392
FXUS62 KCHS 091822
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
222 PM EDT Wed Jul 9 2025

.SYNOPSIS...
Weak high pressure will extend across the area through the
weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
This Afternoon: Latest radar imagery shows isolated to scattered
convection developing across the region. While the initial
development looks to stay confined to the sea breeze, will likely
see additional development spark this afternoon along outflow
boundaries and other mesoscale boundary collisions. In terms of
dynamics, soundings show ample instability (CAPE ~1000-2000 J/kg)
and PWATs near the 90th percentile (~2-2.5"). That being said,
overall shear and storm motion remain quite limited, suggesting
pulse type storms would be favored. In terms of hazards, would
expect frequent cloud-to-ground lightning to be possible, along with
damaging winds gusts and locally heavy rainfall. H-CAPE values over
1000 J/kg would also support an isolated threat of large hail to the
size of half dollars (1.25"). In addition to severe weather, this
environment would also support isolated flash flooding, especially
with any training storm. WPC`s latest ERO still supports a Slight
Risk across our area - with the greatest threat focused across our
interior counties and west of I-95. So, in terms of rainfall, have
totals upwards of 1-1.5" in the areas mentioned previously, with
some guidance even hinting at isolated pockets of 3 to 5 inches.
This could lead to areas of at least minor flooding, especially of
low-lying and poor drainage areas.

In regard to temperatures, latest observations across the region
show values ranging from the low to mid 80s along the coast to the
lower 90s in areas inland. Similar to yesterday, could see dewpoints
surge a bit near/behind the sea breeze as moisture pools, sending
values into the mid to upper 70s, with perhaps a few locations
nearing 80 degrees. As a result, should see heat index values remain
well below advisory level criteria, with values between 100-105
degrees.

Tonight: Convection will gradually wind down through the night
although the risk for isolated showers/tstms will likely persist
through daybreak Thursday. Lows will range from the lower 70s well
inland to around 80 at the beaches and Downtown Charleston.

&&

.SHORT TERM /THURSDAY THROUGH SATURDAY/...
Aloft, a large-scale ridge centered across the Atlantic will weaken
across the Southeast as h5 vort energy associated with a shortwave
tracks across the Tennessee Valley towards the Mid-Atlantic states.
At the sfc, the local area will remain nestled along the western
edge of an Atlantic high while troughing develops inland each day.
Although wind shear remains weak, there will be a small uptick in
low-lvl wind fields to support slightly more storm organization, but
also slightly faster storm motion, suggesting a greater threat for
strong and/or severe thunderstorms during the next few days, but
perhaps a more limited concern for minor flooding, although daily
PWATs around 2.0 inches should support brief heavy downpours with
convective activity each afternoon/evening.

Coverage of showers/thunderstorms should be greatest Thursday and
Friday (scattered to numerous), when peak h5 vort energy is draped
across a moderately unstable airmass residing near sfc troughing and
eventually an interacting sea breeze, although a more limited
isolated strong/severe thunderstorm risk could carry into the
weekend on Saturday with a noticeable downward trend in overall
convective coverage. Strong sfc heating supporting SBCAPE around
2000-3000 J/kg, low-lvl lapse rates between -7.5 to -8.5 C/km and
modest levels of DCAPE favor a damaging wind threat with
strong/severe thunderstorms Thursday afternoon/evening, and perhaps
again on Friday, with a lessor risk for small hail both days given
warm profiles/weak mid-lvl lapse rates. The latest SPC Day 2
Convective Outlook includes a Slight Risk for severe weather across
parts of Southeast South Carolina and Southeast Georgia on Thursday,
with a Marginal Risk for severe weather over remaining areas,
including the coast. WPC has also placed a Marginal Risk for
excessive rainfall across the far interior Thursday. On Friday, the
SPC Day 3 Outlook indicates a Marginal Risk for severe weather
covering far inland areas of Southeast South Carolina.

High temperatures will reach the upper 80s near the beaches to low-
mid 90s inland Thursday, then warm 1-2 degrees higher during the
weekend. A few spots could approach the upper 90s Saturday.
Overnight lows will remain mild, generally in the low-mid 70s inland
to upper 70s/around 80 at the beaches.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Ridging will continue to build over the Deep South late this weekend
and into early next week. Otherwise, little change expected in the
overall synoptic pattern and the forecast. Typical diurnal
convection will continue with scattered showers/thunderstorms
forming each day in the afternoon/evening. Sunday will be rather hot
as highs in the mid 90s could approach the upper 90s in some areas.
Heat indices could make a run for Heat Advisory criteria (108
degrees) in some spots, thus we will continue to monitor in the
event advisories are needed. Thereafter, temperatures will still
remain above normal, but highs will settle back into the lower
90s.

&&

.AVIATION /19Z WEDNESDAY THROUGH MONDAY/...
09/18z TAF Discussion: Scattered showers and thunderstorms continue
to develop across the region, currently impacting KCHS/KSAV. KJZI
looks to remain clear of this activity given the current placement
of the sea breeze, which is expected to continue its journey further
inland over the coming hours. As noted in the previous discussion,
should see a bulk of the showers/storms dissipate after sunset with
the loss of diurnal heating, allowing quiet conditions and VFR
levels to prevail for the remainder of the period. Otherwise, look
winds to remain out of south/southwest, with another round of
convection possible by the end of the TAF cycle.

Extended Aviation Outlook: Periods and/or TEMPO flight restrictions
are likely at CHS/JZI/SAV terminals Thursday/Friday afternoons and
evenings due to showers/thunderstorms impacting the area. Precip
coverage should become more typical Saturday/Sunday, posing a more
limited risk for TEMPO flight restrictions each day.

&&

.MARINE...
Through Tonight: Southerly winds continue to prevail, with some
slight backing noting as the sea breeze moves inland. Speeds will
generally range from 10-15 kt, but will be closer to 15 kt with
gusts to 20 kt near the land/sea interface and Charleston Harbor
near and behind the sea breeze. Otherwise, look for winds to shift
more southwesterly overnight, with seas averaging between 2-3 ft. As
noted previously, deep summertime nocturnal surging may cause winds
to become slightly stronger than forecast - though no headlines are
anticipated at this time.

Wednesday through Sunday: A fairly typical summertime pattern will
remain in place for much of the week with Atlantic high pressure
centered offshore and a weak trough developing inland each day.
Relatively benign conditions are expected across local waters as a
result, with south to southwest winds around 15 kt and seas between
2-4 ft through late week, subsiding to 1-3 ft by early next week. A
few gusts up to 20 kt are possible along the Charleston County Coast
and in the Charleston Harbor due to sea breeze influences.

&&

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

&&

$$

NEAR TERM...SST
SHORT TERM...DPB
LONG TERM...DPB
AVIATION...DPB/SST
MARINE...DPB/SST