263
FXUS61 KLWX 260800
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Thu Jun 26 2025

.SYNOPSIS...
A ridge of high pressure overhead will maintain hot conditions
through this evening. Daily chances for showers and
thunderstorms will increase through the end of the week. A weak
frontal boundary will slowly drift southward in time before
stalling nearby through Friday. This system gradually lifts
northward away from the area this weekend. A stronger cold
front may cross the region by early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
While conditions are seasonably warm and humid across the area,
24-hour temperature/dew point departures have suggested a subtle
cooling/drying trend. Current readings are mainly in the upper
60s to mid 70s, with spotty upper 70s within D.C. and Baltimore,
as well as near the tidal Potomac and Chesapeake Bay. With dew
points holding steady in the upper 60s to low 70s, elevated heat
indices are not currently an issue.

Aside from a few pop-up showers off to the south near Richmond,
Virginia, the area has remained dry over the past several hours.
Have opted to remove the threat of any such showers through
mid-morning. Otherwise, a few high clouds continue to pass
overhead with areas of patchy fog. Such instances of fog are
focusing over the typical favored locations from Stafford County
westward across the Shenandoah Valley into the Potomac
Highlands (this excludes the Blue Ridge Mountains). Expect this
to quickly burn off an hour or so after sunrise.

With the longstanding upper ridge continuing to flatten out, a
stalled surface boundary across northern Pennsylvania/Ohio is
expected to sag southward in time. As this occurs, enhanced
frontal lift coupled with perturbations in the mid/upper
atmosphere will favor an increasing risk of showers and
thunderstorms. With afternoon high temperatures rising into the
low/mid 90s and continued humid conditions, instability profiles
remain quite robust. Forecast surface-based CAPE values rise
into the 2,500 to 3,500 J/kg range, but with rather weak deep-
layer shear (averaging around 10 knots). This lack of vertical
shear suggests disorganized convection while focusing more
intently on mesoscale boundaries (i.e., river and bay breezes,
as well as old convective outflows/cold pools). Given a lack of
inhibition, updraft development should commence by the early
afternoon and continue through the core heating hours of the
day.

As mentioned above, thunderstorm development should be rather
widespread. Despite the lack of shear, steepening low-level
lapse rates will contribute to DCAPE (downdraft CAPE) values to
around 1,000 J/kg. This layer should accelerate water-loaded
downdrafts to the surface with a damaging wind signature likely
in taller/stronger cells. A Marginal risk for severe
thunderstorms continues to be advertised by the Storm Prediction
Center. Additionally, with precipitable water values around 2
inches, slow cell motions, and the potential of repeat
convection, flash flooding is possible this afternoon/evening.
The Weather Prediction Center has painted a Slight risk for
flash flooding across areas east of the Catoctins and Blue
Ridge. Most high-resolution models depict activity waning after
midnight so any severe/flood threat should wane at that point.

Besides the convective threats, continued above average
temperatures and high humidity levels will carry heat indices
into the 102 to 107 degree range. Furthermore, Heat Advisories
extend over a bulk of the area outside the mountains from 11 AM
until 7 PM this evening. Continue to find ways to stay cool in
the heat by taking plenty of breaks from the outdoors, staying
hydrated, and wearing light clothing. Heading into the overnight
hours, the influence of rain-cooled air should help carry lows
into the upper 60s to low 70s (low/mid 60s in the mountains).

&&

.SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/...
While the placement of the frontal zone is uncertain and likely
re-positioned by convective-scale processes, this system should
be in the vicinity of the Mid-Atlantic region on Friday. Not
only will this carry an additional risk for showers and
thunderstorms, but also comes with a challenging temperature
forecast. For those in the cool sector to the north, highs in
the mid/upper 70s are likely. Off to the south, the warm/moist
sector will support temperatures well into the 80s to near 90
degrees. The current forecast calls for this separation of air
masses to be between I-70 and I-66.

