583
FXUS61 KLWX 220109
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
909 PM EDT Tue May 21 2024

.SYNOPSIS...
High pressure will move offshore through Wednesday. A cold front
will approach from the Midwest late Wednesday, then cross the
northern Mid-Atlantic Thursday. The front will stall to the north
across Pennsylvania keeping the local area in a warm and humid air
mass through early next week.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
Storms that formed in response to terrain circulations over the
higher terrain in Pendleton, Grant, Hardy, and Highland
Counties earlier are slowly drifting eastward into Rockingham
and Augusta Counties this evening. SPC Mesoanalysis still shows
around 1000 J/kg of MLCAPE present in those locations, so these
storms may continue over the next 1-2 hours before eventually
dissipating prior to midnight. Elsewhere, dry conditions are
expected through the night. Remnant cloud debris associated with
these storms may linger through a good portion of the night,
but clearing is expected again prior to daybreak. Some patchy
fog can`t be ruled out in locations that saw storms this
afternoon and evening, especially if skies clear out. Winds will
remain light out of the south, and overnight low temperatures
are expected to be in the low to mid 60s for most.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/...
High pressure will continue to slide further east on Wednesday, with
approaching low pressure system centered just west of the Great
Lakes. This low and its associated cold front will continue to slide
further east Wednesday into Thursday. Unsettled weather will be
possible both Wednesday and Thursday.

For Wednesday, isolated to widely scattered showers and
thunderstorms will be possible during the afternoon and evening
hours. Cannot rule out a strong to severe thunderstorm, especially
along and west of the Blue Ridge where areas will be most separated
from the lingering subsidence as a result of the departing ridge.
Highs on Wednesday will rise into the mid to upper 80s. Cannot
completely rule out a few localized sites hitting 90 degrees.

A more potent setup on Thursday will be possible across the Mid-
Atlantic as a result of the approaching cold front. Timing continues
to be favorable for peak heating with moving through the area.
Increased instability parameters will allow for increasing showers
and thunderstorms. Some of these storms may be strong to severe in
nature. The main hazards for these storms will be damaging winds and
large hail. The best chances for any severe storms will be along and
south of I-66. Highs will be in the upper 70s to mid 80s for most
areas. The storms should begin dissipate by Thursday night with lows
tracking into the upper 50s in the mountains to the low to mid 60s
further east across the lower elevations.

&&

.LONG TERM /FRIDAY THROUGH TUESDAY/...
On Friday, shortwave energy aloft will be approaching
the area before traversing to our north Saturday afternoon. At the
surface, a frontal boundary will be draped south of the Great Lakes
will be pushed southward towards our area. This will leave the
region in the warm sector, leading to a prolonged period of
unsettled weather. The frontal boundary is set to sink over the area
on Saturday before stalling over the region throughout the long
term. Daily thunderstorms driven by diurnal heating and the nearby
frontal boundary are expected with warm and humid conditions leading
to the possibility of some storms being severe. Daily CAPE values
greater than 1000 J/kg and lapse rates greater than 6 C/Km are
expected each afternoon. While conditions are the most favorable on
Sunday with the highest levels of CAPE and steepest lapse rates,

Low pressure to our south will provide the area with plenty of
moisture on Friday. WPC has the southwestern portions of the
forecast area in a marginal risk for excessive rainfall on Friday
with locally heavy rain possible during storms.

High temperatures will be in the upper 70s to low 80s each day with
overnight low temperatures dipping into the mid 50s to mid 60s each
night. Temperatures cool slightly in the wake of the cold front
early next week.

&&

.AVIATION /01Z WEDNESDAY THROUGH SUNDAY/...
Prevailing VFR conditions will continue through the night. Some
patches of fog or low clouds are possible to the west of the
Blue Ridge late tonight, but not at any of the TAF sites.
Scattered showers and thunderstorms may develop Wednesday
afternoon and early evening, especially west of the metros. VCTS
has been introduced tomorrow afternoon at MRB, and may need to
be considered further south and east with future TAF issuances.
Otherwise, VFR is expected through Thursday morning. Sub- VFR
conditions are possible with potentially more widespread shower
and thunderstorm activity Thursday into Thursday night as a cold
front crosses. Winds will shift to northwest.

VFR conditions are expected at all terminals Friday and Saturday
with the exception of during precipitation and thunderstorms which
are expected each afternoon. Winds will be out of the south on
Friday before shifting to westerly Saturday afternoon.

&&

.MARINE...
Light SSE flow will continue through Thursday ahead of a cold front
passage during the day on Thursday. SCAs will be possible Wednesday
afternoon and evening with increasing pressure gradient in place.
There is a potential for a few showers or thunderstorms over the
waters late Wednesday. The threat increases Thursday as a cold front
approaches the waters later in the day. SMWs may be needed Thursday.

Southerly winds on Friday shift to westerly Saturday afternoon and
are expected to remain below SCA criteria.

&&

.TIDES/COASTAL FLOODING...
Anamolies will continue to be elevated this afternoon through the
overnight hours. Sensitive locations like Annapolis may reach minor
flood stage for the high tide cycle overnight tonight.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Coastal Flood Advisory from 2 AM to 9 AM EDT Wednesday for
     MDZ014.
VA...None.
WV...None.
MARINE...None.

&&

$$

SYNOPSIS...DHOF
NEAR TERM...KJP
SHORT TERM...ADM
LONG TERM...AVS
AVIATION...AVS/DHOF/KJP/ADM
MARINE...AVS/DHOF/ADM
TIDES/COASTAL FLOODING...LWX