852
FXUS62 KCHS 122258
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
658 PM EDT Sat Jul 12 2025

.SYNOPSIS...
Weak high pressure will continue to build across the region
into early next week. By mid-week, a surface front might sag
into the region increasing storm activity.

&&

.NEAR TERM /THROUGH SUNDAY/...
Early this evening, a large arcing outflow boundary was
spreading across the forecast area. Scattered showers and
thunderstorms were develop just behind the boundary, with most
of the coverage expected over SE GA through the rest of the
evening. The forecast update will align hourly temperatures with
the pool of rain-cooled temperatures in the mid to upper 70s.
Ongoing convection will likely cool temperatures quickly into
the 70s by mid-evening.

Tonight: Showers and thunderstorms are forecast to diminish with
nightfall, when the best chances for precipitation shifts
offshore. Overnight temperatures will be near normal in the 70s.

&&

.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
A weak upper-lvl ridge will briefly build across the Gulf Coast this
weekend. Simultaneously, a broad ridge will remain off the East
Coast as rich moisture continues to advect into the region with PWAT
values ~2.0 inches through early next week. This will be more than
enough moisture to spark up some showers and thunderstorms each
afternoon as the sea breeze pushes inland. Expect temperatures to be
in the mid to upper 90s on Sunday and Monday, with upper 80s to low
90s on Tuesday. Heat index values look to be in the 100 to the 107
degree range, specifically on Sunday and Monday in the afternoon
hours. As of right now, these values remain under Heat Advisory
Criteria (108F), however we will continue to be monitor these values
over the next couple days. With these temperatures in place and
dewpoints in the the low to mid 70s, moderate instability should
develop and it`s possible to see strong to severe thunderstorms each
afternoon. Overnight lows will remain mild and only dip into the low
to mid 70s (with warmer temperatures closer to the beaches).

&&

.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
This current pattern will be slow to change as this weak upper-lvl
ridge eventually begins to break down in the middle part of next
week. A weak front could settle nearby with storm activity gradually
increasing by the end of the week. In addition to the front, there
is some indication of a weak surface low developing over the Florida
Panhandle sometime next week and allow for an enhanced region of
moisture to advect across the Southeast. With this setup, heavy
rainfall could be an issue, however models remain all over the place
with the rainfall amounts that it`s difficult to pinpoint exact
locations this far out in the forecast. Temperatures will remain
near normal for this time of the year.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Prior to the 18Z TAFs, a large arcing outflow boundary was
spreading across the forecast area. Along and behind the
boundary, scattered thunderstorms were developing, especially
near KSAV. The KSAV TAF will initialize with a mention of
showers with vicinity thunderstorms, lingering until 2Z. KJZI
and KCHS may see some VCSH through mid-evening, then the rest of
the evening should be dry and VFR. It appears that the sea
breeze convection will be near or over the terminals between
18-22Z, highlighted with TEMPOs.

Extended Aviation Outlook: VFR will mainly prevail throughout the
period, however brief flight restrictions are possible within
showers and thunderstorms that develop in the afternoon and/or
evening hours.

&&

.MARINE...
This Afternoon and Tonight: Surface high pressure will hold
strong over the local marine waters through tonight with SW
winds generally less than 15 knots. There could be some gusts to
around 20 knots this afternoon along the immediate coastline
associated with the sea breeze. Thunderstorms are possible again
this afternoon as land-based storms push offshore. Additional
thunderstorms are possible over the marine zones through the
overnight period. Frequent lightning and gusty winds will be the
main hazards. Seas through the period should average 2 to 3 ft.

Sunday through Wednesday: Expect generally southerly winds at 5 to
10 kt to prevail throughout the period. It could become a bit gusty
each afternoon with gusts up to 15 to 20 kt as the seabreeze pushes
inland (gusts strongest across the immediate coastline and the
Charleston Harbor). Southeasterly swell will continue to mix into
the local waters over through early next week. Seas will be 2 to 3
ft, then increase to 3 to 4 ft on Wednesday. Otherwise, no marine
concerns expected.

&&

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

&&

$$

NEAR TERM...NED
SHORT TERM...Dennis
LONG TERM...Dennis
AVIATION...NED
MARINE...CPM/Dennis