Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

793
FXUS61 KLWX 040800
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Sat Jul 4 2026

.WHAT HAS CHANGED...

Given an uptick in today`s heat index forecast, have upgraded
to Extreme Heat Warnings across north-central Maryland down
across the eastern West Virginia Panhandle into the Shenandoah
Valley. For today`s convective threat, the Storm Prediction
Center has upgraded to an Enhanced Risk for severe thunderstorms
across locations east of the Blue Ridge Mountains.

&&

.KEY MESSAGES...
- 1) A highly impactful Independence Day lies ahead today with
  extreme heat and an Enhanced Risk for severe thunderstorms.

- 2) Severe thunderstorm chances continue Sunday and Monday
  along with and increased risk for flash flooding.

- 3) More seasonable conditions return by mid/late next week.

&&

.DISCUSSION...
KEY MESSAGE 1...A highly impactful Independence Day lies ahead
today with extreme heat and an Enhanced Risk for severe
thunderstorms.

Anomalous heat and humidity remain a fixture across the area.
Based on the latest 07Z/3 AM observational data, temperatures
generally range from the mid 70s to mid 80s. This is accompanied
by dew points in the 70s which is yielding overnight heat
indices between 85 to 95 degrees. Skies remain mostly clear
although there is still residual convective debris drifting
southward from central Pennsylvania.

Before convection enters the picture, it will be another day of
record warmth across the Mid-Atlantic region. Using 850-mb
temperatures as a proxy, forecast readings should be around
22-23C which dry adiabatic mixing favors another 100 degree day.
Adding continued tropical moisture in place will support heat
indices pushing into the 105 to 110 degree range. Extreme Heat
Warnings are in effect from 10 AM until 9 PM for areas east of
the Blue Ridge. Given an uptick in forecast heat indices, have
upgraded to warnings over north-central Maryland down across
the eastern West Virginia Panhandle into portions of the
Shenandoah Valley. Otherwise, outside of mountain locations,
Heat Advisories will be in effect until 8 PM this evening.

Unlike previous days which were free of convection, a collapsing
ridge will lift the subsidence that has persisted the last few
days. Although mid/upper heights remain anomalous in nature,
forcing from an approaching shortwave will aid in more
widespread showers and thunderstorms. One unique aspect to the
thermodynamic environment is an elevated mixed layer (EML) which
has shown up in the last 4 IAD sounding profiles. Within this
layer around 750-600 mb, lapse rates continue to run between 8-9
C/km which is unusually steep for this area. This is
contributing to some impressively large amounts of instability,
generally in the 3,000 to 4,000 J/kg. Within the deeply mixed
boundary layer, substantial downdraft CAPE (DCAPE) is evident
with values around 1,300 to 1,700 J/kg. Although vertical shear
is only around 20 to 25 knots, any storms able to tap into the
robust instability will be capable of damaging winds. Some of
this could be locally destructive with gusts up to 60 to 75 mph.

With all of the above in mind, and ample high-resolution model
support, the Storm Prediction Center has upgraded areas east of
the Blue Ridge to an Enhanced Risk today. This upgrade would
support a more widespread footprint of severe thunderstorms this
afternoon and evening. Looking a bit more closely at today`s
setup, convective initiation likely will be more mesoscale in
nature. This would include the climatological lee-side trough,
bay and river breezes, as well as any remnant outflows from
earlier convection. Multiple rounds of thunderstorms are
possible given so much instability in the troposphere. The
primary signal east of the Blue Ridge is in the 3-9 PM
timeframe, slightly earlier to the west. Damaging to locally
destructive winds are the main threat, with any chance for large
hail being minimal given the summertime freezing levels.

Although the convective signal is strongest during the afternoon
to early evening hours, residual storms could easily impact
those with outdoor plans for fireworks this evening. Continue to
check back at weather.gov/lwx or follow the National Weather
Service - Baltimore/Washington social media accounts for the
latest.


KEY MESSAGE 2...Severe thunderstorm chances continue Sunday and
Monday along with and increased risk for flash flooding.

To finish out the holiday weekend, an active weather pattern
likely continues into the start of the new work week. Behind the
earlier shortwave trough, residual lower heights will approach
from the Ohio Valley on Sunday into Monday. This carries a
parent frontal system into the Mid-Atlantic region which may be
slow moving or even quasi-stationary at times. Until this system
exits the area to the south, unsettled conditions will remain in
the picture.

While a bit cooler than recent days, it will be another
seasonably hot and humid day across the area. High temperatures
should fall short of the century mark, but heat indices are
likely to range from the 100 to 105 degrees, locally a bit
higher south of I-66. Additional Heat Advisories might be needed
if these elevated heat indices persist in subsequent forecast
packages. Ample cloud cover and shower/thunderstorm activity may
hinder surface heating in spots. Otherwise, convection looks
widespread again with a Slight Risk for severe weather east of
the Alleghenies (Marginal Risk over these mountains). If similar
thermodynamic profiles continue into Sunday, damaging winds
would be primary threat with the stronger cells.

