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889
FXUS62 KCHS 051955
AFDCHS

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

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

.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
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Tropical Storm Chantal located off the SC coast continues to slowly
move north, approaching the SC coast. The latest SPC mesoanalysis
indicates that PW values ranged from 2.3 inches along the coast to
around 2 inches inland. SBCAPE values remained limited by the cloud
cover and frequent showers, values ranged between 500-1000 J/kg,
with very little normalized CAPE. Given the FZL near 16 kft and
marginal instability, the mention of thunderstorms will be limited
to a SCHC. Using the 12 HREF guidance, PoPs will gradually increase
through this evening and tonight, especially across the CHS Tri-
county. High resolution guidance indicates that rain bands will
become larger and gaps between the bands decreases. HREF indicates
that values of 1"/3hrs will peak between 50-70 percent between
Charleston and the South Santee River around 6Z. In addition, values
of 3"/3hr across the same area will peak around 10 percent. Through
tonight, rainfall totals are forecast to range between 1 to 3 inches
across the CHS Tri-county, with the greatest values across Berkeley
and Charleston Counties near the Santee River.

The pressure gradient between Chantal and high pressure ridged
across the western Carolinas will peak this afternoon, then may
gradually decrease into the overnight hours. The pinched gradient
combined with mixing to 2-3 kft has yield gusty conditions across
the region, especially along the SC coast and adjacent Atlantic
waters. A Lake Wind Advisory will remain in effect until 8 PM. NHC
track and wind forecast for Chantal indicates that a band of strong
winds around the system`s center will approach the northern
Charleston County coast late tonight, bringing another round of
stronger winds closer to the track line. Please see NHC`s latest
advisory.
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&&

.SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/...
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Sunday: The latest NHC forecast has Tropical Storm Chantal making
landfall by Sunday 12Z/8AM EDT near the mouth of the South Santee
River, weakening to a Tropical Depression as it moves across
southwestern South Carolina. This will continue chances for
scattered showers showers, expanding southwards into southeast
Georgia throughout the morning as the TD continues to weaken. While
the threat has decreased slightly now that we`re dependent on wrap
around moisture making it around the surface low, precipitable water
values of 2-2.5 inches combined with repeated/training storms will
continue the threat of locally heavy rainfall. Otherwise, aside from
areas in northern Charleston county where winds will be a touch
stronger due to proximity to the weakening TS, expect winds to swing
around from west-northwesterly to south-southwesterly throughout the
day, with gusts into the teens. Highs in the mid 80s to lower 90s
are expected, with partly to mostly cloudy skies throughout the day.

Monday and Tuesday: As weak ridging occurs aloft, the remnants of
Chantal will continue to lose influence over the area. In addition
to the expected daily sea-breeze, some weak shortwaves propagating
through the southwesterly flow in the lower-levels will keep chances
for low pops in the afternoon hours. While shear remains weak and
there is a lack of strong forcing, chances for severe weather remain
low, though given 1000-2000 J/kg of CAPE the chances are non-zero.
Max temperatures for Monday are in the mid 90s, rising into the mid
to upper 90s on Tuesday, with heat index values getting closer to
the Heat Advisory criteria of 108 deg F.
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&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
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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 heat indices
in the lower to mid 100s.
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&&

.AVIATION /20Z SATURDAY THROUGH THURSDAY/...
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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 fairly consistent
for the rest of the day. Winds decrease overnight as the
inversion attempts 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.
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&&

.MARINE...
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Tonight, the pressure gradient between Chantal and high pressure
ridged across the western Carolinas will peak this afternoon, then
may gradually decrease into the overnight hours. NHC track and wind
forecast for Chantal indicates that a band of strong winds around
the system`s center will approach the northern Charleston County
coast late tonight, bringing another round of stronger winds closer
to the track line. Please see NHC`s latest advisory.

Tropical Storm Warnings are in effect for the SC nearshore waters
with a Tropical Storm Watch across the CHS Harbor. SC nearshore
waters should see NE winds 25-30 kt with gusts 40 kts through late
tonight. As Chantal tracks over the northern Charleston County
nearshore waters, winds around the center may strengthen with gusts
around 45 kts. As a result of the strong winds, seas will build
through the near term, reaching 8-10 ft across the Charleston
nearshore waters after midnight. Elsewhere, conditions will remain
with solid Small Craft Advisory conditions, featuring gusts around
30 kts and seas 6 to 7 ft. Wave heights within the CHS Harbor
between 1 to 3 ft.

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 remains in place for all
beaches through 8 PM this evening due to a combination of
strong 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, decreasing back to Low Risk on Monday.

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 today until 8 AM Sunday.
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&&

.TIDES/COASTAL FLOODING...
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For the 5 PM high tide in Charleston, based to trends in tidal
departures, we will lower the forecast to around 6.8 ft MLLW.
There are no concerns for coastal flooding along the remainder
of the Georgia or lower South Carolina coast.
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&&

.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...APT
LONG TERM...APT
AVIATION...APT
MARINE...APT/NED