826
FXUS62 KCHS 051802
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
202 PM EDT Sat Jul 5 2025

.SYNOPSIS...
Tropical Storm Chantal is forecast to approach the South
Carolina coast today and move onshore Sunday morning. High
pressure will rebuild into the area next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
All gridded and text forecasts have been updated to reflect the
11 AM NHC advisory on Tropical Storm (TS) Chantal. The TS Watch
may be upgraded to a TS Warning later today for the Charleston
County coast.

Today: The region will remain along the western periphery of
TS Chantal today as it meanders closer to the South Carolina
coast. Net moisture will slowly increase as the cyclonic
circulation around the system becomes better defined with PWATs
forecast to average 1.5-2.0". Convergence induced by the
strengthening northeast winds coupled with daytime heating could
support several bands of showers/tstms, especially across the
coastal corridor. 05/01z NBM hourly pops are likely too high
based on the latest set of CAMs, but no local modifications were
made given they do meet the national "break the glass"
criteria. The NBM scenario is one of several with CAMs along
with the 05/00z HREF supporting an overall drier solution,
especially over Southeast Georgia where subsidence and lower net
moisture values could limit shower/tstm coverage. Pops range
from 20-40% inland with 50-70% over the coastal counties. Highs
will range from the lower 90s across interior Southeast Georgia
where greater insolation will occur to the upper 80s along the
I-95 corridor with lower-mid 80s at the coast and beaches.

Breezy conditions will occur as deep layered mixing begins to
tap into higher winds aloft and the pressure gradient between
TD3 and inland high pressure tightens. North to northeast winds
will average 15-20 mph with gusts as high as 30-35 mph, highest
along the Charleston and Colleton County coasts. Gusts could be
higher on the elevated bridges around the Charleston and
Savannah Metro areas, as well as over the exposed and elevated
bridges/roads heading out to the barrier islands. These values
are just below Wind Advisory criteria. Winds on Lake Moultrie
will increase to 15-20 kt with gusts near 25 kt with waves 1-2
ft. Per coordination with WFO Columbia, a Lake Wind Advisory has
been posted for Lake Moultrie from 9 AM until 8 PM.

Tonight: Chantal is forecast to approach the South Carolina
coast through the night, making landfall just after daybreak
Sunday. TS conditions could occur along the Charleston County
coast with TS-force winds, mainly in gusts, occurring near the
immediate coast, beaches and possibly across the higher bridges
around the Charleston Metro area. Wind probabilities for
sustained 34 kt (TS) winds are currently averaging 15-30%. As
the system draws closer, the risk for showers/tstms will
gradually shift north into north coastal South Carolina through
the night with the Charleston Tri-County area likely seeing the
bulk of the rain with this system as drier air begins to wrap in
along the backside of the cyclone. This will result in a sharp
drop off of rain chances west of I-95. Pops range from 20-30%
across Southeast Georgia with 40-80% across Southeast South
Carolina, highest across eastern Berkeley County into upper
Charleston County. Lows tonight will range from the lower 70s
inland to the upper 70s at the beaches. Winds on Lake Moultrie
will remain elevated through the night and an extension of the
Lake Wind Advisory into the overnight hours may be needed later
today, but this will be highly dependent on the track and
strength of the tropical cyclone as it moves near the coast.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
Sunday: According to the latest NHC forecast, TS Chantal will
be positioned along the Charleston County coast Sunday morning.
During the day, it should take a northward track across eastern
South Carolina while weakening to a Tropical Depression.
Scattered showers and tstms will likely continue through Sunday
morning north of the Savannah River. Across southeast Georgia,
conditions look to remain relatively dry in the morning before
return flow finally pulls in deeper moisture southward and
instability increases in the afternoon. The threat for locally
heavy rainfall will be mostly limited to the Charleston Tri-
County given the potential for training cells. Gusty winds
should be less of a concern Sunday with a weakening system now
over land. The exception being some gusts 25-30 mph along the
Charleston County coast through the first half of the day.
Temperatures will be a bit stunted across southeast South
Carolina with highs in the mid to upper 80s, due to increased
cloud coverage and rainfall. However across southeast Georgia,
highs will reach around 90 degrees. Lows will bottom out in the
low to mid 70s.

Monday and Tuesday: Remnants of Chantal will continue to pull
northward away from the region, with the surface pattern to then
feature high pressure offshore with a trough of low pressure
inland. Shower and thunderstorm coverage will lessen (POPS
~20-30%), as the axis of highest moisture shifts northward. High
temperatures will jump back in the mid 90s Monday with more
sunshine in the forecast. A mild night is expected with min
overnight lows only in the mid to upper 70s. Tuesday currently
looks to be the hottest day during the upcoming week. With highs
forecast to approach the upper 90s, heat indices could make a
run for Heat Advisory criteria (108F degrees).

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Weak flow within subtle ridging aloft will persist along with
no discernible synoptic features. The forecast will be dominated
by a typical summertime sea breeze pattern, with scattered
showers and thunderstorms possible each day especially in the
afternoon and early evening when instability is maximized. Highs
are forecast to creep back up to the mid 90s inland of the
coast, with even higher heat indices.

