259
FXUS62 KCHS 050610
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
210 AM EDT Sat Jul 5 2025

...TROPICAL DEPRESSION THREE POISED TO STRENGTHEN TODAY AND
TONIGHT AS IT APPROACHES THE SOUTH CAROLINA COAST...

.SYNOPSIS...
Tropical Depression Three is forecast to strengthen to a
tropical storm today before moving onshore late tonight into
Sunday morning along the South Carolina coast. High pressure
will rebuild next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Today: The region will remain along the western periphery of
Tropical Depression Three (TD3) today as it meanders closer to
the South Carolina coast and possibly strengthens to a tropical
storm per the latest NHC forecast. 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: What could be Tropical Storm (TS) 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 20-30%. 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, a low-end
tropical storm 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 the tropical low pressure
system 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 FRIDAY/...
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 /04Z SATURDAY THROUGH WEDNESDAY/...
05/06z TAF Discussion:
KCHS/KJZI: Winds will increase after daybreak as the pressure
gradient between TD3 and inland high pressure tightens. Gusts in
excess of 25 kt seems likely at both KCHS and KJZI from daybreak
through the evening hours. Bands of showers are expected to form
along the coast as the depression draws closer and convergence
increases along the beaches. Expect a band of impact both
terminals by late morning so TEMPO groups for MVFR conditions in
TSRA were introduced in the 14-17z period based on the latest
high-res model data. A band of more consolidated shower/tstm
activity could impact both terminals this evening, but this
will dependent on exactly where TD3, possibly TS Chantal,
tracks. VCSH was highlighted from 02z for now.

KSAV: VFR with little, if any, direct impacts from TD3 offshore.
Gusty winds will occur by daybreak with gusts exceeding 25 kt by
late morning.

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

&&

.MARINE...
Today: Conditions across the waters will slowly deteriorate
today as TD3 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
Watch remains in effect. The watch will likely be upgraded to a
TS Warning later this morning. 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 TD3. 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 Tropical Depression Three. 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 from 8 AM EDT this morning through this
     evening for GAZ117-119-139-141.
SC...Tropical Storm Watch for SCZ050.
     High Risk for Rip Currents from 8 AM EDT this morning through this
     evening for SCZ048>051.
     Lake Wind Advisory from 9 AM this morning to 8 PM EDT this
     evening for SCZ045.
     High Surf Advisory from 2 PM this afternoon to 8 AM EDT Sunday
     for SCZ050.
MARINE...Tropical Storm Watch for AMZ330-350.
     Small Craft Advisory until noon EDT Sunday for AMZ352.
     Small Craft Advisory until 6 AM EDT Sunday for AMZ354-374.

&&

$$