915
FXUS61 KLWX 180129
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
929 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 WEDNESDAY/...
Thunderstorms will continue across northwestern parts of the
forecast area this evening before dissipating after midnight.
Despite intense rainfall rates observed with some of these
storms, storms are moving at fairly good clip limiting rainfall
amounts and the flood risk. Low clouds and/or fog will likely
redevelop overnight north of the Potomac River. T-storms
tonight should stay generally north of US-50.

&&

.SHORT TERM /WEDNESDAY NIGHT 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 /02Z WEDNESDAY THROUGH SUNDAY/...

A stray thunderstorm at KMRB this evening. Otherwise, low clouds
and/or fog are expected to redevelop overnight.

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...
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...None.
MD...Flood Watch until midnight EDT tonight for MDZ003-004-501>503-
     509-510.
VA...Flood Watch until midnight EDT tonight for VAZ028-031-505.
WV...Flood Watch until midnight EDT tonight for WVZ050>053-055-
     501>504.
MARINE...None.

&&

$$

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