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216
FXUS61 KAKQ 182032
AFDAKQ

AREA FORECAST DISCUSSION
National Weather Service Wakefield VA
432 PM EDT Wed Sep 18 2024

.SYNOPSIS...
Low pressure located over the Carolinas will weaken this evening,
and will move offshore tomorrow into Friday. A backdoor cold
front potentially drops back south across the region Friday
night through Saturday. High pressure builds north of the area
this weekend into early next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
As of 400 PM EDT Wednesday...

Key Messages:

- Additional showers today, with a few storms possible over
  southern sections. Any showers bringing the potential for
  locally heavy rainfall.

Latest analysis reveals high pressure just offshore of the New
England coast. The remnant low of PTC8 continues to weaken over
the western Carolinas. To the east, a well- defined baroclinic
leaf signature on VIS/IR satellite imagery offshore, where a
second area of low pressure continues to develop of the VA
Capes. This area of low pressure will continue to slowly develop
through the night and into the day on Thursday. Meanwhile, a
weak mesolow has developed just west of KAKQ, with some
localized flash flooding occurring across south central VA as of
this writing.

Deep-layer moisture still in place over the region (PW values
1.6-1.8") and some weak forcing for ascent along the westward
advancing coastal trough/remnant occlusion has resulted in
scattered to numerous showers along that convergence boundary,
with even a few isolated t-storms where MLCAPE values have
gradually increased through the early aftn and are now averaging
1000-1500 J/kg in MLCAPE per latest mesoanalysis across south
central VA into NE NC. CAMs have once again struggled a bit with
initiation, but are more or less on the same page with
continuing to push these showers SSW with time through the
afternoon toward far southern VA (I-58 corridor) west of
Franklin as we approach sunset.

Given minimal deep-layer shear and an otherwise rather moist
and (at best) marginally unstable airmass, thinking remains that
rain chances quickly decrease with loss of heating and taper
down further overnight. Remaining mostly cloudy to overcast with
saturated low-levels along the front likely portends another
night of low clouds late tonight and overnight (centered along
the theta-e ridge across the south), with areas of fog
developing late tonight over central and southern portions of
the area. Lows tonight drop back into the lower 60s NW to upper
60s SE.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/...
-- Changed Discussion --
As of 400 PM EDT Wednesday...

Key Messages:

- Decreasing rain chances Thursday and Friday.

As the coastal low lifts further to the NE on Thursday, expect a
drier day for most of the area compared to the previous few.
Expect some partial clearing (especially inland) late in the
day. Still, isolated to scattered afternoon showers or storms
are likely across southern Virginia into northeast North
Carolina (40-50% PoPs) as the weakening upper low pushes across
the Carolinas, with the closed low weakening and opening up by
Thu aftn. High temperatures on Thursday will generally be in
the upper 70s area-wide and low temperatures will range from the
upper 50s to lower 60s. Sunshine returns in earnest for Friday
with temperatures warming into the upper 70s along the coast to
low 80s inland. A backdoor cold front pushes south into the area
Friday night, bringing a slight chance for a late day/evening
shower over the MD eastern shore. Low temperatures Friday night
range from the upper 50s to the lower 60s.
-- End Changed Discussion --

&&

.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
As of 400 PM EDT Wednesday...

Key Messages:

- Drier and cooler weather arrives this weekend into early next
week.

Mainly cooler and drier into early next week. The upper trough
exits well offshore Monday into Tuesday. On its heels, broad
upper level ridging builds across the east coast into Atlantic
Canada and Greenland. At the surface, low pressure lingers off
the Mid-Atlantic coast through the weekend, gradually shifting
south Sunday into early next week. Meanwhile, high pressure
remains centered in Quebec through Saturday before dropping
south into New England by Monday. This looks to result in a
cooler period over the weekend into early next week, with highs
only in the low to mid 70s. Overnight lows will generally be in
the 50s away from the coast. Given the low offshore, coastal
areas can expect breezy conditions with gusts to 25-30 mph over
the weekend into Monday, along with greater cloud cover and
humidity. Should remain mainly dry, but we cannot rule out a
few isolated showers along the coast (20% PoPs) each
afternoon/evening.

&&

.AVIATION /21Z WEDNESDAY THROUGH MONDAY/...
As of 400 PM EDT Wednesday...

