074
FXUS62 KCHS 241101
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
601 AM EST Mon Nov 24 2025

...RISK FOR DENSE FOG THIS MORNING..

.SYNOPSIS...
High pressure will prevail early this week, before a cold front
impacts the area mid week. High pressure is expected to return
for Thanksgiving and into the weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
A Dense Fog Advisory has been issued for areas roughly along
and west of I-95 through 10 AM. The advisory goes not include
the coastal zones of Chatham, Bryan and Liberty Counties per
latest satellite trends, but as the fog expands over the next
few hours, it may very well need to be expanded into these zones
along with Coastal Jasper, Beaufort, Coastal Colleton and
possibly Dorchester into the western portions of Charleston
Counties.

The risk for fog will steadily increase through daybreak within
a decoupled boundary layer. Surface observations show a few
observation sites have already dropped below 1SM, but regional
webcams suggest the fog is still fairly shallow and somewhat
patchy. 1000 hPa condensation pressure deficits are only
marginal favorable for dense fog, but given fog is already
starting to form so early in the night with surface dewpoint
depressions approaching zero, the fog has plenty of time to
expand and thicken with time. The risk for significant dense fog
with visibilities 1/4 mile or less looks highest roughly
along/west of the I-95 corridor where the lowest condensation
pressure deficits are progged and 24/00z HREF probabilities for
<1/4 mile are averaging 50-80%. A Special Weather Statement has
been issued to address the going fog situation, but a Dense Fog
Advisory may eventually be needed prior to daybreak. The fog
should mix out by mid-morning.

High pressure will prevail across the region through tonight as
ridging aloft persists. A weak onshore flow will develop later
this afternoon and especially tonight as the center of the
surface high shifts offshore of the Mid-Atlantic coast and a
subtle coastal trough forms just the beaches. A rough shower or
two could approach mainly the lower South Carolina early
Tuesday morning, but most of the overnight hours will feature
dry conditions with marine-based stratocumulus propagating
onshore and a veil of thick cirrostratus aloft spreading in from
the southwest ahead of the storm stream shortwave ejecting out
of the Southern/Central Plains. Highs today will warm into the
lower-mid 70s across the Lowcountry, the mid-upper 70s across
Southeast Georgia with mid-upper 60s at the beaches. Overnight
lows will range from the lower-mid 50s well inland to the lower-
mid 60s at the beaches.

&&

.SHORT TERM /TUESDAY THROUGH THURSDAY/...
Tuesday: High pressure at the surface will shift off the Mid-
Atlantic coast while the upper level ridging originally over the
southeastern states progresses eastward over the adjacent
Atlantic waters. A weak shortwave trough aloft will ripple
across southwesterly flow over the southeastern states. This
weak disturbance could trigger some showers across mainly the
Charleston Tri-County area, with 15-20% PoPs in the forecast.
Temperatures will be above normal again, with mid 70s across
southeastern SC and locations across southeastern GA reaching
into the low 80s. Overnight lows will similarly be above normal,
only dipping into the low 60s.

Wednesday and Thursday: The pattern aloft will shift to a large
trough moving into the eastern CONUS, driving a cold front
across the region Wednesday night into Thursday. Wednesday will
feature highs once again in the upper 70s to low 80s as the
region is situated within the warm sector. Ahead of the front a
line of showers will approach the region Wednesday afternoon,
however the showers will likely be in a diminishing state and is
not expected to be a significant rain-maker. Accumulations
across the region are only forecast to be a few hundredths,
which matches ensemble guidance and NBM probabilities. Areas
west of I-95 have the best chance at seeing rainfall, as the
showers are likely to diminish as they approach the coastline.
Post-FROPA temperatures Wednesday night will dip into the upper
30s inland and 40s along the coastal counties. Thursday will
feature plentiful sunshine, however temperatures are expected to
only top out in the low 60s, with some locations not getting
out of the 50s.

&&

.LONG TERM /THURSDAY NIGHT THROUGH SUNDAY/...
Broad troughing aloft will transition to zonal flow into the
weekend, while high pressure dominates at the surface. This
pattern will yield dry and noticeably cooler weather through the
weekend. Low temperatures Thursday and Friday nights are
forecast to dip below freezing across far inland locations. A
reminder that the local frost/freeze program has ended due to
the widespread freeze earlier this month.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
24/12z TAF Discussion:
KCHS/KJZI/KSAV: Fog will mix out by 13-14z at KCHS/KJZI and
14-15z at KSAV. VFR will then prevail. Conditions could support
a little fog at the terminals early Tuesday morning, especially
at KSAV. Later cycles may need to introduce some fog, but
confidence for impacts this far out is pretty low.

Extended Aviation Outlook: Prevailing VFR.

&&

.MARINE...
Visibility trends are being monitored closely in the Charleston
Harbor where some fog could bleed in from the west/southwest. A
Marine Dense Fog Advisory could be needed for vsbys 1NM or
less, but confidence in dense fog reaching the harbor is not
high enough at this time to hoist the advisory.

Through Tonight: Northeast winds will gradually veer east and
southeast through tonight as high pressure to the north
gradually shifts offshore of the Mid-Atlantic coast. Winds will
average less than 15 kt through the period with seas 4 ft or
less.

Tuesday through Thursday: High pressure will dominate early
this week, with a cold front pushing through the region
Wednesday night. SE winds around 10 knots Tuesday will shift to
the SW on Wednesday, and eventually the NW on Thursday. After
the cold front pushes through winds on Thursday are forecast to
surge to 15 to 20 knots, with some gusts approaching 25 knots.
Small Craft Advisories may eventually be needed for portions of
the marine waters. Seas are forecast to average 2 to 3 ft with
some 4 ft seas in the 20 to 60 nm offshore GA waters.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Dense Fog Advisory until 10 AM EST this morning for GAZ087-088-
     099>101-114>116-118-137-138-140-141.
SC...Dense Fog Advisory until 10 AM EST this morning for SCZ040-042-
     043-047.
MARINE...None.

&&

$$