788
FXUS62 KCHS 111042
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
642 AM EDT Fri Sep 11 2026

.WHAT HAS CHANGED...
All sections have been updated.

&&

.KEY MESSAGES...
- 1) Scattered showers and thunderstorms will continue to impact
  portions of southeast Georgia and southeast South Carolina
  each day through the weekend.

&&

.DISCUSSION...
KEY MESSAGE 1: Scattered showers and thunderstorms will
continue to impact portions of southeast Georgia and southeast
South Carolina each day through the weekend.

Today: Aloft, the setup will feature ridging centered off to
the east over the southwest Atlantic and a trough across the
lower MS Valley. This will place the forecast area within the
southwest to west-southwest flow between these two features. At
the surface, subtropical high pressure over the Atlantic will be
the main feature which will extend back to the west and into
the Southeast coast. The result will be a pretty common
summertime pattern with diurnal convection developing along
differential heating boundaries and the sea breeze. Model
guidance is in pretty agreement for scattered convective
coverage with initiation occurring in the early afternoon hours.
Soundings suggest an environment with MLCAPE values up around
2,000 J/kg and DCAPE values as high as 700-800 J/kg. Overall,
this is not a particularly interesting setup for severe
thunderstorm potential, but there could be an isolated strong to
marginally severe storm. Precipitable water values are expected
to up around 2.25 inches which would be in excess of the 90th
percentile and near the daily max for 11/12z on SPC`s Sounding
Climatology. This available combined with storm motions of 10
knots or less will yield a locally heavy rainfall threat. The
11/00z HREF suggests probabilities of 1" or more in 3 hours in
the 50-70 percent range at times, with 10-30 percent
probabilities of 3" or more in 3 hours. So, the main concern for
the day will be locally heavy rainfall. There isn`t much
confidence in identifying one area versus another for where the
heavy rainfall risk is highest, but there is good agreement for
the best coverage to be just inland of the immediate coast.
Thunderstorm coverage will gradually wane through into the
evening.

Weekend: The mid-levels will consist of weak ridging in the
western Atlantic, gradually dissipating. Meanwhile, a weak
trough over the Lower MS Valley Saturday morning will shift
eastward, moving over our area Sunday morning, then offshore by
Sunday afternoon. There will be some energy embedded ahead of
and within this trough. At the surface, High pressure will be
far in the Atlantic. Meanwhile, there should be a weak
stationary front to our north and weak surface troughing over
the Southeast U.S. Southwesterly flow will usher deep moisture
into our region. PWATs should easily be above 2". This is well
above normal per CHS sounding climatology and about 2 standard
deviations per NAEFs. The combination of mid-level lift, the
nearby front and surface troughing, along with the abundant
moisture will lead to an unsettled weekend. Models are generally
in good agreement with the precipitation coverage. Likewise,
the NBM has chance to likely POPs this weekend, and these may
need to be raised even further. The highest POPs will be in the
afternoons, moreso on Saturday compared to Sunday. Even though
high temperatures will be a few degrees above normal, there
isn`t a large amount of instability. DCAPEs may struggle to get
to higher values. So while a strong to marginally severe
thunderstorm cannot be ruled out each day, the main threat will
be heavy rainfall. While there is the concern for training and
backbuilding resulting from the mesoscale flow, there may be
just enough storm motion each day to limit significant flooding.
HREF and PPP probabilities for heavy rainfall aren`t very high
despite the PWATs, and WPC doesn`t have our area highlighted in
the ERO at this typing. Either way, there is the potential for
at least minor flooding in low-lying and poorly drained areas.

&&

.AVIATION /12Z FRIDAY THROUGH TUESDAY/...
The 12z TAF period begins with VFR conditions at KCHS, KJZI,
and KSAV. The main forecast challenge concerns afternoon
thunderstorm activity. Current thinking is that storms will
begin along the sea breeze in the early afternoon near KCHS and
KJZI. PROB30 groups are in place at both site generally in the
period starting around 17-18z and ending around 20-21z.
Thunderstorms might arrive at KSAV a bit later into the
afternoon and the PROB30 group is in place there from 20-23z.
Late tonight, model guidance is hinting at some fog and stratus
potential. However, as of now, it appears the best chances for
fog and stratus will be inland of the TAF sites.

Extended Aviation Outlook: Periodic flight restrictions will be
possible during the weekend due to showers and thunderstorms,
especially during the afternoon hours. There is the potential
flight restrictions could occur again Monday and Tuesday
afternoons, again due to showers and thunderstorms.

&&

.MARINE...
Today through tonight: Southwest flow this morning will turn
more southerly for the afternoon and evening with the
development of the sea breeze. Wind speeds will mostly top out
in the 10-15 knot range, though a few gusts up to 20 knots will
be possible along the land/sea interface late this afternoon and
early this evening. Then overnight, winds will turn back to
being more southwesterly, mostly in the 10-15 knot range. Seas
are expected to average 2-3 feet.

The synoptic pattern will consist of High pressure far in the
Atlantic. Meanwhile, unsettled conditions in the form of weak
fronts or surface troughing will be over the Southeast U.S.
These conditions will persist through the weekend, with hints of
possibly lasting into the middle of next week. Despite this
unsettled pattern, sustained winds will generally be S to SW 15
kt or less through the weekend. Seas will average 2-3 ft. Winds
may ease on Monday, then ramp up towards the middle of next
week. Seas will also follow this general trend. We can`t rule
out Small Craft Advisories for some of our marine zones during
towards the middle of next week. Mariners should also be alert
for showers and thunderstorms through the weekend. Stronger
storms could produce frequent lightning, brief strong/gusty
winds, and heavy rain with reduced visibility.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...None.
SC...None.
MARINE...None.

&&

$$