Area Forecast Discussion
Issued by NWS Sterling, VA
Issued by NWS Sterling, VA
470
FXUS61 KLWX 240800
AFDLWX
Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Tue Jun 24 2025
.SYNOPSIS...
A prolonged period of very hot weather is expected through the
middle of the week as a large ridge of high pressure builds
over the eastern United States. A risk of showers and
thunderstorms returns during the middle to latter portions of
the week as a frontal system stalls nearby. This system
eventually lifts northward into New England over the weekend.
&&
.NEAR TERM /THROUGH TONIGHT/...
As has been advertised in recent days, overnight conditions
would be very warm and humid. The current 07Z/3 AM temperatures
and dew points across the region certainly represent this
summertime script quite well. More specifically, a majority of
the area is well into the 70s with a number of low 80s across
D.C. and Baltimore, as well as near any river/bay influences.
Given dew points holding steady in the low/mid 70s, current heat
indices are running well into the 80s to near 90 degrees. This
will continue to make it important to find ways to stay cool
during the overnight hours. All of this heat will again lend
itself to another toasty day across the Mid-Atlantic region.
On the synoptic-scale, the culprit for such hot temperatures is
an anomalously strong upper ridge parked over the eastern U.S.
With 500-mb heights generally around 597-598 dm, this is easily
around 2 standard deviations above late June climatology.
Expected 850-mb temperatures will run between 22-24C which dry
adiabatically mixed down to the ground favors triple digit
temperatures. A large portion of the region will see high
temperatures ranging between 98 and 101 degrees. Even the usual
cooler spots in the mountains can expect widespread 80s to low
90s. Based on the current daily records, a number of temperature
records may be tied or broken (highs and warm overnight lows).
For more information, scroll down to the Climate section for
additional details. Remember, with heat indices rising into the
100 to 110 degree range today, a mixture of Extreme Heat
Warnings and Heat Advisories are in place from 11 AM to 9 PM.
Overall storm chances appear limited given the degree of
subsidence underneath the strong anticyclone aloft.
Additionally, a number of solutions keep the 700-300 mb layer
rather dry which would limit any vertical cloud development.
While subsidence could easily win out today, there are a few
high-resolution models that fire off convection over the central
Virginia Blue Ridge. If such thunderstorms developed, inverted-V
signatures within the surface to 850-mb layer would be conducive
to fairly strong downbursts (DCAPE values of 1,000 to 1,300
J/kg). Such storms would quickly propagate toward the southeast
into central Virginia. However, given the mentioned limitations
under the ridge, it remains to be seen if any such storm would
form. Otherwise, hot and humid conditions will largely rule the
day with some flat fair weather cumulus percolating up during
diurnal heating.
Do not expect much change in the pattern into tonight with
continued dangerous heat and humidity. Perhaps a degree or two
is shaved off overnight lows relative to what is occurring right
now. However, these readings are still above average and coupled
with dew points staying in the low/mid 70s. Depending on if
storms develop, some cirrus debris could linger overhead across
the more southern areas.
&&
.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
While the mid/upper ridge remains in charge into the middle of
the week, heights actually do lower by around 3 to 5 dm.
Although this may seem subtle, it should lead to some shifts in
the overall pattern which includes increasing convective
chances. As this erosion of the northern flank of the ridge
occurs, a slow moving frontal zone approaches the Mason-Dixon
Line from the north on Wednesday. Not only will forcing improve
as mesoscale shortwaves traverse the region, there should be an
added focus from the boundary sagging southward in time. Given
the degree of cloud cover and possible convective contamination,
high temperatures are somewhat in the air on Wednesday.
Extreme Heat Watches remain in effect from 11 AM until 9 PM
across the northern Shenandoah Valley, portions of the eastern
West Virginia panhandle, and all areas east of the Blue Ridge
Mountains. Generally speaking, heat indices could rise to around
105 degrees over the Shenandoah Valley. Meanwhile, heat indices
could approach 110 degrees for locations off to the east. As
mentioned earlier, it is uncertain if this is achieved as
clouds and showers would mitigate a shot at upper 90s high
temperatures. In this forecast package, erred on the side of
caution by going with mainly mid/upper 90s in the hottest spots,
with heat indices about 10 degrees above this. Any decisions on
upgrading this watch should occur later today.
