998
FXUS62 KCHS 070953
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
553 AM EDT Mon Jul 7 2025

.SYNOPSIS...
Weak high pressure will extend across the area through the
week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Today: Subtropical ridging will build in from the east today as
deep-layered high pressure over the Atlantic strengthens. A
typical southwest flow regime will prevail with winds backing
near the coast with the afternoon resultant sea breeze. A plume
of tropical moisture characterized by PWATS 2-2.25" remains in
place in the wake of Tropical Storm Chantal and models indicate
net moisture values will change little today. The combination of
building instability and deep moisture will support a typical
deep summer diurnal convective pattern with rain chances peaking
in the mid-late afternoon hours, mainly ahead of the resultant
sea breeze. Pops range from 20-40% this afternoon consistent
with the 07/01z NBM and look reasonable per the latest HREF and
CAMs. Shear is low with in a relatively weak wind environment,
so convection will be slow moving with storm propagation likely
being dominated by convective outflows and other mesoscale
boundary collisions. Modified soundings are depicting a classic
airmass thermodynamic environment, so a pulse severe tstm or
two could occur with damaging winds from wet microbursts being
the primary hazard along with locally heavy rainfall and
frequent cloud-to-ground lightning.

It is going to be a toasty day across the the Lowcountry and
Southeast Georgia with warming 850 hPa temperatures of 18-20C
and 1000-850 hPa thicknesses of 1425-1440 meters supportive of
highs in the mid-upper 90s inland. At the coast, temperatures
will be augmented by the timing of the afternoon resultant sea
breeze circulation which will tend to curtail temperatures
somewhat. Highs at the beaches will peak in the mid-upper 80s.
Dewpoints are expected to mix out into the 60s across the
interior this afternoon as mixing heights increase and
temperatures warm. Dewpoints will likely hold in the 70s closer
to the coast with some dewpoint pooling back into the mid-upper
70s being possible near and behind the sea breeze. Heat indices
should therefore peak in the 100-105 range for most areas with
an area of 105-108 occurring along the US-17 corridor in parts
of Charleston County up into eastern portions of Berkeley County
where some of the more dependable higher resolution guidance
shows the better interaction of the ribbon of higher dewpoints
with the sea breeze with warmer temperatures away from the
beaches. Currently, this falls just sky of local Heat Advisory
criteria (108-112 for 2 hrs or more), but it could be close in a
few spots. Neighborhood probabilities for maximum heat indices
exceeding 108 are running around 10%. NBM dewpoints tend to
exhibit a high bias and were adjusted down to be more consistent
with near term guidance and forecast soundings, especially
inland.

Tonight: Any lingering convection should dissipate early with
the loss of insolation. Deep-layered high pressure centered
offshore will maintain its influence through the night. Lows
will range from the mid 70s inland to the lower 80s at the
beaches and Downtown Charleston.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
The surface pattern will feature high pressure offshore with a
trough of low pressure inland. Aloft, weak flow within subtle
ridging will persist. Thus, the typical summertime sea breeze
pattern will dominate. Low level convergence due to the
proximity of the inland trough could provide some lift for
convection; however, weak subsidence present aloft Tuesday will
limit coverage resulting in isolated to scattered
shower/thunderstorms in the late afternoon/evening. Weak
steering flow and high moisture content (PWATS > 2 inches) could
result in quick bouts of heavy rainfall with little storm
movement; however, this does not look overly concerning as the
overall lifespan of the storms should be on the shorter side.
Coverage looks to increase for Wednesday and Thursday as the
ridge aloft slightly weakens along with subtle signs of DCVA to
the north. High temperatures will jump back in the mid to upper
90s Tuesday with mostly sunny skies forecast. With accompanying
dew points nearing the mid 70s, mainly closer to the coast, heat
indices in a few spots could near Heat Advisory criteria (108
degrees) Tuesday. This will need close watching with forecast
updates. The overnight will be mild with min temperatures in the
mid to upper 70s. Wednesday and Thursday should see highs about
a couple of degrees cooler due to increased convection.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
Not much change in the overall synoptic pattern for the long
term forecast period. The typical summertime sea breeze pattern
will continue with scattered showers and thunderstorms forming
each day especially in the afternoon and early evening when
instability is maximized. Seasonable highs in the low/mid 90s
will rise by a degree or two by the end of the weekend.

&&

.AVIATION /10Z MONDAY THROUGH FRIDAY/...
07/12z TAF Discussion:
KCHS/KJZI/KSAV: VFR for much of the period. Isolated to
scattered showers/tstms are expected to develop this afternoon.
Some of this could get close to the KCHS and KSAV terminals mid-
late afternoon; however, confidence on placement is not high
enough at this time to include a mention of TSRA.

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

&&

.MARINE...
Today: Southwest winds will back to the south this afternoon
with the development of the resultant sea breeze. Winds will
generally average 10-15 kt, but could be closer to 15 kt with
gusts to 20 kt near the land/sea interface and Charleston Harbor
as the sea breeze moves inland. Seas will average 2-4 ft.

Tonight: Winds will veer back to the southwest overnight with
speeds around 10 kt and seas 2-3 ft.

Tuesday through Saturday: Relatively benign conditions are
forecast and as a result no marine concerns expected during the
period. Southwest flow will persist with high pressure to the
east. Wind speeds will be 15 kt or less and seas will average
2-3 ft.

Rip Currents: Lingering swell and enhanced winds with the sea
breeze along the Charleston County coast will support a moderate
risk for rip currents there today. The risk is low elsewhere.

&&

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

&&

$$