171
FXUS62 KCHS 191102
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
702 AM EDT Sat Sep 19 2026

.WHAT HAS CHANGED...
Aviation section has been updated to reflect the 12z Aviation
forecast.

&&

.KEY MESSAGES...
- 1) Rain chances will then gradually increase this weekend and
  especially by early next week. Cooler temperatures return by
  the end of the week.

&&

.DISCUSSION...
KEY MESSAGE 1: Rain chances will then gradually increase this
weekend and especially by early next week. Cooler temperatures
return by the end of the week.

Saturday and Sunday: Increasingly unsettled weather will begin
to setup this weekend as an upper level low slowly drifts across
Florida and into the northern Gulf. At the surface a weak
backdoor front will slip into the area from the north late
Saturday evening into the day on Sunday. Moisture will increase
throughout the weekend as we move to the eastern side of the
upper low and the surface front sags into the area. PWATS
should approach the 2 inch range by Saturday afternoon and
increased chances for showers and thunderstorms will be expected
Saturday and Sunday. The best chances this afternoon look to be
mainly around the Tri-county area where the influences of the
backdoor front will be and along a slow moving seabreeze this
afternoon. By Sunday, rain chances look to be more confined to
the seabreeze. Given PWATS near 2 inches, a localized heavy
rainfall threat cannot be ruled out; however, rather poor
instability and no real focus for continued redevelopment would
likely not support a more widespread heavy rain issue. Poor
instability and little to no deep layer flow will also likely
limit the severe potential.

Monday Onward: An upper-level low over the Florida Peninsula will
weaken as it gets swept northeast by an approaching longwave trough.
The combination of the upper low and an incoming surface cold front
will yield an increase in shower and thunderstorm coverage through
midweek. The highest storm coverage, along with a localized threat
for heavy rainfall and minor flooding (given PWATs 2+ inches), will
align with the arrival of the front Tuesday into Wednesday. During
peak afternoon heating, a few strong thunderstorms will also be
possible, but the overall severe threat looks to be limited.

A noticeable cool-down will take hold on Thursday behind the passage
of the cold front as high pressure wedges south, ushering in cold
air advection. Cooler, drier conditions will persist through the end
of the week with highs currently forecast to top out in the upper
70s to lower 80s across southeast South Carolina and the mid 80s in
southeast Georgia. Overnight low temperatures will fall into the
lower 60s away from the immediate coast.

&&

.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
19/12z TAFs:VFR conditions should prevail throughout the
forecast with winds becoming light and easterly during the
afternoon. A few showers could be possible around CHS/JZI during
the late afternoon before clearing during the early evening.
MVFR ceilings should spread south after midnight as a weak front
slowly moves through the area.

Extended Aviation Outlook: Shower/thunderstorm chances are expected
to peak Tuesday into Wednesday with the approach of a cold
front. Periodic flight restrictions are possible.

&&

.MARINE...
Today: Very quiet conditions will prevail across the local
waters. Winds will be strongest this afternoon and through the
evening along the land/sea interface with the sea breeze, though
winds should peak in the 10-15 knot range. Then overnight,
winds will diminish to be 5 knots or less. Seas will average 1-2
ft, except 2-3 ft early for the Georgia offshore leg.

Sunday through Thursday: There are no marine concerns through early
next week as winds/seas are expected to remain well below Small
Craft Advisory levels. However, a cold front is anticipated to reach
the area by the middle of next week, which is expected to produce an
uptick in winds with gusts nearing 25 kt, along with building seas
(3-6 ft). Trends will need to be monitored for potential Small Craft
Advisory level conditions. Additionally, shower/thunderstorm
coverage is expected to increase during the middle of next week
ahead/along the approaching front.

&&

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

&&

$$

Black/BRS