947
FXUS62 KCHS 181822
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
222 PM EDT Fri Sep 18 2026

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

&&

.KEY MESSAGES...
- 1) Rain chances will then gradually increase this weekend and
  especially by early next week.

&&

.DISCUSSION...
KEY MESSAGE 1: Rain chances will then gradually increase this
weekend and especially by early next week.

This afternoon and tonight: Aloft, the forecast area will
continue to sit between prominent ridging and an anticyclone to
the west and an upper low across the FL peninsula. This will
drive northeast flow aloft and also support a similar storm
motion. At the surface, a surface trough positioned to the north
will be the primary feature of interest. For the afternoon,
there is virtually no support for development across the area
due to the lack of any real initiation features. A few showers
could push through from upstream within the deep northeast flow,
but otherwise we should remain convection-free through sunset.
Of more interest is the potential for upstream activity to
develop along the aforementioned surface trough and make a run
for the forecast area late this evening or in the early morning
hours. The good news is that we will be long past peak heating
and the environment this upstream convection will be moving into
will not be particularly supportive of maintenance or continued
development. So, it seems reasonable that the hi-res models and
the 18/12z HREF show minimal coverage with no support for
thunder and little (if any) rainfall.

Saturday and Sunday: Aloft, a mid-upper lvl low will pass south
of the local area, shifting across the Florida Peninsula and to
the Northeast Gulf. At the sfc, a weak front will approach from
the north this weekend, potentially reaching the local area
late Saturday into early Sunday before stalling/dissipating
early week. The setup will favor deep moisture transport across
the Southeast United States within a southerly flow with PWATs
approaching 2.25 inches locally, and likely support unsettled
weather conditions in the form of showers/thunderstorms given
sufficient forcing and abundant sfc heating (highs in low-mid
90s Saturday, then upper 80s/lower 90s Sunday). Given a moisture
rich airmass, rounds of afternoon/evening convection and a
front nearby, there could be a low-end threat for locally heavy
rainfall and minor flooding issues. However, minimal shear and
modest instability will limit the severe weather threat.

Monday through mid-week: The previously mentioned mid-upper low
feature is anticipated to drift north across the Southeast
United States early week, eventually phasing with a longwave
trough passing across the Midwest and Northeast United States
through mid-week. The passing low along with the arrival of a
stronger cold front from the north should lead to a slightly
more active weather period in regards to shower and thunderstorm
coverage, and could lead to a greater risk for a few strong
and/or marginally severe thunderstorms during peak heating hours
heading into the middle of the week. Additionally, moisture
levels remain high (PWATS 2+ inches), suggesting at least some
minor flooding concerns while the front is nearby.

&&

.AVIATION /18Z FRIDAY THROUGH WEDNESDAY/...
The 18z TAF period begins with VFR conditions at KCHS, KJZI,
and KSAV. A few showers could pass by KCHS and KJZI early this
afternoon, but otherwise conditions should remain free of
showers and thunderstorms through sunset. Late this evening and
into the early morning hours, we could see isolated to scattered
showers move into the vicinity of the terminals, but no
significant impacts are expected. Winds will turn onshore out of
the south or southeast in the next couple of hours, then will
be light and variable overnight.

Extended Aviation Outlook: Shower/thunderstorm chances are
expected to increase late weekend and into early next week with
the approach of multiple fronts and increasing moisture levels.
Periodic flight restrictions are possible daily at CHS/JZI/SAV
terminals as a result through early next week.

&&

.MARINE...
Through tonight: 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
start off 2-3 feet, then diminish to just be 2 feet late.

Saturday through Wednesday: There are no marine concerns this
weekend into early next week as winds/seas are expected to
remain well below Small Craft Advisory levels. In general, winds
will remain around 10 kt or less with seas in the 2-3 ft range.
However, a cold front is anticipated to reach the area by the
middle of next week, which should produce an uptick in winds
(15-20 kt) and build seas (3-5 ft). Trends will need to be
monitored for potential Small Craft Advisory level conditions
around mid week. Additionally, shower/thunderstorm coverage is
expected to increase next week ahead/along the approaching
front.

&&

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

&&

$$

BSH/DPB