846
FXUS61 KLWX 170751
AFDLWX

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

.SYNOPSIS...
A warm front will slowly lift through the area today bringing the
return of warm temperatures and thunderstorm chances to the region.
Temperatures continue to climb Wednesday with additional shower and
thunderstorm chances as a trough of low pressure passes through. The
heat and humidity remain Thursday along with the risk of severe
weather as a strong cold front crosses the region. Drier and less
humid Friday as hot high pressure builds for the upcoming weekend
and into the middle part of next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
The CAD wedge continues to hold this morning especially over central
MD and northern VA. Low clouds, fog, and drizzle continue in these
locations with passing showers further south and west into central
VA and western MD where the dissipating stalled front remains. A
ripple of shortwave energy looks to push toward the region from
eastern KY and West Virginia this morning aiding in the development
of additional showers while lifting what is left of the stalled
boundary back north as a warm front heading into the afternoon. Some
uncertainty remain in regards to the placement of the warm front
later this afternoon given the influence of high pressure off the
northern New England coast. With the high up to the north the
current hybrid CAD wedge will be hard to erode especially over
central and northern MD this afternoon and even into the early
evening hours. Areas further south toward northern and central VA,
and the Alleghenies will likely see the wedge erode away later this
morning and into midday with a few filtered breaks of sunshine
poking through. Areas that do see the sunshine will see an increased
chance for thunderstorm development this afternoon as instability
increases (i.e CAPE values of 500-1500 j/kg). 0-6 km shear values
look to increase as well between 30-40 kts favoring progressive
multicellular clusters and line segments heading into the
afternoon/evening especially in locations along and west of the Blue
Ridge. PWATS unfortunately will remain anomalously high with values
running anywhere between 1.8-2.1 inches. Even with progressive storm
motions current antecedent conditions and efficient warm rain
processes (i.e rain rates 1-2"+/hr) will yield continued concerns
for localized flash flooding. With all that said, a Flood Watch has
been issued from 11am today through 10pm this evening for locations
along and west of the Blue Ridge.

00z CAM guidance shows convective initiation over the mountains
around midday before bringing everything east toward I-81/US-15
around 2-5pm and toward the metros shortly thereafter between 4-7pm.
The highest flood concerns appear to be across northern VA, the
Shenandoah Valley, and the Alleghenies where repetitive flash flood
warnings/flood warnings have taken place over recent days. Rain
totals of 0.5-2" are possible in the watch area with localized
totals up to 5 inches under heavier storms. Current 3-6 hr FFG
guidance remains less than 1 inch over a large chunk of the area, so
it won`t take much for instances of flash flooding to occur. The
risk for severe weather is low, though non-zero as SPC maintains a
Marginal Risk (Level 1 out 5) much of the area outside of northeast
MD this afternoon and evening. Damaging winds and wet microbursts
look to be the main threat with storms today.

After several days of well below normal temps we finally return
close to normal temps for mid June with highs in the low to mid 80s
this afternoon. Locations along the MD/PA line (i.e northeast and
central MD) may run a touch cooler in the upper 70s as the wedge
will hold on through mid-afternoon. Lows will fall back into the
upper 60s and low 70s tonight as the warm front lifts through the
area. Any residual thunderstorm activity will come to an end
although low and mid level clouds will remain especially along and
north of I-66/US-50. Fog will also be concern with the moist airmass
overhead.

&&

.SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/...
More of the same can be expected Wednesday as the warm front lifts
further north of the area. This will allow hotter temperatures to
move in along with slightly drier conditions under the influence of
west to southwest downsloping flow. Current 00z CAMS and synoptic
guidance still hint on the threat of a few showers and thunderstorms
during the afternoon and evening hours Wednesday as an upper level
trough passes through. Highest probability of severe thunderstorms
looks to be west of the Alleghenies due the proximity of an
encroaching cold front and east of US-15 where subtle lift from the
departing trough/bay breeze interaction could take place. Elsewhere,
pop showers and thunderstorms are likely given the hot and humid
airmass in place. Damaging winds will once again be the primary
threat with any storms that form along with localized concerns for
flash flooding. 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.

