783
FXUS62 KCHS 031801
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
201 PM EDT Thu Jul 3 2025

.SYNOPSIS...
A stalled front will linger in the vicinity through the
weekend. An area of low pressure could develop along the front
off the Southeast coast late this week.

&&

.NEAR TERM /THROUGH TONIGHT/...
This afternoon and evening: Surface analysis shows a very weak
and subtle front/boundary situated just inland and stretches
from south GA up through the SC Midlands and into central NC.
The main gradient across the area is precipitable water. Values
across the SC Midlands and central GA are down into the 1-1.25"
range with 2-2.25" along the coast of the forecast area. The
area is also within baggy troughing aloft with the main spoke of
vorticity along the coast and expected to shift offshore
through the afternoon. So, with this setup the best environment
for convection appears to be along the immediate coast of the
forecast area. MLCAPE values are expected to peak in the
2,000-2,500 J/kg range across the area with a tight DCAPE
gradient across the area. Further inland, coincident with the
lower precipitable water airmass, DCAPE values are 1,000 J/kg or
higher while areas along the coast values are generally 800
J/kg or lower. So, while less convective coverage is expected
inland, the better severe environment exists there. But we could
still see an isolated strong to marginally severe storm along
the coast, especially where boundary interactions occur. Along
the coast where the better coverage is expected, the locally
heavy rain threat is higher. Storms will be relatively slow
moving and with precipitable water values at or above 2", rain
rates could be intense at times and produce a quick 1-2" of
rainfall in some localized areas. Convection movement and
coverage will largely be determined by boundary interactions
into the mid to late evening hours, but should generally be
diminishing by the late evening.

Overnight: While land areas should mostly be dry, there will
still be subtle residual boundaries floating around that could
provide sufficient trigger to kick off an isolated shower or
thunderstorm. But overall, the focus for overnight showers and
storms should shift offshore. While there is potential for
pockets of shallow ground fog overnight, the threat for
significant fog is low. Lows are forecast to be in the low to
mid 70s.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
Independence Day: A stalled front is expected to be located off
the SC/GA coast on Friday, extending down across the Florida
peninsula. Diurnal showers and thunderstorms are expected to
develop, but coverage should be less than today, with PoPs
largely in the 20-30% range. The threat for organized severe
weather is low, but a stronger storm or two is possible. High
temperatures are forecast to be in the low 90s away from the
immediate coast/beaches, with heat indices topping out in the
97-103 F range. Convection should wane with sunset, although
some shower activity could develop over the waters and drift
towards and possibly onshore overnight. Lows will be near
normal.

Weekend: Focus for the weekend will be on the potential for low
pressure to develop off the Southeast coast. NHC currently
indicates a medium/60% chance of formation. The anticipation is
that this system, should it develop, will remain relatively
weak. Regardless of tropical delineation, there is potential for
locally heavy rain and gusty winds, especially along the coast.
Current NBM probabilities indicate 40-50% chance for rainfall
greater than 1 inch Friday through Sunday near the coast (l0-30%
inland); and around 20% for greater than 2 inches primarily
along the SC coast. While there does not appear to be a
widespread flooding concern, minor flooding especially in low-
lying and poor drainage areas is possible. For winds, reasonable
worst case scenario shows the threat of sustained winds of
tropical storm force confined to the beaches and coastal waters.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
An area of low pressure should pull away from the region early
next week, with the surface pattern to then feature high
pressure offshore with a trough of low pressure inland through
midweek. Rain chances will be typical of summertime, 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 THURSDAY THROUGH TUESDAY/...
The 18z TAF period starts with showers and thunderstorms near
KCHS, KJZI, and KSAV. The primary time period for thunderstorm
impacts will be from 18-21z, as storms should then dissipate and
move away from the terminals. For the late evening and
overnight hours the expectation is for dry conditions, but you
can never completely rule out an isolated shower or thunderstorm
at any time given how moist the environment is with a boundary
near by. Fog potential is low overnight as well, though there
could some shallow ground fog nearby. Looking ahead to Friday,
the best chance for isolated to scattered thunderstorms should
come just beyond the end of the 18z TAF period.

Extended Aviation Outlook: Brief flight restrictions are
possible in afternoon showers and thunderstorms on Friday. There
will be a greater chance for flight restrictions in
precipitation and low clouds over the weekend, especially if low
pressure develops off the Southeast coast.

&&

.MARINE...
Through tonight: Overall, pretty benign conditions expected
across the local waters. Wind speeds should mostly be no more
than 10 knots with seas 2-3 feet on average. Thunderstorms along
the coast this evening could produce gusty winds and frequent
lightning. Then overnight, at least isolated to scattered
thunderstorms are expected across the coastal waters.

Friday through Tuesday: Main focus for late week into the
weekend is the potential development of low pressure off the
Southeast coast, which NHC currently has a 60% chance of
developing. Regardless, this system should remain relatively
weak. Current forecast indicates Small Craft Advisory conditions
Saturday into Saturday night, but given uncertainty there could
be notable changes in future forecast updates. Any low that
forms should pull away from the region early next week.
Southerly flow should return with speeds 15 knots or less and
seas 2-3 feet.

Rip Currents: Gusty winds and increasing swell energy, along
with considerations of the July 4 holiday, will lead to an
enhanced risk of rip currents at area beaches late week into the
weekend. A Moderate Risk is currently forecast for both Friday
and Saturday. A High Risk could be needed, particularly for the
Charleston county, on Saturday especially if low pressure
develops off the coast.

&&

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

&&

$$

NEAR TERM...BSH
SHORT TERM...ETM
LONG TERM...ETM
AVIATION...BSH/ETM
MARINE...BSH/ETM