088
FXUS62 KCHS 041157
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
757 AM EDT Mon Aug 4 2025

.SYNOPSIS...
A stationary front will linger near the area this week as high
pressure remains centered well to the north. Low pressure could
develop off the Southeast U.S. coast Thursday into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Early Morning: A small area of low pressure will continue to drive a
cluster of showers with embedded thunderstorms near Edisto
Island, SC north-northeast across Southeast South Carolina coastal
communities during the next few hours, attempting to enter the
Charleston area by the end of the morning commute, before continuing
north and/or trending offshore mid-morning. Ample moisture
resides ahead of this activity (PWATS 2.25), suggesting similar
impacts/trends observed during the past couple hours. Higher
instability remains off the coast and much of the ongoing
convection should display a bit of weakening while entering
slightly more stable air, especially after drifting onshore.
Rainfall amounts between 1/4 to 1/2 inch are generally anticipated
with this activity. Although flash flooding is not anticipated,
conditions could support a Flood Advisory if shower duration is
longer over some areas than expected.

Today: Aloft, a weak mid-lvl trough will progress east across the
Midwest, favoring h5 shortwave energy to ripple across the Southeast
United States. At the sfc, high pressure will persist across much of
the local area while a front remains nearly stationary across
northern Florida. The setup will favor conditions quite similar to
those experienced the previous day, with ample moisture (PWATS near
2.25 inches) residing across much of the area, enhanced moisture
convergence near the coast, and weak isentropic lift/h5 shortwave
energy providing forcing to support scattered to numerous
showers/thunderstorms. Precip coverage should be largest during peak
diurnal heating hours this afternoon and perhaps persist into early
evening. Activity should initially be more focused across coastal
South Carolina areas this morning, before developing across inland
areas as h5 shortwave energy and weak isentropic lift shift/occur
across sfc high pressure. Although instability is rather meager
(especially inland) with high pressure supporting slightly
cooler conditions within a northeast sfc flow and storm motions
appear slightly faster than previous days, the abundance of
moisture and forcing could support bouts of heavy downpours with
showers/thunderstorms, and eventually require Flood Advisories
and/or Flash Flood Warnings for activity that resides over an
area for a longer duration. WPC currently has much of Southeast
Georgia in a Slight Risk for excessive rainfall, and Marginal
Risk extending north across coastal areas into Southeast South
Carolina.

Abundant cloud cover and persistent shower and/or thunderstorms
coverage will help keep afternoon highs a bit cooler this afternoon,
especially within the high pressure/northeast sfc flow pattern. In
general, high temps should range in the upper 70s well inland to low-
mid 80s across Southeast Georgia and along/east of I-95 across
Southeast South Carolina.

Tonight: Much like the previous few night, shower and thunderstorm
activity could linger into evening hours, but should gradually wane
with the loss of diurnal heating while the sfc high pressure pattern
remains in place. At the very least, the threat for heavy rainfall
potential should become more limited inland as instability is weak
within high pressure. However, given the abundance of moisture, few
to scattered showers remain possible into early morning hours.
Closer the coast, moisture convergence and modest instability across
the nearby Atlantic could support additional bouts of downpours with
showers/thunderstorms and the potential need for Flood Advisories
and/or Flash Flood Warnings overnight. Low temps should range in the
upper 60s inland to low-mid 70s closer to the coast.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
The anomalously strong high pressure wedge will hold for much of the
week as the region remains pinned between subtropical ridging
offshore of the Southeast U.S. and a filling longwave trough
extending from the Ohio Valley south into the lower Mississippi
Valley. Ribbons of vorticity ejecting north across the Southeast
U.S. ahead of the weakening longwave coupled with typical diurnal
instability and the nearby quasi-stationary wedge front just to
south/offshore will support numerous showers/tstms each day with the
greatest coverage occurring across Southeast Georgia.

Model cross sections suggest forcing/UVVs from these impulses will
not be overly deep or strong, but with a plume of high PWATs in
place (2.00-2.25") holding in place and fairly low convective
temperatures each day, it will not take too much for convective
initiation to occur. Convection each day will likely be largely
driven by numerous mesoscale boundary interactions, including
convective outflow boundaries and the afternoon sea breeze.
Convection will be slow to wane during the evening hours each day
with a risk for at least isolated showers/tstms lingering through
the night. The forecast becomes a bit more uncertain beginning
Thursday with low pressure possibly developing off the Southeast
U.S. coast. Afternoon highs (mid 80s to around 90) will remain
slightly below normal for early August given the considerable amount
of convection and debris cloud cover that will occur each day.
Overnight lows (upper 60s well inland to lower 70s at the coast)
will average at or just slightly below normal.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
Guidance is starting to show a slightly stronger signal that an area
of low pressure will develop off the Southeast U.S. coast by late in
the week into the weekend as a Tropical Upper Tropospheric Trough
(TUTT) propagating westward along the southern flanks of the
subtropical upper-level anticyclone over the central north Atlantic
approaches the Bahamas. Much of the forecast will hing on this
feature with its character, strength, timing and track still highly
uncertain. The National Hurricane Center currently shows a low
chance for tropical cyclone development. For now, the forecast
remain aligned with the 04/01z NBM, which keeps unsettled conditions
in place in the Friday to Sunday time period.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
CHS/JZI: VFR conditions should prevail through at least 06Z
Tuesday, but TEMPO MVFR cigs with showers are possible this
morning in the 12-15Z timeframe. Confidence is low in regards to
timing of additional showers and/or possibly thunderstorms
during the afternoon, but VCSH has been placed at the CHS
terminal between 19-23Z and JZI terminal between 19-01Z
today/tonight. JZI appears to have the higher potential for
flight restrictions late in the TAF period, with MVFR cigs
prevailing during the second half of tonight (06Z-12Z Tuesday).

SAV: MVFR cigs should prevail for a bulk of the taf period
today and tonight, but cigs could remain VFR temporarily in the
12Z-16Z timeframe this morning. Confidence is too low in regards
to timing to include additional shower and thunderstorm
activity at the terminal this afternoon/evening, but VCSH has
been included between 18Z-03Z. Future TAF adjustments will
likely be needed for convective trends.

Extended Aviation Outlook: An elevated risk for flight restrictions
from showers/tstms will persist for much of the week.

&&

.MARINE...
Today and Tonight: Overall, the setup remains similar to that
experienced the previous day with high pressure placed inland
and a nearly stationary front south of the local area. A
slightly enhanced pressure gradient across local waters supports
northeasterly winds around 15 kt with gusts around 20 kt
through the day, but the gradient is expected to weaken during
the afternoon into the evening, suggesting winds to lower to
10-15 kt and turn more east overnight. Seas will slowly subside
to 2-4 ft as winds weaken through the night.

Tuesday and Wednesday: There are no immediate high confidence
concerns. East to northeast winds will prevail for much of the
period as an inland wedge of high pressure prevails. Occasional
pinching of the pressure gradient is likely, but winds will
generally remain 15 kt or less outside of convection through
Wednesday. Seas will average 2-4 ft.

Thursday through Saturday: Much will depend on how strong low
pressure that could form off the Southeast U.S. coast gets. East to
northeast winds will continue, but speeds as well as waves/swell may
become enhanced depending on the eventual track, strength and speed
the low takes.

Rip Currents: Some elevated swell and continued northeast flow will
yield a Moderate Risk of rip currents for the GA beaches on today.

&&

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

&&

$$

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