614
FXUS62 KCHS 061800
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
200 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 TONIGHT/...
Today: A complex flow pattern was analyzed at 250 and 500 mb this
morning with multiple pieces of leftover PV underneath a mid-level
ridge off the east coast of the United States. One piece of the
aforementioned PV was analyzed on water vapor this morning over
South Carolina and is forecast to shear out through the afternoon.
At the surface, high pressure was analyzed just east off of the Mid-
Atlantic coast with a coastal trough on the southern flank of the
ridge or near the South Carolina/ Georgia coast. Ahead of the
coastal trough, showers have developed and are moving onshore. The
coastal trough has already started to push onshore this afternoon
and will eventually wash out late this afternoon/ early evening. As
overcast skies become broken to scattered, temperatures will quickly
warm into the lower to mid 80s this afternoon. KCHS is already 83F
as of 110 PM this afternoon.

Tonight: No precipitation is expected 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 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 /18Z MONDAY THROUGH SATURDAY/...
Today: A mix of VFR and MVFR conditions at the terminals this
afternoon as showers slowly move inland. The precipitation
across the terminals is thanks to a weak coastal trough that is
forecast to move inland this afternoon and slowly dissipate. All
terminals will go VFR this afternoon with winds out of the
northeast.

Tonight: VFR conditions initially with winds becoming light and out
of the north. A weak mid-level inversion is also forecast to form
helping to trap moisture in the low levels of the atmosphere. Some
guidance is showing either fog or stratus trying to develop
overnight into Tuesday morning. The best chances appear inland
of the terminals (where winds will be lighter), but have started
hinting at the potential for stratus and fog at KCHS and KSAV.

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...
Today and Tonight: High pressure was centered northeast of the
coastal waters this afternoon with easterly flow across all
waters. A weak coastal trough from this morning has started to
move inland with skies slowly clearing over the waters with seas
5 to 7 ft. 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 from 6 PM to 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/