There should be a particular focus for convection in the
vicinity of this frontal zone where lift will be augmented.
Along and south of this front will yield a severe weather
component to the storms where instability is maximimzed.
Additionally, well above average columnal moisture profiles
favor further instances of flooding potential. It is difficult
to say where this will occur, but the usual focuses would be in
the urban corridors and regions hit by previous days of heavy
rainfall. Depending on how quickly instability is exhausted,
some of the convection could fester into the overnight hours on
Friday.

With mid/upper height changes being somewhat neutral, it
remains to be seen how much northward progress this boundary
makes on Saturday. This system could easily linger right near
the Mason-Dixon Line which would maintain a more unsettled
pattern during the first half of the weekend. The expectation is
for this boundary to drift northward in time on Saturday which
will help usher highs back into the upper 80s to low 90s.
Further, convection would be driven more heavily by instability
versus along any particular frontal boundaries. But as
mentioned, there is plenty of uncertainty in how this all plays
out. Will see Saturday night`s lows be a tad milder than
previous nights with readings in the upper 60s to mid 70s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The Summertime convection threat continues each day Sunday
through Tuesday, mainly in the afternoon and evening hours when
it is the warmest. High temperatures will reach the lower to
middle 90s each afternoon. A strong upper trough and associated
surface cold front is expected to cross the area on Tuesday.
This could lead to an active afternoon and evening with multiple
rounds of convection and/or severe thunderstorms. High pressure
builds in the wake by the middle of next week which favors a
return to drier weather.


&&

.AVIATION /07Z THURSDAY THROUGH MONDAY/...
With convection in the forecast through the remainder of the
work week and into the first half of the weekend, periods of
restrictions are looking likely at times. Otherwise, VFR
conditions should be commonplace outside of these convective
episodes. For this afternoon/evening, remain confident enough in
thunderstorm development to have a 3 to 4 hour period of TSRA
restrictions roughly between 20-00Z. As some of this may linger
after dark, have maintained the PROB30 groups into subsequent
hours as inherited by previous shifts.

As a frontal zone drifts southward across the area, winds turn
more easterly in nature on Friday. Eventually this boundary does
return northward as a warm front which would bring a return to
south-southwesterlies at some point on Saturday. And as
mentioned, restrictions are possible given a decent chance for
thunderstorms each afternoon/evening.

VFR conditions at all terminals Sunday through Monday night. At
times of convection, we could see brief MVFR visibility and/or
ceilings. Winds will be light and variable, except higher gusts
in strong thunderstorms.

&&

.MARINE...
While gradients remain weak enough to keep the waterways free of
Small Craft Advisories, the threat of convection will make for
hazardous boating conditions at times through at least Saturday.
It is difficult to say which day will be the most active in
terms of thunderstorm development, but the degree of continued
heat and humidity should maintain a daily 30-60 percent chance
of storms each afternoon/evening. As usual, frequent lightning
is possible in any such storm, with the stronger cells likely
requiring Special Marine Warnings.

No marine hazards Sunday through Monday night. If thunderstorms
move out over the waters, then Special Marine Warnings may be
warranted. Winds light and variable through the period, except
higher gusts in strong thunderstorms.


&&

.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
Annapolis is slated to reach Action stage during the next
couple of astronomical high tides.

&&

.CLIMATE...
Here are some daily high temperature records on June 26, 2025:

A `+` sign indicates multiple years currently hold that record.

                 ***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)

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Heat Advisory from 11 AM this morning to 7 PM EDT this evening
     for DCZ001.
MD...Heat Advisory from 11 AM this morning to 7 PM EDT this evening
     for MDZ003>006-008-011-013-014-016>018-502>508.
VA...Heat Advisory from 11 AM this morning to 7 PM EDT this evening
     for VAZ026>031-036>040-050-051-053>057-501-502-505-506-
     526-527.
WV...Heat Advisory from 11 AM this morning to 7 PM EDT this evening
     for WVZ050>053-055-502-504.
MARINE...Heat Advisory from 11 AM this morning to 7 PM EDT this evening
     for ANZ530.

&&

$$

SYNOPSIS...BRO
NEAR TERM...BRO
SHORT TERM...BRO
LONG TERM...BRO/KLW
AVIATION...BRO/KLW
MARINE...BRO/KLW
TIDES/COASTAL FLOODING...LWX
CLIMATE...LWX