988
FXUS62 KCHS 180931
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
531 AM EDT Sat Oct 18 2025

.SYNOPSIS...
High pressure will remain across the region through tonight. A
cold front will move through Sunday night, followed by high
pressure early next week. Another cold front will then arrive
Tuesday night, with high pressure to follow.

&&

.NEAR TERM /THROUGH TONIGHT/...
Through Daybreak: 18/05z temperatures were running several
degrees colder than the 18/01z NBM given the nearly ideal
radiational conditions in place. This trend will continue
through daybreak with low temperatures likely ending up quite a
bit cooler than what the forecast depicts. National "Break the
Glass" criteria is not met, so manual local adjustments to the
gridded forecasts were not made despite observations and trends.
Some areas of interior Southeast South Carolina up into the
Francis Marion National Forest and interior upper Charleston
County may very well see lows bottom out into the upper 40s with
a few isolated instances of mid 40s.

Today and Tonight: Deep-layered high pressure will maintain its
influence on the region through tonight. The center of the
surface high is forecast to shift offshore of the Southeast U.S.
coast later this afternoon and tonight which will yield a weak
southerly flow through the early morning hours Sunday. Some
localized decoupling is likely to develop tonight and there will
likely be some pockets of strong radiational cooling that
occurs, especially in the typically more sheltered areas like
the Francis Marion National Forest. Low-level thickness schemes
support highs in the upper 70s/lower 80s inland with lower-mid
70s at the beaches where the flow will be more heavily
influenced the the cooler Atlantic waters. Overnight lows will
drop into the mid-upper 50s inland with upper 60s/near 70 at the
beaches. A few lower 50s could occur where localized decoupling
develops.

&&

.SHORT TERM /SUNDAY THROUGH TUESDAY/...
A strong cold front will approach Sunday afternoon then cross
the area Sunday night. A fairly contiguous line of showers is
expected to be moving into our western zones shortly after
daybreak. Forcing looks to diminish during the day, and there
could be little precipitation associated with the frontal band
by the time it reaches the coast late Sunday afternoon. The
forecast also shows isolated thunderstorms across inland areas
in the afternoon. Warm advection and pre-frontal compression
should push high temps to around 80 degrees in most spots.

Cool and dry weather then expected Monday and Monday night
before another front approaches late Tuesday. Monday night lows
should be solidly in the 40s away from the coast due to strong
radiational cooling.

&&

.LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/...
Dry high pressure expected through the extended forecast with
no appreciable weather.

&&

.AVIATION /09Z SATURDAY THROUGH WEDNESDAY/...
18/12z TAF Discussion:
KCHS/KJZI/KSAV: VFR through 19/12z.

Extended Aviation Outlook: VFR conditions are expected at all
terminals through Wednesday. However, gusty southerly winds
(15-20 kt) are possible at all terminals Sunday in advance of a
cold front.

&&

.MARINE...
Through Tonight: A southerly wind flow will strengthen today
and especially tonight as high pressure shifts offshore and a
cold front approaches from the west. Speeds will average less
than 10 kt today, although there could be some localized
enhancements near the land/sea breeze interface this afternoon,
then increase to 10-15 kt tonight. Seas will range from 2-3 ft
nearshore waters and 3-5 ft over the Georgia offshore waters.

Sunday through Wednesday: Marginal Small Craft Advisory
conditions, mainly due to 25 kt gusts, possible Sunday night
into Monday morning following a strong cold front. Another brief
surge will follow a secondary cold front Tuesday night, but
winds/seas look to remain below advisory thresholds.

Rip Currents: Another period of enhanced rip current risk is
possible for all beaches Sunday due to increasing swell and
gusty onshore flow ahead of an approaching cold front.

&&

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

&&

$$