144
FXUS62 KCHS 241941
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
341 PM EDT Tue Jun 24 2025

.SYNOPSIS...
High pressure will largely remain across the Southeast U.S. Hot
and humid conditions are expected to continue with rain chances
increasing mid to late week as surface troughing begins to form
over the region and a few upper disturbances pass through.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
This evening and tonight: Satellite imagery shows a line of
towering cumulus along the coast from upper Charleston County
through the Grand Strand. On radar, there are a few showers
starting to show up and these will track off to the west or
dissipate. We could still see isolated showers or thunderstorms
into the early evening as the sea breeze gradually starts to
shift inland. The evening and overnight should again be quiet
with no significant fog concerns. Lows are forecast to mostly
range in the mid 70s, with upper 70s along the immediate coast.
There could even be a few low 70s across portions of southeast
GA. One potential low probability occurrence to keep an eye on
is for nocturnal convection across eastern NC to develop and
push to the southeast through the late night hours. If this
occurs, a few showers could approach the Santee River area
around sunrise Wednesday. Again, low probability but there are
some hints in hi-res model guidance.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/...
Wednesday: A strong upper level ridge over the eastern CONUS
will continue to hold Wednesday, along with the surface high
over the Central Atlantic. Models show a strong signal that a
MCS will develop over southeastern North Carolina in the
afternoon and move southwest toward Central Georgia, with
convection possibly tracking over our inland counties in the
evening. Impressive instability values are noted with MLCAPE
upwards of 2500 J/kg, mid-lvl lapse rates peaking around 8-9
degrees C/km, and DCAPE values in excess of 1200 J/kg, which
certainly fuel the possibility for strong to severe
thunderstorms to develop. Model soundings show slightly less
impressive values closer to the coast, but an unstable
environment nonetheless. Bulk shear is on the order of 15-20 kt,
which could lead to storms lacking organization, however
developing storms would have decently strong updrafts and
downdrafts. This leads us to the main threat which will be for
strong, damaging wind gusts, although hail cannot be ruled out.
We kept POPs maxed to only 30-40% with the majority of the
uncertainty stemming from the timing and overall evolution of
the MCS, which models tend to have trouble capturing.
Temperatures will once again climb to the mid to upper 90s, with
a majority of heat indices across the CWA peaking around
104-107 degrees. Although, a few spots across the Charleston
Tri-County could reach 108-109 degrees where the higher dew
points pool. Limiting factors include the possibility for
convection to arrive around the time of peak heating which would
disrupt temperatures, and deep mixing which would promote dew
points to drop into the upper 60s. Because conditions are
marginal with regards to meeting Heat Advisory criteria (108F),
there are no plans to issue one at this time, but we will
continue to monitor. Convection should come to an end overnight
with min temperatures reaching the low to mid 70s.

Thursday and Friday: The aforementioned upper level ridge will
begin to weaken slightly as it moves toward the Atlantic.
Remnant vorticity from an MCS over the Deep South, in addition
to a weak upper low across Florida, could provide forcing for
isolated to scattered showers and thunderstorms in the
afternoon/evening period both Thursday and Friday. Temperatures
will become a bit more muted with highs in the upper 80s to low
90s both days. Overnight lows Thursday will dip into the low to
mid 70s, nearing the upper 70s along the immediate coast.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Weak surface troughing inland will become more dominant over
the weekend, along with a mid level low over the FL Peninsula
and ridging to our northeast. This will lead to daily rain
chances through early next week, especially across southeast
Georgia. Temperatures will remain slightly above normal for this
time of the year.

&&

.AVIATION /20Z TUESDAY THROUGH SUNDAY/...
VFR conditions will prevail at KCHS, KJZI, and KSAV through 18z
Wednesday. Any isolated thunderstorms this afternoon are
expected to remain inland of the terminals. There is a better
chance of thunderstorms Wednesday afternoon, but likely beyond
the 18z TAF period.

Extended Aviation Outlook: Brief flight restrictions are
possible in the afternoon and evening hours within showers and
thunderstorms.

&&

.MARINE...
Tonight: Winds will peak early this evening along the land/sea
interface with the sea breeze, with speeds mostly in the 10-15
knot range. Overnight, winds should become more southwesterly
and diminish to be 10 knots or less. Seas are expected to
average around 2 feet through the period.

Wednesday through Sunday: South to southwest winds could become
a bit gusty each afternoon with gusts up to 15-20 kt as the
seabreeze develops (gusts strongest across the immediate coast
and Charleston Harbor). Otherwise, no marine concerns expected
through the period.

&&

.TIDES/COASTAL FLOODING...
Astronomical tides will peak around 6.5 ft MLLW at Charleston
with the evening high tide cycle this evening and Wednesday
night. Afternoon winds will only be marginally supportive of
increasing tidal departures each day. The evening high tide will
likely peak around 6.8-6.9 ft MLLW each evening, falling just
short of Coastal Flood Advisory criteria.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory until 8 PM EDT this evening for GAZ087-088-
     099>101-114>119-138.
SC...Heat Advisory until 8 PM EDT this evening for SCZ040-042>045-
     047>052.
MARINE...None.

&&

$$

NEAR TERM...BSH
SHORT TERM...BRS
LONG TERM...BRS
AVIATION...BRS/BSH
MARINE...BRS/BSH