109
FXUS62 KCHS 032207
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
507 PM EST Wed Dec 3 2025

.SYNOPSIS...
High pressure will prevail across the region before a frontal
system impacts the area Friday into the weekend. High pressure
will then return next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...
Sfc high pressure will slowly build across the region under a
zonal flow aloft, favoring dry and cool weather conditions
through the night. Latest guidance suggests cloud cover to erode
during the overnight period, supporting decoupling winds as
some form of radiational cooling takes place. Given recent
rainfall, the combination of wet grounds and a light/calm wind
could support some patchy fog late night. However, high clouds
(cirrus) sourced from an upstream system across the southern
United States could limit more substantial fog coverage and/or
result in mainly shallow ground fog locally. Overnight lows will
be a bit colder than the previous night should clouds erode
substantially, with some locations reaching the freezing mark
well inland. Lows should generally range in the upper 30s/lower
40s near the coast.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH SATURDAY NIGHT/...
The surface high pressure dissipates throughout the day, with
scattered shortwaves in the mid-levels beginning to move across
the area by the afternoon hours. Dry air in the low-levels
should keep majority of the rain from reaching the ground in the
early afternoon, but top-down saturation will eventually
saturate the lower-levels especially across southeast Georgia by
the late afternoon hours. Given the mostly cloudy skies and
chances for rain, expect another below normal temperatures to
continue, with highs in the upper 50s to lower 60s.

Overnight into Friday, an inverted trough builds into the
region, and with isentropic lift in the mid-levels expect
rainfall chances to be increasing both probabilistically and in
spatial extent. This marks the beginning of a rather prolonged
period where rain showers are expected, with global ensembles
all indicating a 40-80+% chance for at least light rainfall
during each 6 hour period lasting into Saturday night. With
precipitable water values in the 1.25-1.5" range (at or above
the 90th percentile of climatology) and up to 500 J/kg of
MUCAPE, ensembles suggest at most 0.5-1.0 inch of rain from
2-7pm Friday, with generally 0.25-0.5 inches during the 6 hour
windows Friday morning and evening.

Heading overnight into Saturday, scattered shortwaves continue
to push across the area resulting in additional chances for
light rainfall, with the aforementioned inverted trough
converting into more of a stationary front draped from the
Florida panhandle into our nearshore waters. As additional
scattered shortwaves move across the area, the region also falls
into the right entrance region of the upper level jet, and
combined with the front nearby we will see another round of rain
showers Saturday continuing into the overnight hours. 48 hour
rainfall probabilities ending Saturday night are lowest along
the coast, where a 40-60% chance for an inch exists (10- 20% for
2 inches), and highest inland where a 70-90% chance for an inch
exists (50-60% for 2 inches). High temperatures on both Friday
and Saturday expected to remain in the lower 50s inland to mid
50s to mid 60s along the coast, with overnight lows in the lower
40s to lower 50s.

&&

.LONG TERM /SUNDAY THROUGH WEDNESDAY/...
The mid-level trough that has been sitting over the central
CONUS finally begins to head eastwards, but with the shortwaves
continuing to stream across the region chances for light
rainfall continue into Sunday. A cold front push through into
Monday followed by surface high pressure, which will bring an
end to the chances for rainfall, though the below normal
temperatures continue. The ECMWF is most aggressive with ending
precip as described above, though the GEFS and GEPS are less
convinced and think the precip could linger into the evening
hours. Monday night into Tuesday has high probabilities (80%)
for reaching temperatures below freezing for areas inland,
dropping to 30-40% along the coast, with a similar set up for
Tuesday night into Wednesday.

&&

.AVIATION /22Z WEDNESDAY THROUGH MONDAY/...
04/00Z TAF Discussion:
KCHS/KJZI/KSAV: VFR will prevail at all three sites through
much of the 00z TAF period. Clouds have been persistent at KCHS
and KJZI today and will likely linger a bit longer through the
evening hours. There are some data that support a brief period
of MVFR cigs just before clearing occurs. This possibility was
handled with a TEMPO group from 04-07z at both sites.

Extended Aviation Outlook: VFR conditions expected for Thursday.
There are moderate probabilities (30-50%) for flight restrictions
late Thursday into Friday morning, due to low ceilings from
scattered showers. Probabilities for MVFR cigs increase into the 60-
90% range (30-60% for IFR cigs) on Friday as more widespread showers
move in, with near 50% chance for MVFR vsbys as well. MVFR (or
worse) conditions expected to remain possible throughout the day
on Saturday, with conditions expected to begin to improve on
Sunday but especially on Monday.

&&

.MARINE...
Tonight: There are no concerns across local marine zones. A
weak front will stall nearby while high pressure gradually
spreads across the region overnight. This will place a weak
pressure gradient across local waters with northwest winds
around 10-15 kt during the day slightly weakening overnight.
Seas will remain between 2-3 ft.

Thursday to Sunday: No marine hazards expected. For Thursday,
expect 2-3 ft seas with north winds becoming northwest at 10 to
15 knots. Winds turn northeasterly overnight into Friday as
scattered showers begin to overspread the region, but will
become variable as a coastal low moves northeast, becoming
northerly again on Saturday with seas expected to remain in the
2-4 ft range. A cold front crosses the waters on Sunday, keeping
winds out of the north at 10 to 15 knots, with rainfall
expected to end overnight into Monday.

&&

.TIDES/COASTAL FLOODING...
Astronomical tides will continue to rise with the morning high
tide cycles through Friday and remain elevated through the
weekend. Coastal Flood Advisories will likely be needed for
morning high tide cycles, primarily at Charleston Harbor
(Charleston and Coastal Colleton counties) through Saturday
morning.

Friday, astronomical high tides peak (6.8 ft MLLW at Charleston
Harbor and 8.86 ft MLLW at Fort Pulaski) and this is when winds
are forecast to turn from the northeast. Overall, this type of
setup can over perform given the building anomalies from the
northeast winds. The forecast remains largely unchanged, with
moderate coastal flooding at Charleston Harbor and minor coastal
flooding at Fort Pulaski.

&&

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

&&

$$