Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

925
FXUS61 KLWX 030803
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
403 AM EDT Thu Sep 3 2026

.WHAT HAS CHANGED...

No changes.

&&

.KEY MESSAGES...
- 1) Slight Risk of severe thunderstorms today and Friday.

- 2) Hot and humid conditions will persist through Friday.

- 3) Drier conditions expected for the Labor Day weekend ahead.

&&

.DISCUSSION...

KEY MESSAGE 1...Slight Risk of severe thunderstorms today and
Friday.

Multiple thunderstorm clusters will move from Pennsylvania east
southeast into northern.northeast Maryland today through
tonight along a frontal zone well defined on surface
observations and recent NUCAPS data. Given hot and unstable air
mass south of this frontal zone and moderately strong flow
aloft, thunderstorms will be capable of producing damaging wind
gusts. However, the forecast for today isn`t clear cut with
satellite imagery showing strong upper level ridging over much
of the area as per warm/dry water vapor signature on all three
GOES WV channels.

The signal for convection is much stronger for Friday than it is
for today with large scale height falls forecast, stronger low-
level convergence, and strengthening/stronger mid-level flow.
Believe the severe wx risk is greater tomorrow than it is today.


KEY MESSAGE 2...Hot and humid conditions will persist through
Friday.

Deterministing and ensemble trends indicate MaxT today will be
a couple of degrees hotter than yesterday, but show a spread of
2-3 degrees. Mid 90s seem likely and stayed away from any
guidance showing upper 90s. Without any appreciable change in
air mass, dewpoints should be in the low to mid 70s (72-73
degrees), which is what has been observed the past couple of
days and stayed away from any guidance that was showing 75-77
dewpoints. Plugging 94 over 73 dewpoints yields max heat indices
of 103.6F degrees. This is just shy of the heat advisory
criteria of 105, so heat indices of 100-105 is the most likely
range that we are going to experience today. Given the
uncertainty in the MaxT range, will not make any changes to the
Heat Advisory in effect. It will still be hot and humid
nonetheless. Similar heat indices are expected Friday.

KEY MESSAGE 3...

As the cold front from earlier in the week tracks south of the
region, surface high pressure begins to move across the Great Lakes
Saturday. Mid-level dry air settles over the Mid-Atlantic between
Saturday and Sunday, allowing for heat & humidity to drop through
the weekend. Highs for Sunday range in the low 80s across much of
the area, with dewpoints ranging in the 50s and low-60s. Overall, it
should feel relatively mild & dry over the Labor Day holiday.

Thunderstorm chances drop during this period as well with
increasingly stable conditions. Looking towards early next week,
upper-level ridging will begin to build over the Appalachians,
allowing for relatively dry conditions to continue as temperatures
start to increase again by Tuesday. Thunderstorm chances remain low
as this ridging builds overhead into next week.

&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...

MVFR/IFR cigs are expected this morning, then lifting quickly
after 14Z.

Numerous thunderstorms expected today and Fri, some of which,
could be severe with damaging winds. Exact timing remains
uncertain and will continue to handle TAFs with long PROB30
groups until things become clearer.

Prevailing VFR conditions are anticipated at terminals through
Sunday & Monday. Northeast winds shift southeasterly by Monday
evening.

&&

.MARINE...

SMWs may be needed again today especially north of the US-50
bridge and everywhere Friday.

Wind gusts stay below 15 knots between Sunday and Monday. Northeast
winds shift southeasterly by Monday evening.

&&

.CLIMATE...

A record daily high minimum of 73 degrees occurred at IAD
yesterday Wed Sep 02. This broke the old record of 72 degrees
set in 2020.

Record daily high maximums are not expected today or Friday as
records are in the upper 90s to low 100s. However, record daily
high minimums are still possible, but not likely, since
widespread convection is expected that should bring
temperatures close to their dewpoints.


&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Heat Advisory from 11 AM this morning to 7 PM EDT this evening
     for MDZ016>018.
VA...Heat Advisory from 11 AM this morning to 7 PM EDT this evening
     for VAZ029>031-036>040-050-051-055>057-501-502-526-527.
WV...Heat Advisory from 11 AM this morning to 7 PM EDT this evening
     for WVZ053.
MARINE...None.

&&

$$

DISCUSSION...LFR/SRT
AVIATION...LFR/SRT
MARINE...LFR/SRT