-- Discussion containing changed information from previous version are highlighted. --
470
FXUS62 KILM 191035
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
635 AM EDT Thu Sep 19 2024

.SYNOPSIS...
A weak cold front and low pressure aloft will result in a
chance for showers and isolated thunderstorm today. Slightly
cooler and drier weather will accompany persistent north-
northeasterly winds from Friday through the weekend as high
pressure builds in from the north.

&&

.NEAR TERM /THROUGH TONIGHT/...
Mid-level trough axis lingering over the region today and an
abundance of deep moisture will lead to another round of diurnal
showers and thunderstorms. The location of the trough axis suggest
NC portion of the forecast area will see more of the action, but the
typical subsidence/dry air in the wake of a 5h trough never seems to
materialize. Mid-level lapse rates in forecast soundings are nothing
to write home about and there is no shortwave energy. On the flip
side there is nothing preventing deeper convection from developing
once surface based instability increases, especially if a weak sea
breeze can develop in the afternoon. Coverage on Wed was aided by
shortwave enhancement, which will be lacking today. Despite this,
still think coverage under the trough axis will be similar to
yesterday. High chance to likely along the southeast NC coast with
pop gradually decreasing south and east, ending up low chance to
slight chance across inland SC. Temperatures will near to slightly
above climo, but lingering cloud cover has the potential to disrupt
the temp forecast. Lows above climo tonight, but debris cloud will
determine how much above.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
A mid-level trough axis should be over or near the coastal
areas at the start of the period and will continue slowly
shifting into the western Atlantic as the upper high centered
over the Rio Grande evolves into an elongated ridge with its
axis nosing into the southeastern US. Meanwhile, a weak cutoff
low off the upper Mid-Atlantic coast is expected to keep the
troughing over the western Atlantic from shifting away. The end
result will be abundant dry air in the mid-upper atmosphere with
subsidence largely keeping showers at bay through the weekend.
Nevertheless, daytime heating combined with pwats around
1.5-1.6" and relatively weak subsidence could permit a few
brief, shallow showers to develop on Friday with little or no
rainfall accumulation. In addition, northwesterly flow aloft may
start to bring in impulses that could lead to shower activity
grazing northern portions of the CWA on Sunday, so this will
need to be monitored.

Temperatures should hold right around normal each day with highs
in the middle 80s and lows in the low-mid 60s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
The mid-level ridge axis looks to gradually shift overhead early
next week and then confidence in what happens thereafter drops
off significantly. A general trend appears to be the approach of
a trough and associated cold front, but differences on the
timing, magnitude, and southern extent of the trough are driving
low confidence. In addition, guidance continues to suggest that
some tropical system brewing in the Caribbean may have some
influence on the weather just beyond the end of the period. This
will need to be monitored closely in the coming days as run-to-
run consistency in the timing and location of this potential system
has been very poor both within any given model and across
models.

Otherwise, another high pressure wedge looks to bring a breath
of cooler air on Monday with temperatures dropping 2-4 degrees
for both highs (low 80s) and lows (low 60s) compared to over
the weekend. Temperatures should then slowly rise through
midweek as the ridge axis shifts overhead.

&&

.AVIATION /12Z THURSDAY THROUGH MONDAY/...
-- Changed Discussion --
Cloud cover and even a few light showers/sprinkles this morning
keeping all sites VFR. Generally light winds from the northeast
today with afternoon storms developing 19-20Z across NC then
expanding south into SC. Highest coverage of storms will be in
NC, but activity will bleed south across the border. MVFR/IFR
potential late in the TAF period, but as is the case this
morning, lingering debris cloud and boundary layer winds 5-8kt
will work to limit fog/stratus development.

Extended Outlook...MVFR/IFR possible Friday morning.
-- End Changed Discussion --

&&

.MARINE...
Through Tonight...
North to northeast flow develops today as surface high starts to
expand east. Weak enough gradient and possibly enough heating that
weak, but atypical east-northeast sea breeze is possible in the
afternoon. Gradient becomes a little more defined tonight with
northeast flow increasing from around 5 kt for much of the day to 10-
15 kt late tonight. Seas around 2 ft with the exception of 2 ft with
occasional 3 ft north and east of Frying Pan Shoals today. Seas
north and east of Frying Pan Shoals start to build late tonight with
3 ft becoming more widespread. Remainder of the waters will remain
around 2 ft. The easterly swell will continue to be the only
noticeable wave today. However, tonight a northeast wind wave will
start to develop, although the easterly swell will remain
dominant.

Thursday Night through Monday...
A general northerly to northeasterly flow will dominate through
the period on the backside of slow-moving low pressure located
well to our northeast which will then be replaced by a high
pressure wedge as the low moves further out to sea on Monday.
Speeds will generally favor 10 kts or so. Wave heights look to
stay in the 2-3 ft range with 4 foot waves possible in the outer
portions of the 20nmi coastal zones, especially for the NC
waters over Friday night into Saturday and again on Monday.
Easterly 10 sec swells will remain a key component of the wave
spectrum with generally 1-2 ft wind waves also contributing.

&&

.TIDES/COASTAL FLOODING...
High astronomical tides will once again lead to coastal flooding
with this morning`s high tide. Water levels will rise above the
minor flooding category for the beaches or downtown Wilmington.
Another round of advisories is expected with this evening`s high
tide.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
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NC...Coastal Flood Advisory until noon EDT today for NCZ106-108-110.
     Coastal Flood Advisory until 3 PM EDT this afternoon for
     NCZ107.
SC...Coastal Flood Advisory until 1 PM EDT this afternoon for
     SCZ054-056.
MARINE...None.
-- End Changed Discussion --

&&

$$

SYNOPSIS...ILM
NEAR TERM...III
SHORT TERM...ABW
LONG TERM...ABW
AVIATION...III
MARINE...III/ABW
TIDES/COASTAL FLOODING...