450
FXUS62 KCHS 011913
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
313 PM EDT Thu Oct 1 2026

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

&&

.KEY MESSAGES...
- 1) Widespread fog expected tonight across interior Southeast
  South Carolina and southeast Georgia. Fog could become dense
  in areas.

- 2) Unsettled weather will return Friday through Monday.

- 3) Cooler temperatures along with breezy to windy conditions
  are likely next week.

- 4) Coastal flooding is likely next week.

&&

.DISCUSSION...
KEY MESSAGE 1: Widespread fog expected tonight across interior
Southeast South Carolina and southeast Georgia. Fog could become
dense in areas.

Broad high pressure will remain over the region resulting in clear
skies and calm winds tonight, creating ideal conditions for fog
development. As temperatures drop and the boundary layer quickly
decouples after sunset, fog is expected to form around
midnight. Models solidly agree and in general there is high
confidence that fog will form across most areas away from the
immediate coast. Additionally, guidance indicates that fog will
likely become dense in some areas (visibilities dropping below
1/4 mile) especially well inland and across the Charleston Tri-
County region, but could expand or spread to the coast. Dense
Fog Advisories could be needed tonight. Similar to previous
mornings`, it could take a couple of hours after sunrise Friday
for the fog to dissipate, around 10 to 11 AM.


KEY MESSAGE 2: Unsettled weather will return Friday through
Monday.

The pattern will get more active as we head into late week, and
especially over the weekend. Upper high pressure will begin to
breakdown into the weekend as our next system moves into the eastern
US. A surge of moisture will move into the area on Saturday as low
pressure develops over the northern Gulf as a backdoor cold front
drops into the Carolinas and stalls around the I-26 corridor. PWATS
are expected to climb above 2 inches by Saturday and peak around
2.25 inches on Sunday which falls in the 98th percentile for this
time of year. This incredibly moist airmass will be the focus for
multiple rounds of rain on Saturday and Sunday with the bulk of the
rain occurring on Sunday afternoon. Rain chances will steadily
increase on Friday afternoon from south to north as the plume of
moisture works northward. Expected isolated to scattered showers
mainly across Georgia on Friday, then gradually expanding northward
in coverage and intensity on Saturday. Given PWATS greater than 2
inches and the focus for low level convergence with the stalled
backdoor front some locally heavy rainfall can be possible,
especially on Sunday. NBM probabilities of >2 inches of rainfall
over 24 hours peak on Sunday around 40% across most of SC including
the Charleston Metro. Rainfall totals of 1 to 3 inches look likely
across most of South Carolina with 2 to 4 inches possible across
Georgia where rain is more likely both Saturday and Sunday. Given
the 98th percentile PWATS and the stalled boundary, localized totals
approaching 5 to 7 inches over the 48 hour period could be possible
and minor flash flooding cannot be ruled out heading into this
weekend. Exact locations and overall focus for heavier rainfall will
likely be ironed out over the next few forecast cycles.

Rainfall will likely come to an end on Monday as the surface cold
front pushes south of the area and strong Cold Air Damming sets up
over the Carolinas. Some overrunning precip will likely continue
across parts of Georgia through the early part of next week as
several weak surface disturbances move along the stalled Wedge
front.


KEY MESSAGE 3: Cooler temperatures along with breezy to windy
conditions are likely next week.

Behind our weekend system, rather strong high pressure will settle
over the Great Lakes region on Monday setting up a classic Cold Air
Damming pattern over the Carolinas. The wedge of cold air will drive
into the region on Monday and persist through the middle part of the
week. Increasing cloud cover and strong north-northeasterly winds
supported by the tightening surface pressure gradient will support
rather mild temperatures to move into the area as highs next week
will likely struggle to reach the upper 60s to low 70s and
considering how model guidance tends to handle CAD scenarios we
would not be surprised if they trend even colder as we get closer.
Along with the cooler temperatures, we are expecting rather gusty
winds early next week. Current guidance supports a greater than 50%
chance across most of the area for wind gusts greater than 30 mph
with potential frequent gusts along the immediate coastline
approaching 40 mph. These conditions would likely warrant a wind
products for most of the area including Lake Moultrie on Tuesday
and potentially Wednesday.


KEY MESSAGE 4: Coastal flooding is likely next week.

Breezy to windy northeast winds induced by strong cold air damming,
combined with already high astronomical high tides, will likely
result in coastal flooding issues early next week. Minor to moderate
flooding is likely, with a possibility of reaching major levels.
Coastal Flood Watches, Warnings and Advisories could be needed.

&&

.AVIATION /18Z THURSDAY THROUGH TUESDAY/...
18Z TAF Discussion: VFR conditions will persist through late evening
before widespread fog is expected to develop tonight around
midnight. The fog will likely become dense (vsbys 1/4 mile or
less) especially well inland and the Tri-County region, but
could expand/spread toward the terminals. There is greater
confidence for dense fog to develop at KCHS/KJZI, hence the
explicit mention in the current TAF. The lowest visibilities are
expected to occur between 08Z and 13Z, and should improve a
couple hours after sunrise Friday (around 14-15Z). VFR
conditions will then return through Friday afternoon.

Extended Aviation Outlook: Flight restrictions are possible with
increasing showers and thunderstorms over the weekend into early
next week. Gusty winds are likely on Tuesday.

&&

.MARINE...
Through Tonight: Quiet weather will continue over the local waters
tonight with light winds and 1-2 ft seas. The main concern will
be fog forming over land late tonight and spreading over the
Intracoastal Waterway and nearshore waters early Friday
morning. Visibilities could fall to 1/2 mile or less, especially
from northern Charleston County south to Hilton Head. Marine
Dense Fog Advisories could be needed before sunlight clears the
fog by late morning (10 to 11 AM).

Friday Through Sunday: Winds and seas will remain well below
Small Craft Advisory thresholds across all marine zones. Winds
will surge a bit each afternoon and evening, but speeds should
mostly top out in the 10-15 knot range and will be strongest
along the land/sea interface. Increasing showers and
thunderstorms are expected over the weekend with Sunday being
the highest rain chances.

Monday and Tuesday: High pressure will wedge south into the
Carolinas and Georgia following the passage of a cold front on
Monday. Marine conditions are expected to deteriorate, with Small
Craft Advisories likely as early as Monday evening. The worst
conditions look to occur on Tuesday when guidance indicates a high
probability for winds to reach gale-force (NBM showing 60-80%
chances for gusts greater than 34 kt, highest in the waters beyond
20 nm). Some gusts could approach 45 knots across the far offshore
waters beyond 20 nm. We will also need to be on the lookout for
hazardous beach conditions, including dangerous rip currents and
high surf.

&&

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

&&

$$

Black/BRS