The lead shortwave trough works east Wednesday night into Thursday
as the cold front approaches form 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.

An upper level trough pivoting across the Great Lakes region will
push a strong cold front 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. CAPE values
will increase to around 1500-2000 j/kg with steep low-level lapse
rates (7+ C/Km) and moderate bulk shear values of (30-50 kts). This
will lead to progressive multicellular clusters and line segments
across the region. Damaging wind gusts will be the main hazard with
any storms that form. The Storm Prediction Center has the forecast
area east of the Allegheny front in a 15% risk for severe weather on
Thursday afternoon. One wildcard will be westerly flow aloft. This
could disturb the coverage of storms especially as they push east of
the mountains. We`ll continue to monitor this threat as it evolves.

Any convection will come to an end Thursday night 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 MONDAY/...
The main theme of the Long Term period will be increasing heat.
Medium range model progs indicate a likelihood of several days of
90+ degree high temperatures, with some low end potential of hitting
100 particularly early next week. This is thanks to a large ridge
that will be building over the eastern CONUS. Although no large
scale troughs or fronts are expected to cross the region, small
disturbances rounding the ridge in the hot and increasingly humid
airmass could result in a risk for showers and thunderstorms late in
the weekend into early next week. Heat indices will be on the rise
as well during this time, with at least a small chance of the first
round of heat headlines for the season.

&&

.AVIATION /08Z TUESDAY THROUGH SATURDAY/...
Widespread IFR to LIFR conditions continue across the terminals this
morning as a maritime airmass remains in place. Low clouds continue
to prevail along with passing showers and areas of drizzle. CIGS
range between 400-900 feet within the corridor with vsbys bouncing
between 2-6SM. These vsby reductions are due largely in part to
drizzle/showers compared to fog. Passing showers and drizzle will
remain within the corridor through at least 14-15z/10-11am as a warm
front lifts northward through the region. This boundary should erode
away the residual maritime airmass in place resulting in a lifting
cloud deck heading in the afternoon, especially at terminals along
and south of a line from KMRB to KIAD/KDCA. Areas further north
toward KBWI and KMTN will likely hang in the maritime air longer
with subtle improvements after 17-18z/1-2pm this afternoon. MVFR to
VFR conditions are expected this afternoon and evening although
renewed shower and thunderstorm chances look to impact the
terminals. Have PROB30 groups in for the corridor terminals with a
focus on thunderstorm development between 20-24z/4-8pm. Temporary
sub-VFR reductions are likely during this time. 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-676/US-50 which will be closer to the warm
front as it slowly jogs north of the area. Winds today will switch
from east this morning to the south and southeast this afternoon at
less than 15 kts.

After a brief period of sub-VFR Wednesday morning, VFR conditions
look to prevail. 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
into Saturday with west to northwest winds 5-10 knots becoming
south.

&&

.MARINE...
Low clouds and some marine fog are possible this morning given the
moist airmass in place. Low clouds and will be slow to lift this
afternoon as a warm front lifts through the region. Sub-SCA level
southerly winds are expected over the waters on both today and
Wednesday. An SMW or two cannot be ruled out with scattered showers
and thunderstorms during the afternoon and evening hours. Highest
coverage for storms both days will be between 3-8pm.

SMWs are possible given thermodynamic and kinematic environment for
Thursday in any thunderstorm. SCA conditions likely return with cold
frontal passage Thursday into Friday. West to northwest winds are
expected Friday into Saturday, becoming southerly Saturday afternoon
at generally 10 knots or less.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Flood Watch from 11 AM EDT this morning through this evening
     for MDZ003-501-502-509-510.
VA...Flood Watch from 11 AM EDT this morning through this evening
     for VAZ025>031-036>040-050-051-053-501>508-526-527.
WV...Flood Watch from 11 AM EDT this morning through this evening
     for WVZ050>053-055-501>506.
MARINE...None.

&&

$$

SYNOPSIS...EST
NEAR TERM...EST
SHORT TERM...EST
LONG TERM...DHOF
AVIATION...DHOF/EST
MARINE...DHOF/EST