468
FXUS62 KCHS 061127
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
727 AM EDT Mon Oct 6 2025

.SYNOPSIS...
High pressure ridges in from the north through Wednesday. A
strong backdoor cold front will cross the area later Wednesday
into Thursday, with inland ridging persisting into the weekend
as low pressure potentially passes off the Southeast coast.

&&

.NEAR TERM /THROUGH TONIGHT/...
Today: Aloft, mid-upper lvl ridging will persist across the
Mid-Atlantic states while h5 vort energy shifts north across
the Deep South and potentially into the Southeast along its
southwestern edge. At the sfc, an inverted trough should persist
off the SC/GA coast for much of the day along the southern
periphery of high pressure extending from the western Atlantic
into the Mid-Atlantic states, and appearing to hold just inland
of the local area. Much like the previous morning, coastal
showers will be driven onshore within an easterly wind,
producing light to moderate rains across the South Carolina and
Georgia coastal corridor, before becoming more focused across
Southeast Georgia late morning into early afternoon as h5 vort
energy traverses aloft. Weak isentropic lift and PWATS in the
1.7 to 1.9 inch range should support few to scattered showers,
even well inland as sfc temps warm into the low- mid 80s early
afternoon. Although the progression of precip activity is
somewhat quick and less supportive for flooding/flash flooding,
sufficient instability remains along the beaches to support a
thunderstorm capable of a brief downpour late morning/early
afternoon (south of Beaufort, SC into Southeast Georgia).
Rainfall accumulations around 1/2 inch are possible in some
spots, although could be upwards to an inch if a thunderstorm is
able to develop and shift onshore across coastal Southeast
Georgia. Breezy easterly should also develop along the coastal
corridor early afternoon, generally gusting to around 20 mph.

Tonight: The bulk of guidance indicates deepest moisture shifting
inland and h5 vort energy departing to the north by nightfall,
suggesting any lingering showers to wane/dissipate rather quickly by
sunset. We could see additional showers develop across coastal
waters overnight as an inverted trough lingers, and some of this
activity has the potential of shifting onshore late night/early
morning to a lessor extent than previous nights with signs of the
inverted trough attempting to weaken and/or shift onshore late. East-
northeast winds should become rather light after midnight. Low temps
should range in the mid 60s inland to low 70s closer to the
coast.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
Broad upper ridging extending across the South persists Tuesday into
Wednesday. Then, later Wednesday, H5 heights begin to fall as a
southern stream shortwave digs toward the Southeast. At the surface,
Tuesday and Wednesday remain mostly dry as the surface ridge axis
moves overhead. By Wednesday night, a backdoor cold front associated
with strong high pressure building over the Northeast approaches the
area, with enough moisture in place to justify chance POPs
overspreading the area from north to south Wednesday night into
Thursday. QPF will be limited, and periods of light rainfall may end
up being mixed with drizzle as the shallow ridging undercuts the
ample low level moisture already in place.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
The forecast for Friday into the weekend is beginning to come into
better focus as strong inland ridging persists, with troughing
and/or a closed low developing off the Southeast coast. NE winds are
likely to persist through at least Saturday, with wind strength
being largely predicated on the characteristics of the offshore low.
A strong low passing nearby off the coast could bring strong winds,
and there is ~10% chance or less that advisory level winds occur
along the beaches.  Additionally, there will likely be extensive
precipitation over the Atlantic, but the amount of that precip that
makes it back to land is uncertain given the very dry air inland,
and a mainly dry weekend forecast is in place for most of the area
at this time.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
TEMPO MVFR conditions are possible between 12-14Z at CHS/JZI
and TEMPO MVFR/IFR conditions are possible between 12-14Z at SAV
for showers shifting onshore early morning. VCSH remain at all
terminals into late morning and possibly into early afternoon at
SAV, which could result in additional brief periods of flight
restrictions, but confidence is too low to include in the 12Z
TAF issuance. Another breezy day is anticipated with easterly
winds gusting upwards to 15-20 kt at all terminals. VFR conditions
are then expected to prevail this afternoon, then persist
through 12Z Tuesday.

Extended Aviation Forecast: VFR conditions expected to prevail. Be
alert to the potential for Gusty NE to develop behind a backdoor
cold front Thursday.

&&

.MARINE...
High pressure will remain centered north of the region while an
inverted trough remains offshore, leading to an easterly flow across
local waters along with gusty showers (potentially thunderstorms). A
somewhat enhanced pressure gradient between these features should
start to weaken during the day, but still supports wind gusts
upwards to the 15-20 kt range. Seas will be the main concern,
generally ranging between 4-6 ft nearshore and 6-8 ft across outer
Georgia waters. Small Craft Advisories will therefore remain in
place for all local waters outside the Charleston Harbor today and
tonight, but conditions will be improving overnight and it is
anticipated that a portion of nearshore waters will see conditions
drop below Small Craft Advisory levels after midnight.

Seas will finally fall below hazardous levels Tuesday and
Wednesday, allowing Small Craft Advisories to come down. Then, a
backdoor cold front will cross the waters late Wednesday into
Thursday morning, bringing strong NE winds and a return of
hazardous conditions. Gale force winds are possible late in the
week and into the weekend, depending on the development of low
pressure that will pass well offshore.

Rip Currents: A high risk of rip currents will continue through
today in primarily medium period E to NE swells. The risk for
enhanced rips will continue into Tuesday as well.

&&

.TIDES/COASTAL FLOODING...
This Morning: Latest tide observations and guidance support
minor/moderate coastal flooding for Charleston and Coastal Colleton
Counties, near 7.5 ft MLLW with the morning high tide around 7:35 AM
at Charleston Harbor. A Coastal Flood Advisory is now in effect from
5 AM to 10 AM this morning. At Fort Pulaski, recent observations
suggest tidal departures not as large as the previous high tide
cycle, which could limit the potential for coastal flooding along
Beaufort, SC and south across Southeast Georgia coastal communities.
Tide levels could fall just short of minor coastal flooding levels.
Trends will need to be monitored during the next few hours to
determine if the Coastal Flood Advisory needs to be extended south
along the coast.

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...Coastal Flood Advisory until 10 AM EDT this morning for GAZ117-
     119-139-141.
     High Risk for Rip Currents through this evening for GAZ117-119-139-
     141.
SC...Coastal Flood Advisory until 10 AM EDT this morning for
     SCZ048>051.
     High Risk for Rip Currents through this evening for SCZ048>051.
MARINE...Small Craft Advisory until 2 AM EDT Tuesday for AMZ350-352.
     Small Craft Advisory until 11 AM EDT Tuesday for AMZ354.
     Small Craft Advisory until 6 AM EDT Wednesday for AMZ374.

&&

$$

NEAR TERM...DPB
SHORT TERM...CEB
LONG TERM...CEB
AVIATION...CEB/DPB
MARINE...CEB/DPB