119
FXUS62 KILM 262335
AFDILM

Area Forecast Discussion
National Weather Service Wilmington NC
735 PM EDT Thu Sep 26 2024

.SYNOPSIS...
Rain chances will increase through the day today with greater
impacts expected tonight into Friday morning as Helene passes
west of the forecast area. The primary threat will be dangerous
nighttime tornadoes with additional impacts from moderate to
heavy rain, gusty winds, and minor coastal flooding expected.
Cooler and drier high pressure returns into next week.

&&

.UPDATE...
For the early evening update I have increased pops for the next
few hours across South Carolina as well as QPF amounts. High
resolution guidance as well as the globals are insistent on a
lull or dry slot developing shortly but no sign of it at the
moment. Strong divergence aloft appears to be driving the
persistent activity. Turning to the tornado threat late tonight
through early to midday Friday...the situation remains
unchanged. A strongly forced very outer band (shown by the
guidance for several days) will move across the area from about
0800 UTC through about midday south to north. High resolution
guidance while meandering a bit shows several updraft helicity
swaths with the most favored area Cape Fear.

&&

.NEAR TERM /THROUGH FRIDAY/...
Unsettled weather will continue through Friday due to Helene.
Current conditions show stratiform rain over NE SC with embedded
heavier showers/storms. Scattered showers/storms are also in SE NC.
Some rotation has been seen in these stronger storms, but nothing
of concern has materialized in the area yet.

The predominant concern will be tornadoes tonight into Friday AM as
the main convective band moves through the area. The threat area
will be mainly near the coast and will largely follow the rain
bands. Some of these embedded stronger storms could also produce 50
kt wind gusts. Should rain bands start to train over the same area
we could see the risk for localized flooding, but rainfall totals
are still expected near 1-2 inches with locally higher amounts of +3
inches. For now the risk seems highest for our areas that received
high rainfall from PTC8 in Brunswick and New Hanover Counties. For
these areas, the soils are still mostly saturated, so it will take
less time for them to feel the impacts of continued rainfall.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY NIGHT/...
Large dry slot wrapping around the 5h low/Helene remnants combo
continues to spread over the local area Fri night and Sat. Later Sat
into Sat night, as the 5h low starts to drift east-northeast, some
of the deep moisture wrapped into the low will work its way over the
forecast area. This will lead to an increase in cloud cover Sat
night, but does not translate into an increase in rain chances. The
presence of deep dry air coupled with a bit of mid-level stability,
associated with the dry slot, will limit rain chances. An isolated
shower is possible along the immediate coast. Temperatures will run
above climo with lows some 10-15 degrees above.

&&

.LONG TERM /SUNDAY THROUGH THURSDAY/...
Low pressure aloft, the system that absorbed Helene, will slowly
move east across the Mid-Atlantic states Sun through Mon night. The
trough axis shifts offshore early Tue, setting up an northwest flow
aloft for the middle of the week. The proximity of the 5h low will
keep rain chances in the forecast Sun and Mon afternoons, although
coverage will be limited with best chances across NC. Tue will be
the transition day between the exiting 5h low and somewhat unsettled
conditions(Sun/Mon) and the deep northwest flow aloft and dry/fair
weather(Wed/Thu). Tue has some potential for limited rain chances in
the afternoon, although guidance has been trending drier. There may
be some lingering tropical moisture Tue, but with drier air and high
pressure moving in a solution with lesser coverage seems
appropriate. Temperatures above climo Sun/Mon will trend toward
climo for the middle of next week.

&&

.AVIATION /00Z FRIDAY THROUGH TUESDAY/...
Similar to other tropical events...convective bands will drive
MVFR to even a handful of IFR observations for the next 12 to
18 hours basically at all sites. Used lower end MVFR conditions
to address with the caveat that if a more pronounced/persistent
band develops will need to amend down to IFR.

Extended Outlook... VFR should return through the weekend under
high pressure.

&&

.MARINE...
Through Friday...Hazardous marine conditions expected through the
period due to Helene with worst conditions expected over the SC
waters. Infrequent gusts to Gale force may be possible with the
convective band over the NC waters as well more towards Friday
morning. Later forecast updates could raise a Tropical Storm Warning
for the NC waters if it`s deemed necessary. Otherwise, waterspouts
will also be a concern as the convective band moves through, mainly
tonight into Friday AM. Waveheights will be +10 ft come Friday
morning where they`ll linger through the rest of the day.

Friday night through Tuesday night...Small craft will be
ongoing Fri night and will continue into Sat morning before seas
drop below SCA thresholds. Southerly winds will be under 20kt
Fri night, decreasing to around 10 kt Sat morning. Southerly
flow continues into the start of next week with speeds 10 kt or
less. Later Mon into Tue the flow becomes more westerly, but no
change in speeds. Seas will steadily fall in response to the
decreasing winds with 3-5 ft Sat falling to 3 ft Sun and 2-3 ft
Mon and Tue.

&&

.TIDES/COASTAL FLOODING...
Minor coastal flooding remains a threat for the next several
days, especially in NC. Minor flooding along the Lower Cape
Fear River will impact both sides of the river during the
afternoon high tides today. Onshore winds due to Helene are
expected to produce additional coastal flooding this evening
along the beaches as it moves northward from the Gulf of Mexico
through the southeastern US. Normal water levels should return
this weekend.

&&

.ILM WATCHES/WARNINGS/ADVISORIES...
NC...High Surf Advisory from midnight tonight to midnight EDT
     Friday night for NCZ106-108-110.
     Coastal Flood Advisory until 9 PM EDT this evening for NCZ107.
SC...Tropical Storm Warning for SCZ017-023-024-032-033-039-054>056-
     058-059.
     High Surf Advisory from midnight tonight to midnight EDT
     Friday night for SCZ054-056.
MARINE...Small Craft Advisory until noon EDT Saturday for AMZ250-252.
     Tropical Storm Warning for AMZ254-256.
&&

$$

SYNOPSIS...ILM
UPDATE...SHK
NEAR TERM...LEW
SHORT TERM...III
LONG TERM...III
AVIATION...SHK
MARINE...III/LEW
TIDES/COASTAL FLOODING...