An additional aspect to the Sunday into Monday forecast is the
flash flooding threat. With multiple rounds of showers and
thunderstorms expected from today/Saturday into early next week,
excessive rainfall may occur across portions of the area.
Precipitable water (PWAT) values remain quite anomalous in
nature, generally averaging between 1.75 and 2.25 inches. Adding
this tropical laden moisture with a near stalled frontal system
will aid in a discernible flood threat. Due to the flashy
nature of the metro areas, these would be the most vulernable to
any rapid hydrologic response. Although the area remains in a
longstanding drought, rapid run-off can still occur in these
high PWAT environments. Consequently, the Weather Prediction
Center is maintaining a Slight Risk for excessive rainfall on
Sunday into Monday night.


KEY MESSAGE 3...More seasonabl conditions return by mid/late
next week.

Persistent troughing to start the week will gradually see these
lower heights pull away from the Atlantic coast. The resultant
reflection at the surface would carry the surface cold front
down into the Carolinas by mid-week. As this boundary settles
to the south, a more seasonable air mass takes over the Mid-
Atlantic states. Daily high temperatures will be in the mid 80s
to low 90s, with overnight lows in the mid 60s to low 70s. For
mountain locales, expect these readings to be around 5 to 10
degrees cooler. However, this comes with some temperature spread
as evident in ensemble box-and-whisker plots. Additionally, there
should be some diurnal convection at times during this mid/late
week period, but details are more difficult to discern this far
out in time.

&&

.AVIATION /06Z SATURDAY THROUGH WEDNESDAY/...
While VFR conditions are currently in place at all terminals, a
more active weather pattern begins to impact the region later
today. Numerous showers and thunderstorms are expected to break
out this afternoon and evening, many of which will be strong to
severe in nature. The most likely timeframe from impacts would
be around 18-23Z for the more western terminals to 20-01Z around
the Baltimore TAF sites. PROB30 groups are being advertised at
this time for this threat. Additional restrictions are certainly
possible outside this window given the continued threat for
showers. Otherwise, for today, winds stay on the lighter side
while shifting from northwesterly over to west-southwesterly.
Some low-level wind shear is possible in the 03-09Z window
tonight as a southwesterly jet tracks through.

Looking ahead to Sunday and Monday, a nearby frontal system will
make for more widespread convection. This supports more periods
of restrictions, particularly for the afternoon to evening
hours. Given the amount of rainfall expected through Monday,
some nighttime patchy fog cannot be ruled out. Winds on Sunday
into Monday begin out of the southeast before turning more
easterly into the new work week.

On Tuesday into Wednesday, mainly VFR conditions are expected in
the wake of the exiting cold front. Winds will be out of the
north to northeast behind this boundary. Some diurnal convection
may occur, but restrictions are looking less likely at this
time.

&&

.MARINE...
Overall synoptic gradients are on the weaker side given the time
of year. There could be a few surges up the Chesapeake Bay at
times, but confidence is low if these will be strong enough to
cause any Small Craft Advisories. The bigger issue for the
waterways will be a multi-day period of strong to severe
thunderstorms. For today, there is an Enhanced Risk for severe
weather which will likely necessitate a number of Special Marine
Warnings. For those with outdoor plans on Independence Day, make
sure you have multiple ways to receive hazardous weather alerts.
A brunt of the activity is expected in the late afternoon to
evening hours, but this could fester into the overnight hours as
well. Additional storms are possible on Sunday into Monday which
will make for hazardous conditions at times over the waters.

&&

.CLIMATE...
There is a Significant Heat Risk today (Independence Day). The
numbers below aren`t a forecast, but rather a reference for
historical context for comparison. Latest forecast:
weather.gov/lwx. A number of daily records have been broken at
the local airports the past couple of days (July 1-3).

==================================================================
                    *** ALL-TIME RECORD HIGHS ***
==================================================================
Baltimore                 107 (set on Jul 10, 1936)
Washington                106 (set on Jul 20, 1930 + Aug 06, 1918)
Sterling-Dulles Airport   105 (set on Jul 22, 2011)
Baltimore Downtown        108 (set on Jul 07, 2012 + Jul 22, 2011)
Annapolis                 106 (set on Aug 06, 1918)
Hagerstown                105 (set on Jul 14, 1954)
Martinsburg               112 (set on Jul 11, 1936)
Charlottesville           107 (set on Sep 07, 1954 + 3 other times)

==================================================================
                  *** ALL-TIME RECORD WARM LOWS ***
==================================================================
Baltimore                  83 (set on Aug 05, 1930 + 2 other times)
Washington                 84 (set on Jul 24, 2011 + 2 other times)
Sterling-Dulles Airport    79 (set on Aug 08, 2007)
Baltimore Downtown         88 (set on Jul 22, 2011 and Jul 10, 1993)
Annapolis                  92 (set on Jul 07, 1994)
Hagerstown                 86 (set on Jun 15, 1899)
Martinsburg                86 (set on Jul 21, 1930)
Charlottesville            85 (set on Aug 07, 1918)

