476
FXUS61 KLWX 240745
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
345 AM EDT Fri May 24 2024

.SYNOPSIS...

A cold front will drop into the Mid-Atlantic tonight, then
return northward as a warm front Saturday afternoon. The front
will then meander north to south over the weekend, before being
overtaken by a much stronger cold front Monday night. High
pressure looks to build toward the area by the middle of next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...

An MCV currently over western WV near Huntington is expected to
track ewd across central VA today and generate showers and
possible t-storms this morning mainly south of US-50. Additional
shower/t-storm activity is possible in the afternoon across
southwest areas before shortwave ridging/subsidence builds in.

Should remain quiet tonight under mid-level subsidence.
Patchy dense fog is possible especially in areas that receive
rain.

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/...

Shortwave-ridging is now expected to hold through much of the
day Saturday keeping most areas dry east of the Blue Ridge
Mountains. We`ll have to watch potential convection upstream
over the OH Valley and lower Great Lks as it could try to make
it into the Appalachian region.

Model guidance continues to indicate further low-mid level
height rises through the day Sunday ahead of deepening trough
over the Upper Midwest. This should act to suppress convection
in most areas. However, isold mountain afternoon storms are
still possible.

Sunday night...There has been some significant change in the
model guidance compared to the past two to three days. Some
guidance is now indicating a potential squall line racing
through the area late Sunday night/early Monday morning.
Synoptically, models are showing strong height falls and 925-850
mb moisture advection into the area. So, something to watch
next couple of days since this scenario has lacked consistency
the past few days. A more substantial severe wx threat still
appears on track for Memorial Day.

&&

.LONG TERM /MONDAY THROUGH THURSDAY/...

A mid-level SW trough will pivot through the Mid-Atlantic on Monday -
Memorial Day - during peak heating bringing a sfc cold front to
the region, and change in airmass come Tuesday. A favorable
environment for SVR thunderstorms exist with some of the highest
instability forecast of the season thus far (2-3k of SBCAPE)
coupled with 35-45 kts of effective shear. Modest H5 height
falls during peak heating along with any terrain circulations or
bay breezes could result in thunderstorms. Machine-learning
guidance from the NSSL has ~30% probabilities of SVR wx (1"
hail, 50+ kts of wind, or tornado) within 25 miles of a point
across the CWA. Monday is definitely a day to monitor given the
overall synoptic environment and model output soundings, which
do show the potential for supercells. Also of concern is the
abnormally moist airmass, with model output PWATs of ~1.7-2"
across the CWA, which is ~150-200% of climo norms for late May.
This could result in a flood/flash flood threat. Will continue
to monitor over the next couple of days.

CAPE decreases significantly behind the front Monday, though a
passing SW trough could bring additional rain showers Tuesday into
Wednesday. Does not look like a washout either day.

Behind this wave, dew points will fall into 40s come next Thursday
with highs in the upper 60s to low 70s. This may be the least humid
day until September across the area.

&&

.AVIATION /07Z FRIDAY THROUGH TUESDAY/...

Sct t-storms possible near KCHO. Other TAF sites should only see
showers at best with BKN-OVC 060-080 cigs. Should remain dry Sat
and Sun with only isold convection.

By Monday, a cold front approaches from the west and may bring
strong to severe thunderstorms to the terminals through the
afternoon and evening hours before dissipating. A passing shower
Tuesday may cause a brief restriction.

&&

.MARINE...

SCA conditions are not expected until Sun night.

Those on the waters for Memorial Day Monday should have a way to
receive weather alerts, as strong to severe thunderstorms appear
likely during the afternoon/evening.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...None.
VA...None.
WV...None.
MARINE...None.

&&

$$

SYNOPSIS...LFR
NEAR TERM...LFR
SHORT TERM...LFR
LONG TERM...CPB
AVIATION...LFR/CPB
MARINE...LFR/CPB