290
FXUS62 KCHS 211111
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
711 AM EDT Mon Sep 21 2026

.WHAT HAS CHANGED...
All sections have been updated

&&

.KEY MESSAGES...
- 1) Daily thunderstorms are expected across southeast Georgia
  and southeast South Carolina today with rain chances
  increasing Tuesday and Wednesday.

- 2) A mid-week cold front will bring a threat of strong
  thunderstorms Wednesday afternoon, followed by cooler weather
  and gusty winds.

&&

.DISCUSSION...
KEY MESSAGE 1: Daily thunderstorms are expected across
southeast Georgia and southeast South Carolina this weekend and
into early next week. An increase in rain chances is expected by
the middle of next week, with cooler temperatures thereafter.

Today: Very little change in the pattern from the past few days
with an upper level low parked over the Florida Peninsula.
Moisture continues to stream are the upper low and into the area
as PWATS continue to hover around 2 inches across the area.
Given rather weak forcing aloft storms will likely be more
isolated in nature focused along the slowly advancing seabreeze.

Tuesday: The aforementioned upper low across the Florida
Peninsula is anticipated to drift north-northeast across the
Southeast United States, eventually phasing with a longwave
trough shifting across the Mid-Atlantic and Northeast mid-week.
Forcing associated with this feature will support increased
shower and thunderstorm activity, along with the potential for a
few strong or marginally severe thunderstorms Tuesday. The
presence of deep moisture (PWATS 2+ inches) could also produce a
threat for localized heavy rainfall and minor flooding.

KEY MESSAGE 2: A mid-week cold front will bring a threat of strong
thunderstorms Wednesday afternoon, followed by cooler weather and
gusty winds.

A cold front is progged to push south across the forecast area as an
upper trough digs into the Southeast. Model guidance has slowed the
cold front`s progression across the area to late Tuesday night
through Wednesday evening. While the overnight/early morning arrival
will limit the severe weather threat Wednesday morning, especially
across southeast South Carolina, afternoon heating south of the
front will destabilize the warm and moist airmass out ahead. This
creates a risk for strong to severe thunderstorms Wednesday
afternoon, primarily across southeast Georgia.

Following the front, an inland wedge pattern will set up, and cool
and dry conditions will persist through the remainder of the week.
High temperatures will top out in the upper 70s to lower 80s in
southeast South Carolina and the low to mid 80s in southeast
Georgia, roughly a few degrees below normal for late September.
Gusty post-frontal winds of 25 to 30 mph are also likely on
Thursday.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Mostly VFR conditions prevail across the area. A few scattered
showers and storms are occurring across coastal GA and SC which
may result in temporary reductions to MVFR vsbys and ceilings.
Overall shower and thunderstorm chances look very low for Monday
afternoon and evening. Winds will remain light out of the
northeast becoming easterly during the afternoon.

Extended Aviation Outlook: The main potential for flight
restrictions will come from afternoon and evening showers and
thunderstorms each day. The best chance of showers and thunderstorms
is expected to come Tuesday into Wednesday as a cold front shifts
across the area. Post-frontal gusty winds will likely impact the
terminals Thursday.

&&

.MARINE...
Today through Tonight: A decaying surface high pressure ahead
of a slowly approaching cold front will continue the benign
marine weather conditions across our local waters. Periodic
showers and thunderstorms during this time may be capable of
gusty winds and frequent lightning.

Tuesday through Saturday: Quiet marine conditions are expected
Tuesday before a cold front pushes through Wednesday. In the wake of
the front, an inland wedge pattern coupled with a deepening surface
low off the Mid-Atlantic coast will drive a strong surge in
northeasterly winds. Conditions will deteriorate Wednesday evening
with wind gusts peaking near gale force Thursday evening. Small
Craft Advisories will likely be needed, and Gale Watches/Warnings
could be required. In addition, seas will build alongside the surge,
peaking between 5-9 ft Thursday night. Conditions will begin to
improve Saturday as the pressure gradient relaxes.

Coastal Flooding: We will need to keep an eye on the potential
for minor coastal flooding Thursday as strong northeasterly
winds combine with astronomical high tide. Current forecast for
Charleston Harbor is 6.9 Ft MLLW.

&&

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

&&

$$

Black/BRS