==================================================================
                  *** JULY MONTHLY RECORD HIGHS ***
==================================================================
Baltimore                 107 (set on Jul 10, 1936)
Washington                106 (set on Jul 20, 1930)
Sterling-Dulles Airport   105 (set on Jul 22, 2011)
Baltimore Downtown        108 (set on Jul 07, 2012 + Jul 22, 2011)
Annapolis                 105 (set on Jul 21, 1930 + Jul 02, 1901)
Hagerstown                105 (set on Jul 14, 1954)
Martinsburg               112 (set on Jul 11, 1936)
Charlottesville           107 (set on Jul 10, 1936 + Jul 20, 1930)

==================================================================
                 *** JULY MONTHLY RECORD WARM LOWS ***
==================================================================
Baltimore                  83 (set on Jul 21, 1930)
Washington                 84 (set on Jul 24, 2011 + 2 other times)
Sterling-Dulles Airport    78 (set on Jul 24, 2010 + Jul 08, 2010)
Baltimore Downtown         88 (set on Jul 22, 2011 + Jul 10, 1993)
Annapolis                  92 (set on Jul 07, 1994)
Hagerstown                 83 (set on Jul 24, 2010)
Martinsburg                86 (set on Jul 21, 1930)
Charlottesville            84 (set on Jul 22, 1930)

==================================================================
               *** DAILY RECORD HIGHS | WARM LOWS ***
                          VALID: Jul 04
==================================================================
Baltimore                100 (2002 + 2)    |   78 (1911)
Washington               100 (1919)        |   80 (2018 + 2002)
Sterling-Dulles Airport   97 (2002 + 1999) |   75 (2018)
Baltimore Downtown       101 (2002 + 1990) |   83 (2002)
Annapolis                 98 (1999)        |   81 (2018)
Hagerstown               100 (1966 + 1919) |   76 (2018)
Martinsburg              103 (1898)        |   76 (1999)
Charlottesville          100 (2012)        |   78 (1919)

-----------------------------------------------------------------

             Number of Consecutive Days Max Temp >=100
Area (obs site)              Records since

------------------------------------------------------------------
Baltimore (BWI)          4 days  July 14-17,2024 & July 19-22,1930
Washington (DCA)         4 days  July 14-17, 2024 & July 5-8, 2012
Sterling-Dulles (IAD)    2 days  July 7-8, 2012, July 21-22, 2011
                                 July 6-7, 2010, July 16-17, 1997

Baltimore Downtown (DMH) 5 days July 3-7, 2010 & July 7-11, 1993
Annapolis (NAK)          1 day  July 21, 2019, July 7, 2012,
                                July 22, 2011, June 29, 1959

Hagerstown (HGR)         3 days July 5-7, 2010
Martinsburg (MRB)        6 days June 1-6, 1925
Charlottesville (CHO)    5 days July 4-8, 2012



     Period of Record (POR) context...
Area (obs site)              Records since
------------------------------------------------------------------
Baltimore (BWI)                     Jan 1872
Washington (DCA)                    Jul 1872
Sterling-Dulles Airport (IAD)       Jan 1960
Baltimore Downtown (DMH)            Jul 1950
Annapolis (NAK)                     Jan 1894
Hagerstown (HGR)                    Jan 1899
Martinsburg (MRB)                   Jan 1891
Charlottesville (CHO)               Jan 1893

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Extreme Heat Warning from 10 AM this morning to 9 PM EDT this
     evening for DCZ001.
MD...Extreme Heat Warning from 10 AM this morning to 9 PM EDT this
     evening for MDZ004>006-008-011-013-014-016>018-503>508.
     Extreme Heat Warning from 10 AM this morning to 8 PM EDT this
     evening for MDZ003.
     Heat Advisory from 10 AM this morning to 8 PM EDT this evening
     for MDZ502.
VA...Extreme Heat Warning from 10 AM this morning to 9 PM EDT this
     evening for VAZ036>040-050-051-053>057-501-502-505-506-
     526-527.
     Extreme Heat Warning from 10 AM this morning to 8 PM EDT this
     evening for VAZ027>031.
     Heat Advisory from 10 AM this morning to 8 PM EDT this evening
     for VAZ025-026-504.
WV...Extreme Heat Warning from 10 AM this morning to 8 PM EDT this
     evening for WVZ050>053-055.
     Heat Advisory from 10 AM this morning to 8 PM EDT this evening
     for WVZ502-504-506.
MARINE...Extreme Heat Warning from 10 AM this morning to 9 PM EDT this
     evening for ANZ530.

&&

$$

DISCUSSION...BRO
AVIATION...BRO
MARINE...BRO
CLIMATE...LWX