&&

.AVIATION /18Z SATURDAY THROUGH THURSDAY/...
05/18z TAF Discussion:
In the northwest quadrant of TS Chantal, north-northeast winds
are sustained in the lower teens to lower 20 knots range, with
gusts of 20 to 30 knots. Radar is showing scattered rain bands
moving in from the northeast, and MVFR cigs across portions of
southeastern South Carolina improving into VFR range across
southeastern Georgia. As Chantal continues to slowly drift
northeastwards towards the South Santee River by daybreak
Sunday, expect scattered showers and isolated thunderstorms to
continue to remain possible, with winds remaining faily
consistent for the rest of the day. Winds decrease overnight as
the inversion attemps to set up, though gusts into the teens
will likely continue into the morning hours. MVFR cigs will
attempt to spread out across the region this evening, especially
across southeastern South Carolina where IFR cigs will also be
possible, with coverage uncertain for southeast Georgia.

Extended Aviation Outlook: Brief ceiling/vsby restrictions
possible Sunday through Wednesday due to scattered showers and
thunderstorms.

&&

.MARINE...
Per coordination with NHC and WFO Wilmington, the TS Watch for
the South Santee-Edisto Beach nearshore leg has been upgraded to
a TS Warning. A TS Watch remains in effect for the Charleston
Harbor and a Small Craft Advisory has been issued as well.

Update, the lower SC waters, AMZ352, was upgraded to a TS
Warning. The pressure gradient should increase this afternoon
into this evening, gusts may exceed 35 kts at times.

Today: Conditions across the waters will slowly deteriorate
today as TS Chantal draws closer to the coast. North to
northeast winds will reach 25-30 kt with gusts near 35 kt by
this afternoon along the South Santee-Edisto Beach nearshore
waters where a TS Warning is now in effect. The watch for
Charleston Harbor could be upgraded to a TS Warning later today.
Elsewhere, winds will be a tad lower with Small Craft
Advisories already in place. There is a chance TS conditions
could get into the Edisto Beach-Savannah nearshore leg,
especially over the northern parts, so a TS Warning may be
needed there depending on the strength and track of Chantal.
Seas will build through the day, reaching 5-8 ft this afternoon,
highest over the South Santee-Edisto Beach nearshore waters.

Tonight: Winds south of Edisto Beach will slowly diminish and
veer offshore as the center of TD3 moves into the middle-upper
South Carolina coast. Tropical storm conditions are the most
likely over the South Santee-Edisto Beach nearshore leg and
Charleston Harbor, but should occur through about midnight
before slowly diminishing as the highest winds shift north into
north coastal South Carolina. Seas will subside to 3-5 ft south
of Edisto Beach south, but hold 5-8 ft from South Santee River-
Edisto Beach.

Sunday through Thursday: Conditions will drastically improve on
Sunday as the flow briefly becomes offshore with the tropical
system located to the north. Winds will then settle into a SW
flow by Monday as high pressure rebuilds. Seas will remain
elevated across the Charleston County nearshore waters Sunday
before lowering to 3-4 ft by Monday. Elsewhere, seas 3-4 ft will
decrease to 2-3 ft by Monday night. No marine
concerns/headlines expected beyond Sunday.

Rip Currents: A high risk for rip currents is in place for all
beaches today due to a combination of increasing winds, building
swell and ongoing rip current reports from the various life
guard groups. A Moderate Risk for rip currents exists for all
area beaches on Sunday due to residual swell.

High Surf: Building northeast winds will push seas off the
Charleston County coast to 5-8 ft with local NWPS output showing
breaking waves of 4-6 ft occurring by this afternoon and
continuing through the night along parts of the Charleston
County beaches. The beaches of most concern are Kiawah Island,
Folly Beach, Sullivans Island and Dewees Island. A High Surf
Advisory has been posted from 2 PM until 8 AM Sunday.

&&

.TIDES/COASTAL FLOODING...
Tidal departures are expected to build today as northeast winds
increase ahead of TS Chantal. Tides could reach minor flood
thresholds in the Charleston Harbor with the late afternoon high
tide cycle. A Coastal Flood Advisory may be issued later today
for Charleston and Coastal Colleton Counties. There are no
concerns for coastal flooding along the remainder of the Georgia
or lower South Carolina coast.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...High Risk for Rip Currents until 8 PM EDT this evening for GAZ117-
     119-139-141.
SC...Tropical Storm Watch for SCZ050.
     High Risk for Rip Currents until 8 PM EDT this evening for
     SCZ048>051.
     Lake Wind Advisory until 8 PM EDT this evening for SCZ045.
     High Surf Advisory until 8 AM EDT Sunday for SCZ050.
MARINE...Small Craft Advisory until midnight EDT tonight for AMZ330.
     Tropical Storm Watch for AMZ330.
     Tropical Storm Warning for AMZ350-352.
     Small Craft Advisory until 6 AM EDT Sunday for AMZ354-374.

&&

$$

NEAR TERM...NED
SHORT TERM...
LONG TERM...
AVIATION...APT
MARINE...