As mentioned, thunderstorms are more likely to play a role in
Wednesday`s weather. The Storm Prediction Center has placed the
entire region in a Marginal risk for severe weather. Locally
stronger downbursts may pose a threat for damaging wind gusts.
Given the degree of heat and humidity in the atmosphere, some
storms linger into the first half of the night. Low temperatures
remain fairly close to preceding nights.
Thursday marks the first real drop in temperatures with a
forecast of upper 80s to mid 90s. Given elevated humidity
levels, heat indices do still push into the 100 to 105 degree
range. Shower and thunderstorms chances further increase as the
boundary meanders about the area, some of which may be severe in
nature. With anomalous moisture in place, a non-zero threat for
flash flooding also exists, particularly for training elements
along this front. Conditions remain unsettled into subsequent
days.
&&
.LONG TERM /FRIDAY THROUGH MONDAY/...
Mid-level ridging finally begins to break down this weekend, as flow
aloft becomes zonal through the start of next week. Hot and humid
conditions are expected to persist, though closer to seasonal values
with highs in the upper 80s to low 90s and heat indices between 95-
105. Daily showers and thunderstorms are in the forecast from the
end of this week through the start of next week. Ample instability
and deep moisture will be present to fuel scattered to numerous
storms each day. Light steering flow could produce a threat for
localized flooding some days.
&&
.AVIATION /07Z TUESDAY THROUGH SATURDAY/...
Conditions should remain VFR today underneath the strong upper
ridge. Although the area is expected to stay dry, an isolated
thunderstorm may fire off over the central Virginia Blue Ridge.
This could near the KCHO terminal area during the 21-00Z
timeframe (PROB30 accounts for this). Otherwise, gradients
remain weak with northwesterly winds under 10 knots.
A slow moving frontal zone approaches the Mason-Dixon Line from
the north on Wednesday. This will increase opportunities for
showers and thunderstorms on both Wednesday and Thursday. Some
restrictions are possible as the pattern shifts toward more
active weather. Weak pressure gradients will keep winds
generally under 10 knots outside of any convection.
VFR conditions prevail this weekend into Monday. Daily afternoon to
evening showers and thunderstorms are likely, and any of these could
produce brief periods of sub-VFR conditions.
&&
.MARINE...
Weak summertime gradients will maintain sub-advisory level winds
over the waters through Thursday. Conditions will be dry today,
but with hot and humid weather expected. As a slow moving
frontal zone nears southern Pennsylvania from the north, shower
and thunderstorm chances will increase during subsequent days.
Hazardous marine conditions are possible on Wednesday and
Thursday, particularly during the afternoon/evening hours. A few
Special Marine Warnings are possible for the stronger storms.
Winds remain light this weekend through the start of next week.
Daily showers and thunderstorms return to the forecast, so any
isolated strong storm could bring a threat of gusty winds and
lightning.
&&
.TIDES/COASTAL FLOODING...
Tidal anomalies will remain slightly elevated through the next
several high tide cycles. This will keep water levels slightly
elevated for the more sensitive tidal sites. At this point, only
Fort McHenry and Annapolis are slated to reach Action stage
during the next couple of astronomical high tides. Expect the
shift to northwesterly winds to lower anomalies over the next
day or two.
&&
.CLIMATE...
Here are some daily high temperature records during the June
24-27, 2025 timeframe:
A `+` sign indicates multiple years currently hold that record.
