504
FXUS61 KLWX 150006
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
806 PM EDT Wed May 14 2025

.SYNOPSIS...
An upper low will slowly drift northeastward toward the area
before shearing out into an open wave and lifting to our
northeast on Thursday. An area of low pressure will track toward
the Upper Midwest and western Great Lakes by Friday, before
tracking eastward across Quebec and Ontario this weekend.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Widespread showers arc from western MD southeast to the northern
neck of VA as of sunset. Embedded within this area is a cluster
of very heavy thunderstorms just northeast of Charlottesville VA
with embedded heavier (though smaller and more transient)
elements within this broader zone.

Activity will gradually spread northeastward through the
remainder of the evening. Looking at the heavy rainfall threat
some of the same areas in the lee of the north-central VA Blue
Ridge into the Shenandoah Valley may get hit again. Any
additional rainfall could lead to rapid water level increases.
The Flash Flood Watch was expanded northeastward slightly based
on near term guidance and trends, and extended until midnight.

Remnant showers will gradually lift to the northeast tonight
with low clouds and fog possible again. Lows will be in the mid
50s to mid 60s.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
The weakening trough axis and possible weak surface low will be
near the Chesapeake Bay Thursday morning. This means any
remaining showers northeast of the Potomac should pivot away
during the morning hours. More breaks of sun are likely by the
middle of the morning on Thursday. However, northeast MD could
see clouds and a few shower linger even into the early portions
of the afternoon. For those that do break out on Thursday, high
temperatures are expected to rise toward 80. Not a lot of
confidence in the precipitation forecast thereafter. Advection
of a high theta-e airmass will be approaching from the west.
Other than possible terrain lift, forcing is otherwise nebulous
through the day, especially with mid-level heights rising in the
wake of the trough passage. However, CAMs suggest some storms
may develop over the central Appalachians at a minimum. Given
steepening lapse rates (in both the mid and lower levels) and
increasing shear, some storms could be severe. However, again
referring to those rising heights, still lots of questions
about the coverage, and also the strength should anything get
going. SPC has added a Marginal Risk for severe for now.

The uncertainty theme continues Thursday night through Friday
night as possible upstream convection moves toward the area. The
airmass will be characterized by steep lapse rates and strong
shear, so storms may be able to maintain themselves. Depending
on how the airmass is modified by upstream convection, Friday
in particular could have a high end CAPE/shear parameter space
across the area. However, the atmosphere may remain capped with
little to no storm development. Hopefully this becomes clearer
with time. What`s more certain is that it will turn hot and
humid Friday, with highs well into the 80s and dew points in the
mid 60s to lower 70s.

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
An area of surface low pressure will track northeast across the
Great Lakes towards Quebec Saturday and Sunday with the associated
cold fronts pushing through the forecast area on Saturday. Showers
and thunderstorms are expected ahead of the frontal passage Saturday
afternoon. High temperatures will be in the upper 70s to upper 80s
for most with those at higher elevations staying in the upper 60s to
lower 70s. Overnight low temperatures will be in the 50s to mid 60s
across the area.

Conditions dry out overnight into Sunday as high pressure builds in
from the northwest. In the wake of the cold front, temperatures will
be noticeably cooler with high temperatures in the 60s to 70s for
most. Those in the southernmost portions of the area may reach the
low 80s. Dry conditions continue on Monday with high highs in the
60s and 70s across the forecast area.

Precipitation chances return Tuesday evening as another low pressure
system tracks from the central CONUS towards the Great Lakes. The
associated warm front lifts north towards the forecast area on
Tuesday, bringing a chance for showers and thunderstorms Tuesday
night.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Showers and a few thunderstorms will continue this evening,
generally progressing southwest to northeast. Thunderstorms are
most likely at CHO, but TS may be more scattered once they
reach the metro terminals. Showers may linger at BWI/MTN into
the night. Otherwise, expect a return to IFR to perhaps LIFR
ceilings after 3-6z (earlier at BWI/MTN). Light E to S winds
are expected through the TAF period. Additionally, could see
some patchy dense fog develop overnight. CHO, MRB and IAD seem
the most likely candidates for that.

Conditions improve to VFR on Thursday morning, at least for
everyone except BWI and MTN. The highest chance for an
afternoon/evening thunderstorm appears to be at CHO on Thursday,
but this is highly uncertain. By the afternoon, even BWI and MTN
should try to clear out. Have added some PROB30 groups in
tomorrow afternoon for thunderstorms at BWI, DCA, and IAD. This
is a very low threat at this time, again with highest chances at
CHO, but thought it was worthy of mentioning.

Sub-VFR conditions (ceilings or fog) may return to mainly
MRB/BWI/MTN Thursday night. There is also potential for one or
more rounds of showers and thunderstorms late Thursday night
through Friday night, but details remain very uncertain at this
time.

Sub-VFR conditions are possible on Saturday during showers and
thunderstorms. Southwest winds in Saturday morning shift to westerly
in the afternoon, gusting 15 to 20 knots. Winds shift to
northwesterly Sunday afternoon, gusting 15 to 20 knots.

&&

.MARINE...
South to southwest winds should remain sub-SCA through Thursday
Friday night. The main concern will come from thunderstorms,
although the timing, coverage, and strength of any storms is
very uncertain at this time. Storms aren`t likely to reach the
waters Thursday, but there is still a chance.

Southwest winds shift to westerly on Saturday afternoon with showers
and thunderstorms possible across the waters. Winds are expected to
near, but remain below SCA criteria both days.

&&

.TIDES/COASTAL FLOODING...
Georgetown will likely have some freshwater related flooding by
Thursday, and a Coastal Flood Warning is now in effect for this
threat. Current forecast brings Georgetown to Moderate for much
of the day on Thursday as a result of the freshwater influence
flowing down from the west.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...Coastal Flood Warning from 7 AM Thursday to 4 PM EDT Friday
     for DCZ001.
MD...Flood Watch until midnight EDT tonight for MDZ501-502-509-510.
VA...Flood Watch until midnight EDT tonight for VAZ025>031-036>040-
     050-051-053-055>057-501>508-526-527.
WV...Flood Watch until midnight EDT tonight for WVZ050>053-055-
     501>506.
MARINE...None.

&&

$$

SYNOPSIS...ADS/DHOF
NEAR TERM...ADS/DHOF/CJL
SHORT TERM...ADS/DHOF/CJL
LONG TERM...AVS
AVIATION...ADS/AVS/DHOF/CJL
MARINE...ADS/AVS/DHOF/CJL
TIDES/COASTAL FLOODING...CJL/DHOF