201
FXUS61 KLWX 171910
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
310 PM EDT Tue Jun 17 2025

.SYNOPSIS...
A warm front will lead the charge of increasing humidity, warmer
temperatures and thunderstorm chances through Thursday.
Thunderstorms could be strong to severe, especially Thursday
prior to a cold frontal passage. Drier and less humid conditions
Friday as hot high pressure builds for the upcoming weekend and
into the middle part of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Low clouds linger just east of US 15 in Maryland, east of I-270
and much of southern Maryland. These low clouds have restricted
heavy showers and thunderstorms from developing this morning
through midday along and to the east of these areas. Places to
the west of the aforementioned areas have either seen showers
and embedded thunderstorms or will see convection within the
next 2 hours. As the low clouds fade or lift later this
afternoon into this evening, showers and thunderstorms should
begin to move over the regions. Showers and thunderstorms have
the capability of producing torrential rainfall and damaging
winds. SPC has most of our region in a Marginal Risk for severe
thunderstorms. Also, WPC has our northwestern half of our region
in a Slight Risk for excessive rainfall. The Moderate Risk for
excessive rainfall just touches part of the western Maryland.
There remains a Flood Watch for possible Flash Flooding from the
Appalachian Mountains to Washington D.C. and just to the
northwest and to the southeast through later this evening. Rain
amounts through the remainder of this afternoon into tonight
could average 1 to 2 inches with isolated higher spots.
Temperatures will top out near average for mid- June.

As convection wanes after midnight, some low clouds and patchy
fog will return in many locations. There could still be some
isolated showers venturing across parts of the region. Lows will
be above average and hitting the upper 60s to near 70.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
As a warm front moves farther to the north Wednesday, much
warmer temperatures and increasing humidity expected widespread.
With an increase in instability, showers and thunderstorms are
expected during the afternoon and evening on Wednesday. The
higher chances of showers and gusty thunderstorms appear to be
in the Appalachians and along the Mason-Dixon region to near
I-81. A second area could be in eastern and southern Maryland
where a bay breeze interacts with a trough. Damaging winds will
once again be the primary threat with heavy downpours with any
storms that form. Highs Wednesday will push into the upper 80s
and low 90s outside the mountains. Heat index values Wednesday
afternoon will make it feel like the mid to upper 90s,
especially east US-15 as humidity continues to increase across
the region.

A shortwave trough works east Wednesday night into Thursday as
the cold front approaches from the Ohio River Valley. Convection
over the mountains will work east as well before slowly
dissipating given the lack of instability during the overnight
hours. Lows Wednesday night will fall back into the low to mid
70s.

A strong cold front will move through the area Thursday. High
temperatures will rise into the low to mid 90s Thursday
afternoon with heat index values in the metros near 100 degrees.
Multicellular clusters and line segments will move across the
region. Damaging wind gusts will be the main hazard. SPC has
the forecast area along and all areas to the east of the
Allegheny front in a Slight Risk for severe thunderstorms
Thursday afternoon. WPC has all of our Appalachian Front in a
Marginal Risk for excessive rainfall. Hence, heavy rainfall from
showers and thunderstorms could play a role in threats across
the region once again.

Any convection will come to an end late Thursday into Thursday
evening with lowering humidity in the wake of the frontal
passage. Lows Thursday night will fall back into the low to mid
60s. Areas of fog will remain possible near the water and in the
valleys.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
Strong upper level ridging builds over the Mid-Atlantic throughout
the long term period, leading to dry conditions and warming
temperatures. At the surface, high pressure builds over the eastern
CONUS through the weekend. High temperatures on Friday will be 80s
for most with those at higher elevations staying in the 70s. As
temperatures warm through the weekend, highs each day rise into the
low to mid 90s with only those along the highest elevations staying
in the 80s.

In addition to warming temperatures, dew points increase through
early next week leading to heat indices nearing or exceeding 100
degrees Sunday and Monday.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...
The low cloud deck continues to lift or retreat to the northeast
this afternoon into this evening as a warm front lifts to the
north. MVFR to VFR conditions are expected this afternoon and
evening. Heavy showers and any strong thunderstorms that move
over the terminals later this afternoon and evening could bring
a brief MVFR or IFR condition to the terminals. Storms will
pack a punch with damaging winds and localized flash flooding as
the primary concerns.

Periods of sub-VFR conditions are likely again overnight with
low and mid level clouds sticking around and areas of fog. This
is especially true in areas that do see the rain and locations
north of I-66/US-50 which will be closer to the warm front as
it slowly jogs north of the area. Winds will become south to
southeast at less than 15 kts.

After a brief period of sub-VFR Wednesday morning, VFR conditions
will return. Additional showers and thunderstorms during the
afternoon and evening hours will lead to temporary sub-VFR drops
especially at terminals east of the Blue Ridge. Overall
coverage will be limited with damaging winds and localized flash
flooding once again as the primary concerns.

Prevailing VFR conditions are expected Thursday. Temporary drops to
sub-VFR conditions may be possible in thunderstorms especially
Thursday afternoon and evening.

VFR conditions are expected Friday and Saturday across all
terminals as surface high pressure builds over the Mid-Atlantic.
Westerly winds on Friday shift to southerly on Saturday,
gusting blowing 5 to 10 knots each afternoon.

&&

.MARINE...
Sub-SCA conditions expected over the waters this afternoon and
then again on Wednesday into Wednesday evening. A few SMWs may
be issued with pending convection each afternoon. Low clouds
could form again overnight tonight, but not as much as last
night since the warm front will have lifted to the north.

SMWs are possible given thermodynamic and kinematic environment for
Thursday in any thunderstorm.

Westerly winds on Friday shift to southerly on Saturday. Winds
are expected to remain below Small Craft Advisory criteria both
days as surface high pressure builds over the forecast area.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Flood Watch until midnight EDT tonight for DCZ001.
MD...Flood Watch until midnight EDT tonight for MDZ004-013-503-504.
     Flood Watch until 10 PM EDT this evening for MDZ003-501-502-
     509-510.
VA...Flood Watch until midnight EDT tonight for VAZ054.
     Flood Watch until 10 PM EDT this evening for VAZ025>031-
     036>040-050-051-053-501>508-526-527.
WV...Flood Watch until 10 PM EDT this evening for WVZ050>053-055-
     501>506.
MARINE...None.

&&

$$

SYNOPSIS...EST
NEAR TERM...KLW/EST
SHORT TERM...KLW/EST
LONG TERM...AVS
AVIATION...AVS/KLW/EST
MARINE...AVS/KLW/EST