316
FXUS62 KCHS 062350
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
750 PM EDT Mon Oct 6 2025

.SYNOPSIS...
High pressure will persist into Wednesday. A cold front will
drop south through the area Wednesday night into Thursday with
inland high pressure prevailing into early next week. Low
pressure could develop off the Southeast U.S. coast this
weekend.

&&

.NEAR TERM /THROUGH TUESDAY/...
No precipitation is expected late this evening as winds start
to relax and back from the northeast. A weak mid-level inversion
is forecast to form this evening helping to trap moisture near
the surface. Winds will fully decouple over inland Georgia and
therefore the highest threat of any stratus or fog development
will be across our far western zones/inland Georgia. Expect low
temperatures in the mid 60s inland to lower 70s at area
beaches.

&&

.SHORT TERM /TUESDAY NIGHT THROUGH THURSDAY/...
Tuesday and Wednesday: The region will remain positioned along the
far southwest flanks of Atlantic high pressure centered well
offshore of the Mid-Atlantic states and the far northeastern
periphery of subtropical ridging to the south. This will maintain
moist, onshore flow in place with at least some low-end risk for
spotty measurable rainfall into Wednesday. There may be a slight
increase in rain chances Tuesday morning when some subtle coastal
troughing develops near the beaches and near term pops will reflect
this idea. A cold front will approach Wednesday afternoon, but will
remain well to the west and northwest through the day. Highs both
afternoons will warm into the mid-upper 80s away from the beaches
with lows Wednesday morning dropping into the mid 60s well inland to
the lower-mid 70s at the beaches and immediate coast.

Wednesday Night and Thursday: A potent shortwave will pass by well
to the north Wednesday night into Thursday which help drive a cold
front south into the region. Models are similar in showing a strong
wedge developing over the Southeast U.S. during the day as 1035 hPa
Canadian high pressure builds into New England. A band of scattered
showers and possibly a few tstms will accompany the wedge front as
it drops south. Most of the convection activity looks to remain weak
with model cross sections showing only weak-moderate quasi-
geostrophic forcing noted with a band of passing, mostly channeled
vorticity aloft. Considerably cooler temperatures will occur as the
wedge strengthens. Lows Thursday morning will drop into the 60s. It
will be considerably cooler during the day Thursday with highs only
warming into the lower-mid 70s, except mid-upper 70s south of the I-
16 corridor. Breezy to locally windy conditions will also occur near
the immediate coast and beaches as the pressure gradient induced by
the inland wedge tightens.

&&

.LONG TERM /THURSDAY NIGHT THROUGH MONDAY/...
Much of this period will be dominated by an inland wedge of high
pressure with possible cyclogenesis occurring off the Southeast U.S.
this weekend within the coastal trough offshore. There is a large
number of both the GFS and ECMWF ensemble members showing low
pressure forming off the coast, but the strength and track is still
in question. What is more certain is that the cyclonic flow around
low will help maintain the inland wedge to some degree heading into
Monday even as the parent high over New England weakens and shifts
east into the north Atlantic. Some rain chances were maintained
Friday to account for the developing low offshore with mostly rain-
free conditions prevailing over the weekend into Monday. Below
normal temperatures will prevail for much of the extended period.
Lows could even drop into the lower 50s across parts of the far
interior Monday morning. Breezy to locally windy conditions will
likely occur near the immediate coast and beaches into Saturday due
to the enhanced pressure gradient with the inland wedge and
developing low offshore. Winds will improve late in the weekend as
the pressure gradient begins to relax.

Lake Winds: Winds on Lake Moultrie will become elevated late
Wednesday night into Saturday as a strong, pinched gradient develops
in response to the development of an inland wedge. Winds could get
close to or even exceed Lake Wind Advisory criteria (sustained 20 kt
or frequent gusts to 25 kt) during this time and an advisory may
eventually be needed. Waves could reach as high as 2-3 ft.

&&

.AVIATION /00Z TUESDAY THROUGH SATURDAY/...
00Z TAFs: VCSH should dissipate at KCHS and KJZI by 03Z. Some
of the MOS and ensembles hint at flight restrictions late
tonight through Tuesday morning. Confidence was not high enough
to add this as a TEMPO or prevailing group at any of the TAF
sites. But trends will need to be watched for possible
amendments. Otherwise, VFR should prevail late in the TAF time
period.

Extended Aviation Outlook: Gusty north to northeast winds will impact
the terminals Thursday and Friday, possibly lingering into Saturday
as strong wedge develops inland and low pressure forms offshore.
There are no other high confidence concerns at this time.

&&

.MARINE...
Tonight: High pressure was centered northeast of the coastal
waters with easterly flow across all waters. Small Craft
Advisories are currently in effect for all zones outside of
Charleston Harbor, but seas are borderline for the nearshore
South Carolina waters. The advisory will likely be able to be
dropped for the South Carolina nearshore waters early.

Tuesday and Wednesday: East to northeast winds of 15 kt or less will
prevail through this period as high pressure centered well offshore
of the Mid-Atlantic states. Seas will slowly subside to 3-5 by
Tuesday night with some 6 ft seas persisting into Tuesday morning
with 20 NM and over the Georgia offshore waters Tuesday night where
Small Craft Advisories remain in place. By Wednesday, seas will
subside to 3-4 ft throughout.

Thursday through Saturday: A significant marine event will unfold
later in the weak as a strong wedge of high pressure develops in the
wake of a southward moving cold front. The front is expected to
clear the waters Wednesday night into Thursday with stiff northeast
winds developing Thursday as the wedge strengthens. The resulting
pinched gradient will yield winds 25-30 kt with frequent gusts 35-40
kt from Thursday into Saturday with winds backing more northerly
Saturday as low pressure develops off the coast. Winds in the
Charleston Harbor will be a bit less. Gale Watches and Warnings may
be needed later this week with a Small Craft Advisory in the
Charleston Harbor.

Rip Currents: The risk for rip currents will be highest along
the Georgia beaches Tuesday. A blend of latest rip current MOS
with local rip current calculations support this. A moderate
risk will be in place for all beaches for Wednesday. An enhanced
risk will persist into the weekend due to building surf and
increasing winds associated with the inland wedge.

The risk for high surf will increase Thursday night into possibly as
far out as Saturday. A High Surf Advisory may be needed for some
beaches.

&&

.TIDES/COASTAL FLOODING...
This evening: Minor coastal flooding is possible at Charleston
Harbor with no coastal flooding expected at Fort Pulaski.

Astronomical tides will continue to increase this week due to the
upcoming full moon (Oct 7) and perigee (Oct 8). Additionally, tidal
departure values will only slowly decrease through midweek, before
increasing again Thursday into the weekend as strong NE winds
return. As a result, the threat for mainly minor to moderate coastal
flooding with each high tide cycles continues through mid-week.
Then, late week, the threat for major coastal flooding arrives with
the late morning high tides.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...High Risk for Rip Currents through Tuesday evening for GAZ117-119-
     139-141.
SC...High Risk for Rip Currents until 8 PM EDT this evening for
     SCZ048>051.
     Coastal Flood Advisory until 10 PM EDT this evening for SCZ049-
     050.
MARINE...Small Craft Advisory until 2 AM EDT Tuesday for AMZ350-352.
     Small Craft Advisory until 2 PM EDT Tuesday for AMZ354.
     Small Craft Advisory until 6 AM EDT Wednesday for AMZ374.

&&

$$

NEAR TERM...Haines
SHORT TERM...
LONG TERM...
AVIATION...Haines
MARINE...Haines