Widespread IFR to LIFR CIGs continue across the region this
morning. IFR CIGs likely try to hang on during much of the
daytime hours, with ECG having the best potential to see a
brief window of MVFR CIGs this afternoon. Additional showers
develop this morning through this afternoon, leading to the
potential for MVFR to IFR VSBY restrictions under any heavier
showers. Winds average 5-10 knots out of the NE through the
period. IFR to LIFR CIGs redevelop tonight and are expected for
the remainder of the forecast period.

Outlook: Sub-VFR CIGs likely stick around into early Thursday
afternoon, before a potential improvement late.  Gradually
improving conditions are then expected on Friday and Saturday.

&&

.MARINE...
As of 355 PM EDT Wednesday...

Key Messages:

- Small Craft Advisories continue for coastal waters off the
  Delmarva into Thursday.

- Another round of Small Craft Advisory conditions appears
  increasingly likely this weekend into early next week.

An elongated area of low pressure has developed from Northeast
North Carolina to off the Virginia Capes this afternoon as the
upper level trough over South Carolina slowly begins to lift
northeastward. Gradually, this area of low pressure will become
more defined well off the Delmarva and NJ coast on Thursday. In
the interim, expect conditions to remain rather unchanged with
N to NE flow in the 10 to 15 kt range on the Ches Bay and
Northern Coastal waters and 5 to 10 kt across the adjacent NC
waters. Seas remain elevated from the long time of NE flow
earlier in the week, but are coming down with seas from the
Mouth of the Bay southward in the coastal waters are in the 3 -
4 ft range. Farther north they are slower to drop and are still
in the 4 -7 ft range. So have maintained the SCA for this area
and actually extended the SCA through mid day for the northern 2
coast zones.

By Thursday afternoon, the area of low pressure should be coming
more organized, but will also be relatively stationary a couple
hundred miles off the NJ coast. This will allow for NNW winds to
persist for several days through Saturday. Generally winds
should remain mostly 10 - 15 kt through the period with maybe a
slight increase across the northern coastal waters for Friday
night. But overall, think most areas will stay below SCA levels
through Saturday.

By Saturday night, the coastal low finally begins to move and
actually drops SE heading toward Bermuda. But is it leaves, it
will begin to strength and the winds across the waters will
increase out of the NE with building seas once again. SCA
conditions look likely across the area waters from Sunday
through early next week as the seas jump up into the 5 - 8 ft
range into Tuesday before conditions relax with high pressure
building over the area waters.

&&

.TIDES/COASTAL FLOODING...
-- Changed Discussion --
As of 435 PM EDT Wednesday...

Astronomical tides will continue to increase with the approach
of the next full moon. Higher astro tides along with prolonged
onshore flow will continue to produce nuisance to low-end minor
tidal flooding across much of the area along the bay and tidal
rivers through the end of the week. Have issued another round of
Coastal Flood Advisories through the next high tide cycle
tonight through early tomorrow morning for most of the bay and
adjacent tributaries along with the coastal locations across the
VA portion of the Delmarva.

Additional advisories/extension of Advisories will likely be
needed through the end of the week and into the weekend due to
extended periods of onshore flow and high astro tides. Low end
moderate flooding is possible at particularly vulnerable spots
(Bishop`s Head, Oyster), but otherwise staying within minor
flood thresholds so far. However, a building flood tide
Saturday into Saturday night does bring the potential for tide
levels reaching moderate Coastal Flood Thresholds (best chances
northern coastal zones and lower bay) for tide cycles over the
upcoming weekend.
-- End Changed Discussion --

&&

.AKQ WATCHES/WARNINGS/ADVISORIES...
-- Changed Discussion --
MD...Coastal Flood Advisory from midnight tonight to 6 AM EDT
     Thursday for MDZ021>023.
NC...None.
VA...Coastal Flood Advisory until 5 AM EDT Thursday for VAZ075-077.
     Coastal Flood Advisory from 10 PM this evening to 3 AM EDT
     Thursday for VAZ078-085.
     Coastal Flood Advisory from 8 PM this evening to 1 AM EDT
     Thursday for VAZ084-086-095>098-523>525.
     Coastal Flood Advisory from 8 PM this evening to 2 AM EDT
     Thursday for VAZ099-100.
MARINE...Small Craft Advisory until 1 PM EDT Thursday for ANZ650-652.
     Small Craft Advisory until 4 AM EDT Thursday for ANZ654.
-- End Changed Discussion --

&&

$$

SYNOPSIS...AJB
NEAR TERM...MAM
SHORT TERM...MAM
LONG TERM...AJB/MAM
AVIATION...AJB/MAM
MARINE...ESS
TIDES/COASTAL FLOODING...ESS