Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

259
FXUS61 KLWX 270655
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
255 AM EDT Thu Aug 27 2026

.WHAT HAS CHANGED...
Added in the mention of an isolated tornado threat today, given
that SPC added a two percent tornado highlight to the latest
outlook.

Added some extra details in the aviation and marine sections.

&&

.KEY MESSAGES...
- 1) Severe thunderstorms are possible today as a frontal system
  collides with warm and humid conditions.

- 2) Turning drier this weekend, with increasingly hot and humid
  conditions for early/mid next week.

&&

.DISCUSSION...
KEY MESSAGE 1...Severe thunderstorms are possible Thursday amidst
increasingly warm and humid conditions.

Current surface analysis depicts a warm front still to our south
over the VA/NC border, as well as a cold front over the Ohio
Valley extending southward from the parent low in Quebec.
Aloft, latest satellite imagery depicts an influx of moisture
into the region this morning in response to a subtle jetlet
within the main trough axis. This is producing some showers to
our northeast of southeastern PA and into NJ as well. This
activity is building slowly southwest this morning, and is still
expected to build into northeast MD in the next several hours
leading up to sunrise.

More notable forcing arrives later today as the main upper
level trough and surface cold front approach from the northwest.
However, these forcing features may be somewhat displaced from
the local area during peak diurnal heating. The front will lag
to our northwest, while the strongest forcing with the trough
passes to the north. A secondary shortwave may approach but not
until the evening. Thus there remains some uncertainty in the
coverage and timing of any showers and thunderstorms, although
there is some model consensus on development along a surface
trough between the I-95 and I-81 corridors by mid afternoon.
Residual cloud cover and any leftover morning showers could put
a damper on instability. Then, especially for areas near and
east of I-95, convection may not arrive until after sunset, when
it could be weakening. However, if everything does come
together, moderate instability combined with deep-layer shear of
around 25-35 kt could result in some severe thunderstorms.
Damaging winds are the primary threat. Moderate mid level lapse
rates, strong winds in the upper atmosphere, and relatively
light low level winds could also result in some severe level
hail. As mentioned in previous forecasts, model guidance is
still depicting some decent low-level curvature to hodographs,
especially along the MD/PA border in northeast MD. The Storm
Prediction Center has actually added this area in to a two-
percent tornado threat today, which makes a lot of sense, should
things all come together. We will have to monitor heavy rain
potential as well, since relatively unidirectional flow relative
to the surface trough could result in some training (hinted at
by splotches of higher QPF in some CAMs). At the moment, this
threat appears higher to our north, and precipitable water
values and warm cloud depths are relatively modest. Thus no
Flood Watches are planned at this time. While some showers and
storms may linger into the night, the severe weather threat
should be winding down by mid to late evening.

The cold front may bisect the area by Friday morning while the
mid/upper level trough axis remains to the west. Some showers
and thunderstorms will continue to be possible near and south of
the front, although the risk for strong thunderstorms is lower.


KEY MESSAGE 2...Turning drier this weekend, with increasingly hot
and humid conditions for early/mid next week.

The late week cold front is expected to stall along the southeastern
U.S. coastline throughout the weekend. As this occurs, broad surface
high pressure is likely to extend from the southern Mid-Atlantic up
to New England. This configuration will support tranquil weather
this weekend with seasonable temperatures. Mid-level heights (585 to
589 dm) remain slightly above average which does keep temperatures
on the warmer side. Humidity levels drop a bit to start the weekend,
but do begin to come up some as winds shift to southerly on the back
side of the exiting surface ridge. This eventually sets up for a hot
and humid period into next week which also marks the conclusion of
Meteorological Summer (June 1-August 31).

A persistent mid/upper ridge across the southern tier of the country
is forecast to flex northward in time. Global ensembles generally
agree on this evolution, but vary with details along the northern
edge of this ridge. The net result will be another round of hot
temperatures along with increasing humidity. During the early to mid-
week period, forecast highs rise into the low/mid 90s, with heat
indices between 98 and 103 degrees. This could inch closer to the
105 degree heat index mark by Tuesday and Wednesday which is Heat
Advisory criteria for locations east of the Blue Ridge. Despite all
of the heat and humidity, daily thunderstorm chances could be more
limited if the area is underneath the upper ridge. However, these
details will likely become better resolved in a few days.

Looking a bit further ahead, the Day 6 to 10 outlook from the
Climate Prediction Center favors above average chances for continued
heat to linger into subsequent days.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
A warm front lifting north tonight may bring some isolated to
scattered showers and perhaps a thunderstorm later this morning,
particularly at BWI and MTN, hence the PROB30s there during
that timeframe.

A cold front will approach the region today and push through
tonight into Friday. A few strong to severe storms are possible
during the afternoon/evening, with gusty winds being the
primary threat. Starting to get a little bit more clarity on
timing for storms, so tried to hone in on the areas with highest
confidence (MRB, IAD, MTN, and BWI). Still PROB30s at DCA and
CHO. Storms could be slow to push through, so there may be some
prolonged period of restrictions for those that do get storms
today.

As the front stalls nearby tonight, some MVFR to IFR ceilings
or visibilities may develop. Current models seem to be favoring
fog, especially west of the metro areas. Showers and storms
could even redevelop Friday, but unsure if this would impact any
of the terminals (CHO would have the highest chance).

VFR conditions are expected Saturday through Monday Monday,
which comes with a dry forecast. Initial winds will be out of
the south before an eventual shift to westerly by early next
week. Relatively weak gradients should support peak gusts around
5 to 10 knots.

&&

.MARINE...
A Small Craft Advisory remains in effect through 6 AM for many
locations along the Chesapeake Bay due to southerly channeling.

Ahead of a cold front this afternoon, winds pick up out of the
south yet again, necessitating an SCA to be issued during this
forecast cycle. The front will also bring the risk of strong,
gusty thunderstorms, which would likely necessitate SMWs. Some
thunderstorms are even possible around sunrise in the northern
Bay zones, but the greatest risk for severe thunderstorms will
be during the late afternoon and evening.

Sub-small craft advisory level winds are expected on Friday as a
cold front moves in from the northwest. While some additional
thunderstorms are possible, the greater risk may be south of
Maryland. Sub-SCA level north to northeasterly winds are
forecast for Saturday, becoming southerly Sunday as high
pressure pushes to the east.

While devoid of any discernible convective activity, southerly
channeling effects could bring areas near Small Craft Advisory
criteria on Sunday evening into the early overnight period. Winds
shift to westerly by Monday with a gradual reduction in wind gusts.

&&

.TIDES/COASTAL FLOODING...
Increasing southerly flow continues through tonight, leading to
rising water levels. Most locations will only see action
stages, but Annapolis could approach minor flood stage early
Thursday morning. With the latest forecast only barely reaching
flood stage, will hold off on an advisory until confidence in
the water level trends increases.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...Small Craft Advisory until 6 AM EDT early this morning for
     ANZ531>534-537-539>541-543.
     Small Craft Advisory from noon today to 9 PM EDT this evening
     for ANZ531>534-537-539>541-543.

&&

$$

DISCUSSION...ADS/BRO/DHOF/CJL
AVIATION...ADS/BRO/DHOF/CJL
MARINE...ADS/BRO/DHOF/CJL