324
FXUS62 KCHS 100557
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
157 AM EDT Thu Jul 10 2025

.SYNOPSIS...
Weak high pressure will extend across the area into early next
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Through This Evening: Another active day is expected across the
Lowcountry and Southeast Georgia this afternoon and evening as
the region becomes increasingly influenced by the cyclonic flow
associated with the longwave trough that filling over eastern
CONUS. Morning water vapor imagery showed what is left of the
Tropical Upper Tropospheric Trough (TUTT) that was over the
Bahamas Wednesday spinning just offshore the Georgia coast. This
feature will weaken and translate farther offshore as the day
progresses.

A shortwave embedded within the weakening longwave trough will
propagate across the Carolinas this afternoon/evening. Model
cross section show a well-defined corridor of deep UVVs spreading
east ahead of the shortwave which will interact with an
increasingly moist and unstable atmosphere to support another
round of numerous showers/tstms. Convection may be a bit delayed
compared to Wednesday owing to slightly higher convective
temperatures, but many areas are poised to see rainfall later
this afternoon and evening as convection spreads east and
eventually offshore. Given the favorable thermodynamic
environment, 10/01z NBM pops were nudged up a bit with high end
likely pops (around 70%) now advertised for all areas from
mid/late afternoon through the mid-evening hours. Highs today
will warm into the lower-mid 90s with dewpoints likely to mix
out sufficiently to keep heat indices roughly in the 98-103
range with localized values reaching as high as 105 where
dewpoints will pool near the sea breeze.

Severe Weather: Modified soundings show moderate to locally
strong instability developing this afternoon as temperatures
warm into to the 90s. MLCAPE values as high as 3000-4000 J/kg
are expected within a plume of PWATs well in excess of 2 inches.
Shear (0-6km) is forecast to quite a bit stronger compared to
the past few days, peaking around 20 kt during the afternoon
and evening hours. While the shear is marginal for organized
severe tstms, there will likely be several clusters of loosely
organized convective clusters that occur where mesoscale
processes dominate. Damaging winds from wet microbursts will
likely be the primary convective hazard, although WBZ heights
just above 11 kft and H-CAPE around 1200 J/kg could yield
isolated instances of hail up to 1.25". In addition to the wind
and hail threat, frequent cloud-to-ground/water lightning is
likely to occur. The window for severe weather looks greatest
from roughly 3PM-9PM.

Heavy Rain/Flooding: The region remains situated within a plume
of tropical moisture. PWATs are forecast to surge to 2.20-2.35"
by late afternoon as moist, deep convection begins to trek east
across the Lowcountry and Southeast Georgia. Forecast soundings
show freezing levels will be lower than the past several days,
likely in response to the passing shortwave aloft. Warm cloud
processes may be somewhat limited because of this, but convection
will likely remain efficient rain producers given the elevated
PWAT values in place. Storm motions look much more progressive
than 24 hours with the mean steering flow forecast to strengthen
as the day progresses. Thankfully, this should limit the flood
potential somewhat, but there could still be some localized rain
amounts that exceed 4" based on the latest HREF neighborhood
probabilities and ensemble localized probability matched mean
(LPMM) output. There will likely be areas of minor flooding,
mainly in low-lying and poor drainage areas. Flash flooding
seems unlikely at this time.

Overnight: Convection will gradually wind down through the
night, although a risk for at least isolated showers/tstms will
linger, especially at the coast. Lows will range from the lower
70s well inland to the upper 70s/near 80 at the beaches.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
The surface pattern will feature high pressure fixed offshore
and a weak trough of low pressure across the Appalachians. A
mid-level shortwave will push offshore the Carolina coast early
Friday as ridging gradually builds over the Gulf and eventually
centers over the Deep South by Sunday. There is no shortage of
moisture (PWATs ~2.1") with west southwesterly flow continuously
advecting Gulf moisture into the region. Some shear will
accompany a moderately unstable airmass Friday (0-6 km bulk
shear 15-20 kt and ~1500 J/kg MLCAPE) resulting in the
possibility for an isolated strong to severe thunderstorm.
Damaging winds would be the greatest concern with DCAPE values
800+ J/kg and favorable sounding profiles for wet microbursts.
Storms could again produce bouts of heavy rain/downpours due to
the high moisture content, but should have enough movement to
limit flooding concerns.

Beyond Friday, the area will start to see a slight downtrend in
moisture advection Saturday night into Sunday as the "blocking"
ridge becomes centered over the Deep South, noted by PWATs
decreasing to 1.8 inches. However, enough moisture will be
present for the development of isolated to scattered showers and
thunderstorms both Saturday and Sunday, again mainly in the
afternoons and evenings.

A slight warming trend will continue through the short-term
period, thanks to the building upper ridge. Friday`s forecast
features max temps in the low to mid 90s, and about a degree or
so warmer for Saturday. By Sunday, highs in the mid 90s will
approach the upper 90s in some areas. Peak heat indices Sunday
will range between 103- 106 degrees, just shy of our local Heat
Advisory criteria of 108 degrees. We will continue to monitor in
the event advisories are needed. Overnight lows both Friday and
Saturday night will remain in the low/mid 70s away from the
coast, and upper 70s at the beaches and Downtown Charleston.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
Ridging will continue to build over the Deep South early next
week, meanwhile an upper level low could develop across the
Caribbean and move toward the Southeast Coast by the middle of
next week. Typical diurnal convection will continue Monday with
scattered showers and thunderstorms forecast, and perhaps an
increase in coverage possible as we near the middle of next week
due to the potential disturbance aloft. Monday will follow with
another day of high temperatures largely in the mid to upper
90s along with dew points in the mid 70s. Heat Advisories could
be needed for some areas Monday. Above normal temperatures will
continue into the middle of next week.

&&

.AVIATION /04Z THURSDAY THROUGH MONDAY/...
10/06z TAF Discussion:
KCHS/KJZI/KSAV: Tstms are poised to impact all three terminals
again late this afternoon/evening as numerous showers and tstms
impact the Lowcountry and Southeast Georgia. Window of impacts
looks greatest between 21-00z at all sites and TEMPO groups
highlighting TSRA were maintained. There are signals that a more
concentrated area of convection could impact KSAV, so a more
aggressive forecast to TSRA may be considered with the 12z TAF
cycle, pending short term model trends.

Extended Aviation Outlook: Periods of flight restrictions are
likely at the terminals Friday afternoon/evening due to showers
and thunderstorms impacting the area. Precip coverage should
become more typical over the weekend, posing a more limited risk
for flight restrictions.

&&

.MARINE...
Through Tonight: A south to southwest flow regime will prevail
through tonight as high pressure holds well offshore. Winds will
generally remain 15 kt or less, but could be as high as 15 kt
with gusts to 20 kt near the land/sea interface and Charleston
Harbor this afternoon as the sea breeze moves inland. Seas will
average 2-3 ft. Clusters of strong to severe tstms may move
offshore this evening and pose a risk for wind gusts in excess
of 34 kt, frequent cloud-to-ground lightning and vsbys less than
1 NM in locally heavy rainfall. Special Marine Warnings may be
needed.

Friday through Tuesday: A fairly typical summertime pattern
will remain in place with Atlantic high pressure centered
offshore and a weak trough developing inland nearly each day.
Relatively benign conditions are expected across the local
waters as a result, with south to southwest winds 15 kt or less
and seas between 2-4 ft, dropping to 1-3 ft late this weekend.
Gusts up to 20 kt are possible along the coast and in the
Charleston Harbor due to sea breeze influences each afternoon.

&&

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

&&

$$