954
FXUS61 KLWX 150800
AFDLWX

Area Forecast Discussion
National Weather Service Baltimore MD/Washington DC
400 AM EDT Sun Sep 15 2024

.SYNOPSIS...

High pressure to the northeast will continue to impact the area
through Monday. An area of low pressure off the southeastern
U.S. coast is expected to move northwestward or northward toward
the Carolinas early this week potentially bringing heavy rains
and coastal flooding Tuesday into Wednesday.

&&

.NEAR TERM /THROUGH TONIGHT/...

Low clouds have formed early this morning generally south of
Quantico to Fredericksburg and along the shoreline of Calvert
County on onshore flow. The low clouds will mix out in the late
morning, but there will more high clouds than yesterday. Still
mostly sunny skies are expected in the late morning and
afternoon. High temps will be a couple of degs cooler than
yesterday due to a more northeasterly wind trajectory.

High clouds will advance northward tonight and become denser,
particularly across southern areas. Also, expect more widespread
low clouds late tonight/early Monday as compared to today.
Overnight temps will remain mild due to increased cloud cover.

&&

.SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/...

High pressure will continue to hold through Monday evening
keeping the area dry through midnight Monday night. However,
high clouds will continue to advance northward and thicken
through the day resulting in mostly cloudy/overcast conditions
in the afternoon.

Low pressure off the southeast coast is expected to begin moving
inland late Monday night/Tue morning. Expect initially
stratiform light rain/drizzle by Tue morning as low-levels
saturate and sfc wedge erodes.

Forecast for Tue into Wed still largely depends on eventual
track of coastal low with NHC`s specialized regional and
consensus models indicating a track more across South Carolina
and the southern Appalachians and the more reliable ECMWF and
EPS guidance indicating a more northward track into our area Tue
night into Wed. Scenarions range from basically getting no rain
to seeing multiple inches of rain during the Tue-Tue night time
frame. At this time, some rain still appears likely Tue-Tue
night time frame, but how much rain falls and how impactful
would be is still to be determined yet.

&&

.LONG TERM /WEDNESDAY THROUGH SATURDAY/...

While its position is still uncertain, the surface low will likely
be weakening by Wednesday, while a closed upper low will be located
over the central Appalachians or Ohio Valley. Unless a dry slot can
wrap in, it appears rain will continue off and on through Wednesday.
Some thunderstorms are possible if the low takes a farther west
track and some instability is able to advect northward. For Thursday
through Saturday, surface features may be less defined, although
some guidance does suggest another low could develop near the coast.
By the weekend, surface high pressure will build across New England
(which could drive a backdoor front into the area) while upper
ridging amplifies toward the Great Lakes. This will force the closed
upper low to gradually drift southward. Between the upper low and
onshore flow, generally lighter showers will remain possible at
times. It`s possible drier air presses southward into the area over
the weekend behind the backdoor front, but is not guaranteed by any
measure.

Diurnal temperature ranges will remain muted thanks to the cloudy
showery weather, with highs a little below normal and lows a little
above normal. If the backdoor front can push through, cooling
temperatures would result next weekend.


&&

.AVIATION /07Z SUNDAY THROUGH THURSDAY/...

IFR cigs developing by 12Z Monday improving to MVFR/VFR Monday
afternoon. Rain moves in Tuesday with IFR cig restrictions
likely. Rain likely continues through Tue night before
diminishing Wed.

Sub-VFR ceilings are possible, if not likely, Wednesday and Thursday
as low pressure gradually weakens nearby. Showery weather will
continue but likely be lighter than Tuesday. A thunderstorm is
possible Wednesday depending on the position of the low.

&&

.MARINE...

SCA conditions will remain possible through Monday morning,
mainly across the southermost waters, then become increasingly
likely Monday night into Tuesday morning as gradient tightens in
response to approaching coastal low and high pressure to the
north. At this time, the risk of gale force winds appears low.

Low pressure will gradually weaken nearby Wednesday and Thursday,
with east to northeast winds continuing. Small Craft Advisory
conditions will remain possible, although there could be a period of
lesser winds depending on the position of the low and whether
another low forms off the coast. Showers will continue at times both
days, and a thunderstorm can`t be ruled out.


&&

.TIDES/COASTAL FLOODING...

Light but persistent onshore flow will cause water levels to
gradually rise over the next couple of days. Onshore flow
strengthens further Monday afternoon into Tuesday morning with
minor coastal flooding becoming increasingly likely by Tuesday
morning. Depending on the strength of onshore flow and the
track of low pressure to the south/southwest, near moderate
flooding may be possible at vulnerable shoreline locations late
Monday through Tuesday. However, at this time, all of the surge
guidance available only indicate minor flooding occurring.

&&

.LWX WATCHES/WARNINGS/ADVISORIES...
DC...None.
MD...Small Craft Advisory from noon today to midnight EDT tonight
     for MDZ008.
VA...None.
WV...None.
MARINE...Small Craft Advisory from noon today to midnight EDT tonight
     for ANZ530>532-535-536-538>542.
     Small Craft Advisory until 6 AM EDT Monday for ANZ533-534-537-
     543.

&&

$$

SYNOPSIS...LFR
NEAR TERM...LFR
SHORT TERM...LFR
LONG TERM...ADS
AVIATION...ADS/LFR
MARINE...ADS/LFR
TIDES/COASTAL FLOODING...