***TUESDAY, JUNE 24TH, 2025***
LOCATION RECORD HIGH (YEAR) RECORD WARM LOW (YEAR)
Washington-National (DCA) 100F (2010) 78F (2010)
Washington-Dulles (IAD) 97F (2010) 73F (2010)
Baltimore (BWI) 100F (2010) 76F (2010)+
Baltimore Inner Harbor (DMH) 101F (2010)+ 82F (2010)
Martinsburg (MRB) 97F (1943) 70F (2024)+
Charlottesville (CHO) 101F (1930) 74F (1914)
Annapolis (NAK) 97F (2000)+ 81F (1896)
Hagerstown (HGR) 96F (2010)+ 75F (2010)
***WEDNESDAY, JUNE 25TH, 2025***
LOCATION RECORD HIGH (YEAR) RECORD WARM LOW (YEAR)
Washington-National (DCA) 100F (1977) 76F (2010)+
Washington-Dulles (IAD) 97F (1966) 71F (1981)
Baltimore (BWI) 99F (1997) 77F (1949)+
Baltimore Inner Harbor (DMH) 104F (1997) 79F (1998)+
Martinsburg (MRB) 99F (1997) 72F (1949)
Charlottesville (CHO) 99F (1997) 77F (1951)
Annapolis (NAK) 98F (2000)+ 78F (1997)+
Hagerstown (HGR) 98F (1952) 75F (1949)
***THURSDAY, JUNE 26TH, 2025***
LOCATION RECORD HIGH (YEAR) RECORD WARM LOW (YEAR)
Washington-National (DCA) 101F (1952) 77F (1952)+
Washington-Dulles (IAD) 99F (2024) 72F (2023)+
Baltimore (BWI) 99F (2024)+ 80F (1952)
Baltimore Inner Harbor (DMH) 104F (1998) 83F (1952)
Martinsburg (MRB) 102F (1943) 75F (1949)
Charlottesville (CHO) 99F (1998) 78F (1952)
Annapolis (NAK) 98F (1998)+ 81F (1952)
Hagerstown (HGR) 98F (1954)+ 75F (1952)
***FRIDAY, JUNE 27TH, 2025***
LOCATION RECORD HIGH (YEAR) RECORD WARM LOW (YEAR)
Washington-National (DCA) 99F (2010) 80F (1952)
Washington-Dulles (IAD) 100F (1964) 72F (2021)+
Baltimore (BWI) 100F (2010) 78F (1949)+
Baltimore Inner Harbor (DMH) 101F (2010) 83F (1998)
Martinsburg (MRB) 101F (1943) 75F (1952)
Charlottesville (CHO) 100F (1952) 79F (1952)
Annapolis (NAK) 98F (1911) 79F (1943)
Hagerstown (HGR) 99F (2010) 77F (1952)
&&
.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Extreme Heat Warning from 11 AM this morning to 9 PM EDT this
evening for DCZ001.
Extreme Heat Watch from Wednesday morning through Wednesday
evening for DCZ001.
MD...Air Quality Alert until midnight EDT tonight for MDZ008-508.
Extreme Heat Warning from 11 AM this morning to 9 PM EDT this
evening for MDZ003>006-008-011-013-014-016>018-503>508.
Extreme Heat Watch from Wednesday morning through Wednesday
evening for MDZ003>006-008-011-013-014-016>018-503>508.
Heat Advisory from 11 AM this morning to 9 PM EDT this evening
for MDZ502.
VA...Extreme Heat Warning from 11 AM this morning to 9 PM EDT this
evening for VAZ027>031-036>040-050-051-053>057-501-502-
505-506-526-527.
Extreme Heat Watch from Wednesday morning through Wednesday
evening for VAZ027>031-036>040-050-051-053>057-501-502-
505-506-526-527.
Heat Advisory from 11 AM this morning to 9 PM EDT this evening
for VAZ025-026.
WV...Extreme Heat Warning from 11 AM this morning to 9 PM EDT this
evening for WVZ052-053.
Extreme Heat Watch from Wednesday morning through Wednesday
evening for WVZ052-053.
Heat Advisory from 11 AM this morning to 9 PM EDT this evening
for WVZ050-051-055-502-504-506.
MARINE...Air Quality Alert until midnight EDT tonight for ANZ530.
Extreme Heat Warning from 11 AM this morning to 9 PM EDT this
evening for ANZ530.
Extreme Heat Watch from Wednesday morning through Wednesday
evening for ANZ530.
&&
$$
SYNOPSIS...BRO
NEAR TERM...BRO
SHORT TERM...BRO
LONG TERM...KRR
AVIATION...BRO/KRR
MARINE...BRO/KRR
TIDES/COASTAL FLOODING...LWX
CLIMATE...LWX