393
FXUS62 KILM 180531 CCA
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
130 AM EDT Thu Jul 18 2024

.SYNOPSIS...
Shower and thunderstorm coverage will increase ahead of an
approaching cold front on Thursday and Friday. The front will
linger near or north of the area through the weekend. Rain
chances will remain elevated through Monday with temperatures
running near to slightly below normal. Unsettled weather may
continue into early next week.

&&

.UPDATE...
Had to bump up the hourly rain chances over the next few hours
with this line of showers and storms moving into the Pee Dee
region. Elsewhere, the Heat Advisory was allowed to expire at 8
PM EDT. Updated 00Z TAF discussion found below.

&&

.NEAR TERM /THROUGH THURSDAY/...
Forecast area remains between Bermuda High/5h ridge offshore and a
slow moving cold front/5h trough drifting southeast from the Upper
Midwest and Great Lakes. Deep southwest flow continues to pump
abundant moisture over the region, maintaining the heat and humidity
in the area through Thu. Precipitable water will remain above 2",
occasionally exceeding 2.25", through the near term with the
freezing level around 16k ft. This will lead to a very deep warm
cloud layer, creating the potential for efficient rain producing
storms both through the remainder of this afternoon into evening and
again Thu afternoon. Storm motion will be around 15 kt, so potential
for flooding is limited and would be in areas affected by multiple
storms in quick succession.

Storms thus far have been slow to develop, but with areas where
SBCAPE values are over 3500 J/kg expect to see storms thriving for
the next several hours, once they get going. Temperatures Thu
afternoon will be a bit cooler (outside of areas affected by storms
this morning), but will still support another round of afternoon and
evening showers and thunderstorms. The mid-levels may become
slightly more favorable for development, leading to storms
developing a bit earlier along the sea breeze, the Piedmont trough
and any lingering convective boundaries. Forecast soundings show an
increase in shear Thu compared to this afternoon, increasing
potential for a few strong to severe storms. Temperatures and
dewpoints will once again lead to heat index values right around
105. Another heat advisory may be needed to tomorrow afternoon.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
An abnormally unsettled period is expected as a mid-upper
shortwave trough pivots through New England with some trailing
vorticity reaching into the upper Mid-Atlantic region over
Thursday night into Friday. This will drive weak height falls
and a surface cold front down into the Carolinas, with the front
stalling out nearby or just to our north on Friday before
lifting back northward. The result will be scattered to perhaps
numerous showers and thunderstorms across the area on Thursday
evening and again on Friday. One possible limiting factor is
subtle height rises and weak subsidence during the afternoon and
evening on Friday that would keep coverage in the scattered
realm. Nevertheless, PWAT values around 2.25" will keep heavy
rainfall capable of producing flash flooding a concern, and the
Weather Prediction Center has highlighted the vast majority of
the region in a "slight" risk (threat level 2 out of 4) for
flash flooding over Thursday night and Friday. Although
effective shear will be weak to modest at best at our latitude,
a low threat for severe thunderstorms with damaging winds
produced by wet microbursts will be possible on Thursday evening
and again on Friday. After morning lows in the low-mid 70s,
high temperatures are expected to be limited by showers and
storms and their associated debris clouds, with highs in the
upper 80s expected by midday before storms get going.

On Saturday, mid-level ridging builds back in and pushes the
stalled front back north. With PWATs remaining around 2-2.2",
heavy rainfall will remain a concern, but overall coverage
should decrease somewhat as the surface front will be further
away. Nevertheless, mid-level impulses may be able to provide
subtle lift at the right time to enhance coverage during the
afternoon, or to produce storms northwest of our area which
could come down later in the day as a semi-organized line, but
it is difficult to forecast these impulses and their timing, so
PoPs are kept in the low likely range at this time. Similar
temperatures to Friday are expected, with morning lows in the
low-mid 70s and highs around 90F.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
With mid-level ridging and Bermuda high pressure dominating, a
return to a more typical summertime pattern is anticipated with
daily isolated to scattered convection each day. However,
guidance suggests that a mid-level shortwave or even a closed
low will dive into the central plains and send a stream of
impulses into our region for early next week. Depending on the
position of this shortwave and the timing and location of
impulses, we may see enhancements to the coverage of convection,
or these may be seen northwest of our area. Ultimately, PoPs
will remain above the climatological norm for the time being
until the evolution of this potential closed low becomes
clearer. Otherwise, with PWATs remaining in the 2-2.2" range
through the extended, heavy rainfall and localized flash
flooding will remain a concern with any thunderstorms.

Temperatures should remain near to slightly below normal (for
the first time in a while) as showers, storms, and debris clouds
keep us from seeing a full day of unrestricted heating. Thus,
highs around 90F and lows in the low-mid 70s are expected each
day.

&&

.AVIATION /06Z THURSDAY THROUGH MONDAY/...
VFR conditions occurring presently in the wake of earlier convection
though there is an abundance of debris cloud present over the area.
Some guidance indicates MVFR or even IFR BR/FG is possible before
daybreak.  Current thinking is debris clouds will prevent it but
should the debris clouds dissipate, br/fg could form.  After
sunrise, any fog that forms should rapidly burn off and generally
expect VFR cigs until showers and storms develop in the afternoon.
For now, have prob groups in the late afternoon with VCTS all
terminals into the evening.

Extended Outlook...Potential for afternoon and evening MVFR/IFR from
showers and thunderstorms through Monday.

&&

.MARINE...
Through Thursday...
Southwest flow 15-20 kt with higher gusts will continue tonight and
Thu as Bermuda High lingers off the coast. Marginal SCA remains in
effect for gusts 25 kt. Seas will remain 3-5 ft with a southerly
wind wave being the dominant wave. A southeast swell around 10
seconds will also be present.

Thursday night through Monday...
With Bermuda high pressure remaining in control of the low-level
flow, generally south to southwest winds will persist through
the period. Enhanced flow in the 15-20 kt range early in the
period will subside as the pressure gradient weakens over
Thursday night, leaving speeds in the 10-15 kt range through
Monday. Waves initially in the 3-5 ft range primarily due to
wind waves will subside into the 2-3 ft range for the remainder
of the period. Southerly wind waves will remain a constant
contributor while the southeasterly 8-9 sec swell looks to pick
up again with 2-3 ft swells returning for Saturday night and
beyond.

&&

.TIDES/COASTAL FLOODING...
Other - Rip Currents - Strong Longshore Currents:
Breezy southerly flow courtesy of a rather tight pressure
gradient between the inland trough and Bermuda high pressure
will lead to an enhanced rip current risk and moderate to strong
south- to-north longshore current through tomorrow.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
NC...Beach Hazards Statement from 6 AM EDT Thursday through
     Thursday evening for NCZ106-108.
     High Risk for Rip Currents from 6 AM EDT Thursday through Thursday
     evening for NCZ110.
SC...Beach Hazards Statement from 6 AM EDT Thursday through
     Thursday evening for SCZ056.
     High Risk for Rip Currents from 6 AM EDT Thursday through Thursday
     evening for SCZ054.
MARINE...Small Craft Advisory until 9 AM EDT Thursday for AMZ250-252-
     254-256.

&&

$$

SYNOPSIS...ILM
UPDATE...IGB
NEAR TERM...III
SHORT TERM...ABW
LONG TERM...ABW
AVIATION...31
MARINE...III/ABW