trough
moves across the northern Great Lakes, but temperatures could
squeak a couple degrees higher. The exception will be west of
I-81 where clouds will be thickening, but it will still be a
very warm day.


KEY MESSAGE 2...A cold front will bring rain showers and cooler
temperatures to the area this weekend.

Upper-level troughing develops over the northern Plains before
tracking east late in the week, with a stemming cold front forming
ahead of it. Infused with tropical moisture from the Southwest, this
front will move into the Mid-Atlantic between late Friday and
Saturday before stalling to the south. Showers will become
likely along the Allegheny Mountains by Friday afternoon, but
there is some uncertainty how well the showers hold together
farther east moving into Friday night. As the front stalls,
additional rain showers will be possible throughout the
weekend, although timing and total QPF remains uncertain as
models deviate on where exactly the front will stall and the
development of a wave of low pressure. Many of the 00Z models
have shown a decidedly southern shift to the frontal zone, as
strong high pressure crossing the Great Lakes exerts influence.
Both the ECMWF and GFS AI ensembles still show relatively high
rain chances across the southern half of the CWA though, so the
coverage of rain is far from solidified. Regardless,
temperatures drop on Saturday in the wake of this front,
potentially failing to reach 70 degrees depending on the amount
of cloud cover.

A wave of low pressure to the north and trailing secondary cold
front will push the stalled front offshore by early next week,
with high pressure building behind the front as upper-level
zonal flow develops overhead. Conditions look to be much drier
during this period, with temperatures remaining cooler overall.
By Tuesday morning, temperatures over the mountains could
reach the 30s with perhaps some frost potential in the coldest
spots.


&&

.AVIATION /07Z WEDNESDAY THROUGH SUNDAY/...
Fog will be the main issue this morning, although its
development is hinging on several areas of (VFR) stratocumulus
clouds. Based on guidance available for the 06Z TAFs, CHO was
most likely to experience IFR conditions (and did very briefly
earlier), but clouds have now moved in there. That may leave
IAD, MRB, and perhaps BWI as the next best candidates for fog.

Surface high pressure will remain nearby today and Thursday
with VFR conditions expected both days. Southerly winds
generally less than 10 kt are expected both days. Fog is less
probable Thursday and Friday mornings.

An approaching cold front could bring some showers late Friday
afternoon and into the night, although they don`t appear
particularly heavy and ceilings may remain VFR. Lower CIGs are
possible at terminals Saturday and into Sunday as the front
stalls to the south. Intermittent rain showers Saturday night
and into Sunday could temporarily reduce VSBYs. However, these
impacts will be dependent on the frontal position, which has
trended south in recent guidance. Winds generally flow north to
northwesterly, with gusts between 15-20 knots possible during
then as the front tracks southeast.

&&

.MARINE...
Winds will become southerly today as high pressure drifts off
the coast. There could be a brief increase in winds this evening
on the wider waters of the middle Bay, but the potential for a
Small Craft Advisory is minimal. There may be a greater chance
of southerly channeling warranting an advisory Thursday night
into Friday.

A cold front will press southward Friday night, and the ensuing
northerly wind shift could result in advisory conditions. North
to northwest winds may remain within SCA thresholds on Saturday
in the wake of the cold front before diminishing some
overnight. Scattered showers are possible throughout the weekend
as the front moves through and potentially stalls for a bit,
but timing remains uncertain as model guidance still shows some
spread in where the front will linger.

&&

.TIDES/COASTAL FLOODING...
Some uncertainty continues to exist for the remainder of the
week as tide levels remain elevated and subtly fluctuating.
These small changes will make the difference in whether there is
additional minor flooding. Alexandria, Dahlgren, Annapolis, and
Havre de Grace have the greatest chance of reaching flood stage.
The evening high tides are favored for any flooding since they
are astronomically higher. A cold frontal passage should lead to
declining water levels Friday night.

&&

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

&&

$$

DISCUSSION...ADS/SRT
AVIATION...ADS/SRT
MARINE...ADS/SRT