Arlington, Virginia 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

499
FXUS61 KLWX 301301
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
901 AM EDT Tue Jun 30 2026

.WHAT HAS CHANGED...
No changes were made to the forecast this morning other than the
mention of a brief light shower near Allegany County MD.

&&

.KEY MESSAGES...
- (1) Significant heat wave builds through the week.

- (2) An increased risk for severe thunderstorms Friday into
  the Independence Day weekend.

&&

.DISCUSSION...
KEY MESSAGE 1...Significant heat wave builds through the week.

Skies remain mostly clear early this morning, with patchy fog
mainly to the west of the Blue Ridge. Any patchy fog should
quickly burn off after sunrise, giving way to mostly sunny skies
today. Heat and humidity will continue to slowly build in from
the west, with temperatures climbing into the upper 80s and
lower 90s this afternoon. Dewpoints will climb into the upper
60s and lower 70s to the west of the Blue Ridge, while locations
further east will mix down into the upper 50s and lower 60s.
This will actually make it feel warmer and more humid to the
west of the Blue Ridge today. Heat Advisories are in effect for
locations just in the lee of the Alleghenies where heat indices
are forecast to reach 100 degrees today. As the higher dewpoint
air builds in from the west, locations to the west of the Blue
Ridge will also start to destabilize this afternoon. Model
soundings show signs of capping this afternoon, but a stray
shower or storm can`t be ruled out over the Alleghenies or
Potomac Highlands. If a stronger storm were to get going, it
could potentially produce gusty winds, given MLCAPE values
increasing to around 2000 J/kg and DCAPE increasing to around
1000 J/kg.

Heat and humidity will continue to build tomorrow as upper level
ridging slowly moves eastward. Most locations will see high
temperatures in the upper 90s to around 100. When combined with
dewpoints in the lower to middle 70s, this will push heat
indices over 100 degrees to the west of the Blue Ridge, and over
105 further east. The exception will be across Southern
Maryland, where the higher dewpoint air will move in last
(leading to heat indices between 100 and 104). Heat Advisories
have been issued on Wednesday for all of the forecast area, with
the exception of the Alleghenies, Blue Ridge, and Southern
Maryland.

We`ll also need to keep an eye on the potential for showers and
thunderstorms tomorrow afternoon and evening. The synoptic
environment isn`t the most favorable for storms, with upper
level ridging moving in. Model soundings also show some subtle
capping. However, most guidance does have a lee trough setting
up to the east of the Blue Ridge, and several models do show a
few showers or storms forming within that surface trough. While
coverage of showers and storms will likely remain low (if they
occur at all) the thermodynamic environment looks very
volatile, with MLCAPE values increasing to near 3000 J/kg, DCAPE
values around 1400-1600 J/kg, very steep low-level lapse rates,
and an elevated mixed layer present aloft. Shear is largely
lacking, but if any more robust storms were to develop, they
could be capable of producing very strong downbursts. We`ll
continue to keep an eye on this conditional threat over the next
day.

The peak of the heat and humidity will build in for Thursday and
Friday, with air temperatures likely rising to between 100 and
105 degrees at lower elevations. When combined with dewpoints in
the upper 60s to around 70, heat indices could potentially reach
around 110 to the east of the Blue Ridge, and around 105 west of
the Blue Ridge. As a result, Extreme Heat Watches have been
issued for the majority of the forecast area for Thursday and
Friday.

The heat and humidity will likely linger into the upcoming
weekend, but forecast confidence regarding exact temperatures
starts to decrease a bit. So for now the Extreme Heat Watch
doesn`t extend into this weekend. However, it could potentially
get extended at a later time. As of now, temperatures are
forecast to reach into the upper 90s to low 100s on
Saturday/Independence Day, and low to mid 90s on Sunday.


KEY MESSAGE 2...An increased risk for severe thunderstorms Friday
into the Independence Day weekend.

With excessive heat and humidity comes the potential for severe
weather as abundant instability and moisture pool over the region.
Upper level ridging will gradually buckle Friday before flattening
over the weekend into early next week as the broad subtropical high
pressure shifts further offshore and a series of shortwave
disturbances pivot through. Timing and coverage of storms have yet
to be determined given the placement of synoptic/mesoscale features.
With that said, looking at scattered strong to severe thunderstorms
mainly during the afternoon and evening period with damaging wind
gusts, large hail, heavy rainfall, and frequent lightning as the
main threats. Storms may be of the pulse variety likely forming
along the lee side trough east of the Alleghenies or residual
outflows (i.e the bay/river breeze) due to the lack shear aloft. Of
course this is subject to change based upon any ripples of energy
that move between over top the ridge shunted to the south and jet
stream to the north (Great Lakes/Ohio River Valley). If this were to
occur we could be looking at more organized and widespread storm
clusters, but confidence in this is low at this time. Multiple
instances of deterministic/ensemble guidance illustrate this on both
Saturday and Sunday as the ridge flattens. Google AI WxNet along
with CIPS/CSU AI probs illustrate this similar notion with how their
outlooks/probabilities are drawn given the flattening ridge.

As we approach the Independence Day weekend, have a weather
preparedness plan ready to go, especially if you are outdoors (i.e
at a picnic with family or a fireworks show). Plan ahead for any
outdoor activities this weekend, as they are likely to be
interrupted by storms at some point. Have a way to get trusted
warnings, download a radar/lightning app to keep aware of changing
weather conditions, and know when to act when thunder roars to go
indoors. Given the heat in place, some storms could be quite intense
(if they form). From a historical perspective, prolonged near record
heat in summer often ends in a period of strong storms.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
Prevailing VFR conditions are expected through Thursday. Winds
are expected to remain out of the south today, before becoming
southwesterly on Wednesday. Afternoon bay breezes may cause more
E/SE flow at MTN and possibly BWI. Dry weather is expected
through mid week, though a pop up t-storm can`t be ruled out
near any bay breezes (especially Wednesday).

