424
FXUS61 KLWX 250800
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Wed Jun 25 2025

.SYNOPSIS...
A ridge of high pressure overhead will bring continued hot
conditions over the next couple of days. As the upper-level
ridge slowly weakens in the coming days, 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 on Thursday into Friday. This system
lifts northward into New England this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
With a wavy frontal zone arcing across southern portions of the
Great Lakes into the Cornbelt states, the local area is fully
entrenched within the warm/moist sector. This is evident in the
07Z/3 AM temperatures and dew points across the Mid-Atlantic
states. Current readings are well into the 70s with spotty low
80s scattered about the area. This is coupled with light winds
and dew points in the low/mid 70s which yields overnight heat
indices well into the 80s to near 90 degrees. As such, the
threat for heat illnesses will remain, particularly for those
without access to cooling systems.

Although very isolated showers have popped up over the last few
hours, these have generally been short lived and transient in
nature. Thus, expect a mainly dry forecast heading into the day.
Like preceding days, it will be another hot one across the area.
However, the longstanding 597-dm mid-level ridge centered over
the eastern U.S. will have weakened a bit during the past 12 to
24 hours. While still quite hot this afternoon, triple digit
temperatures are less likely with mainly mid/upper 90s scattered
about the region. With humidity levels remaining high,
resultant heat indices should largely range between 100 to 108
degrees. Consequently, Heat Advisories span all locations
outside of the Allegheny Front and Blue Ridge Mountains from 11
AM until 9 PM. Continue to find ways to stay cool and hydrated,
while taking many breaks if outside for longer periods of time.

Unlike previous days, thunderstorm chances will increase today
given the reduction in the strength of this mid/upper ridge. The
gradual lowering of heights coupled with a slew of embedded
shortwaves tracking across the area should help ignite isolated
to scattered showers and thunderstorms. Given much of this will
be instability driven (continued extensive heat and humidity),
these should be diurnally focused storms for the afternoon to
evening hours. Some of the stronger updrafts will have the
potential of producing damaging wind gusts. Forecast soundings
over the area show an inverted-V looking profile which are more
conducive to downbursts given evaporative cooling effects below
the cloud base. Expected DCAPE (downdraft CAPE) values push to
near 1,000 J/kg which is plenty sufficient for damaging wind
gusts. The Storm Prediction Center has maintained a broad
Marginal risk for severe storms for today.

Most high-resolution models show activity waning into the
overnight hours given the loss of diabatic heating. In the wake
of these storms, expect another warm and humid night ahead with
temperatures a smidge lower than current conditions. Forecast
low temperatures will be in the 70s with mid/upper 60s across
mountain locales.

&&

.SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/...
The mentioned west-east oriented frontal zone across southern
sections of the Great Lakes is expected to sag southward in
time. By Thursday, the forecast frontal analysis places this
boundary just north of the Mason-Dixon Line. Consequently, a
better chance for showers and thunderstorms will loom on
Thursday into Friday given the close proximity of this boundary
to the area. Forecast temperatures drop a bit on Thursday, but
do remain seasonably hot as highs top out in the low/mid 90s
(80s across the mountains). After a slew of days with well above
average temperatures, eventually thunderstorm activity will
become more widespread. There should be a particular focus near
the boundary dropping toward I-70 on Thursday. While severe
weather is again possible on Thursday (Marginal risk), there may
also be a flash flooding component to some of these storms. The
main focus would be closer to the frontal zone where any west-
east oriented storms could train/backbuild. Will continue to
monitor that aspect of the forecast as additional guidance
arrives.

Storm chances likely linger into Thursday night as the reservoir
of instability is gradually exhausted. The rain cooled air over
the region should help usher temperatures down to more
seasonable levels for late June. The current forecast package
calls for low temperatures in the upper 60s to low 70s, locally
cooler in the higher terrain.

Uncertainty is fairly high heading into Friday as there are many
unknowns in where this backdoor frontal zone sets up. Often
relocated by convective processes, the current thoughts are this
boundary sits over the region on Friday. This would come with a
sharp north/south temperature gradient along it. While
northeastern Maryland could sit in the mid 70s, places south of
I-66 may be well into the 80s to near 90 degrees. Depending on
where this boundary ends up setting up, an additional risk of
severe thunderstorms and flash flooding would loom. For Friday
night, low temperatures are expected to stay fairly close to
readings from the night before.

&&

.LONG TERM /SATURDAY THROUGH TUESDAY/...
In wake of strong mid-level ridging the flow aloft turns zonal this
weekend through about the middle of next week as several subtle
shortwaves traverse the area. The Bermuda High builds toward the
western Atlantic during this time, helping to maintain moist
southerly flow into the Mid-Atlantic. Showers and thunderstorms are
in the forecast every day for the foreseeable future until we can
get a front to cross the area. Typical summertime temperatures in
the upper 80s to low 90s, with heat indices around 100 each day.
Muggy overnight temps in the low to mid 70s. Could see a few strong
to severe thunderstorms each day, with damaging downburst winds as
the main threat. Depending on mesoscale features and possible
passing of a shortwave trough aloft, there could be a day or two
with better chances for severe thunderstorms (looking possibly at
Saturday for this). Light steering flow could also produce a threat
for localized flooding some days.


&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
As the upper ridge slowly weakens, a return to daily shower and
thunderstorm chances returns to the forecast. Gradients do
remain light which will keep prevailing winds mainly at 10 knots
or less. Will maintain PROB30 groups at all terminals for late
this afternoon into the evening. These may be upgraded to
prevailing and TEMPO groups as confidence increases.

Shower and thunderstorm chances increase into Thursday and
Friday as a frontal zone to the north tracks near the region.
Expect periods of restrictions, particularly during the typical
afternoon/evening periods. This backdoor boundary eventually
moves through the area on Friday which should lead to mainly
easterly flow across the area.

VFR conditions prevail this weekend. Daily afternoon to evening
showers and thunderstorms are likely, and any of these could produce
brief periods of sub-VFR conditions.

&&

.MARINE...
As gradients remain on the weaker side, the chances for any
Small Craft Advisories are minimal through the remainder of the
work week. More notably, the threat for showers and
thunderstorms returns to the forecast which will pose a risk to
those out on the waters. While some storms are possible this
afternoon/evening, the coverage is expected to increase into
Thursday and Friday as a frontal system slowly pushes southward
across the waterways.

Winds remain light this weekend, with generally favorable marine and
boating conditions. However, showers and thunderstorms are in the
forecast each afternoon, and these could pose a threat to mariners
from gusty winds and lightning strikes.

&&

.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
northwesterly winds to help gradually lower anomalies over the
next day or so.

&&

.CLIMATE...
Here are some daily high temperature records during the June
25-26, 2025 timeframe:

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

                 ***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)

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Heat Advisory from 11 AM this morning to 9 PM EDT this evening
     for DCZ001.
MD...Heat Advisory from 11 AM this morning to 9 PM EDT this evening
     for MDZ003>006-008-011-013-014-016>018-502>508.
VA...Heat Advisory from 11 AM this morning to 9 PM EDT this evening
     for VAZ025>031-036>040-050-051-053>057-501-502-505-506-
     526-527.
WV...Heat Advisory from 11 AM this morning to 9 PM EDT this evening
     for WVZ050>053-055-502-504-506.
MARINE...Heat Advisory from 11 AM this morning to 9 PM EDT this evening
     for ANZ530.

&&

$$

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