VFR conditions are expected Thursday through Friday morning.
Intermittent sub-VFR conditions return Friday afternoon and evening
and again during the diurnal periods this weekend as thunderstorm
chances increase. Should thunderstorms materialize, some could
become severe resulting in chaotic wind speeds and directions.

&&

.MARINE...
Southerly winds are forecast over the waters for today through
Thursday, with SCAs in effect this afternoon into tonight.
Additional SCAs may be needed Wednesday afternoon and evening.

Sub-SCA level winds are expected Friday through the
Independence Day weekend. Thunderstorm chances increase over the
waters Friday afternoon into the weekend. Should these
conditions materialize, Special Marine Warnings could become
necessary. Winds generally flow south to southwesterly.

&&

.TIDES/COASTAL FLOODING...
Increasing southerly flow could cause near minor flooding
particularly at Annapolis and possibly Havre de Grace, Bowley`s
Quarters and Alexandria early Wednesday morning.

&&

.CLIMATE...
There is a significant heat risk this week. The numbers below
aren`t a forecast, but rather a reference for historical context
for comparison. Latest forecast: weather.gov/lwx.

==================================================================
                    *** 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 01
==================================================================
Baltimore                103 (1901)        |   80 (1933 + 1901)
Washington               102 (1901)        |   79 (1977)
Sterling-Dulles Airport   96 (2012)        |   72 (2017 + 3)
Baltimore Downtown       101 (2012)        |   82 (2012)
Annapolis                103 (1901)        |   79 (1945 + 1901)
Hagerstown               100 (1901)        |   74 (2017 + 1977)
Martinsburg              102 (1933)        |   74 (1933)
Charlottesville          101 (2012 + 1945) |   78 (1901)

==================================================================
               *** DAILY RECORD HIGHS | WARM LOWS ***
                          VALID: Jul 02
==================================================================
Baltimore                103 (1901)        |   80 (1901)
Washington               101 (1898)        |   79 (2012 + 1872)
Sterling-Dulles Airport   98 (1966)        |   75 (2022)
Baltimore Downtown       102 (1966)        |   84 (2002)
Annapolis                105 (1901)        |   80 (1901)
Hagerstown               100 (1966)        |   74 (2018 + 1901)
Martinsburg              102 (1933 + 1931) |   75 (1933 + 1901)
Charlottesville          100 (1954)        |   76 (1910)

==================================================================
               *** DAILY RECORD HIGHS | WARM LOWS ***
                          VALID: Jul 04
==================================================================
Baltimore                104 (1898)        |   80 (1898)
Washington               101 (1966 + 2)    |   80 (2018)
Sterling-Dulles Airport  103 (1966)        |   73 (2018 + 2)
Baltimore Downtown       102 (1997)        |   82 (2018 + 1983)
Annapolis                100 (1901)        |   84 (1896)
Hagerstown               102 (1966)        |   76 (2002)
Martinsburg              102 (1941 + 1911) |   74 (1980)
Charlottesville          100 (1966 + 1954) |   79 (1911)

==================================================================
               *** 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)


     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...Heat Advisory from 11 AM to 8 PM EDT Wednesday for DCZ001.
     Extreme Heat Watch from Thursday morning through Friday
     evening for DCZ001.
MD...Heat Advisory from 11 AM to 8 PM EDT Wednesday for MDZ003>006-
     008-011-013-014-016-503>508.
     Extreme Heat Watch from Thursday morning through Friday
     evening for MDZ003>006-008-011-013-014-016>018-502>508.
     Heat Advisory until 8 PM EDT Wednesday for MDZ502.
VA...Heat Advisory from 11 AM to 8 PM EDT Wednesday for VAZ025>031-
     036>040-050-051-053>057-501-502-504>506-526-527.
     Extreme Heat Watch from Thursday morning through Friday
     evening for VAZ027>031-039-040-050-051-053>057-501-502-
     505-506-526-527.
WV...Heat Advisory from 11 AM to 8 PM EDT Wednesday for WVZ051>053.
     Extreme Heat Watch from Thursday morning through Friday
     evening for WVZ050>053-055-502-504.
     Heat Advisory until 8 PM EDT Wednesday for WVZ050-055-502-504-
     506.
MARINE...Small Craft Advisory from 5 PM this afternoon to 6 AM EDT
     Wednesday for ANZ530-534-539>541-543.
     Heat Advisory from 11 AM to 8 PM EDT Wednesday for ANZ530.
     Extreme Heat Watch from Thursday morning through Friday
     evening for ANZ530.
     Small Craft Advisory from 2 PM this afternoon to 6 AM EDT
     Wednesday for ANZ531>533.
     Small Craft Advisory from 5 PM this afternoon to 1 AM EDT
     Wednesday for ANZ535-538.
     Small Craft Advisory from 2 PM this afternoon to 1 AM EDT
     Wednesday for ANZ536-537-542.

&&

$$

DISCUSSION...BRO/DHOF/KJP/EST
AVIATION...DHOF/KJP/EST
MARINE...DHOF/KJP/EST
TIDES/COASTAL FLOODING...DHOF/BRO/KJP
CLIMATE...DHOF