434
FXUS62 KCHS 311800
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
200 PM EDT Thu Jul 31 2025

.SYNOPSIS...
Atlantic high pressure will extend across the region tonight. A
cold front may stall nearby this weekend.

&&

.NEAR TERM /THROUGH TONIGHT/...
Convection has been pretty sparse so far today with some degree
of capping/subsidence noted from the upper-level anticyclone
centered just offshore of Cape Canaveral. RAP modified
soundings do show the cap eventually being overcome over the
next few hours, but model 850 hPa theta-e values will fairly
low considering the time of year. This suggests the mid-levels
may be a bit too dry to support a significant amount of
convection. Pops were lowered slightly given this trend,
favoring more of the 20-40% range, highest across the interior.
Convection will slowly wane through the evening hours, but an
isolated shower/tstm could spark just about anywhere overnight,
especially near any lingering convective outflow boundaries.

The current placement/timing of the Heat Advisory and Extreme
Heat Warning are on target. Heat indices are already
approaching advisory levels at the coast and some spots inland,
but as temperatures continue to rise and dewpoints pool into the
upper 70s/lower 80s with the afternoon sea breeze, expect a few
hours of heat indices in the 112-116 range across the coastal
counties. Max heat indices should peak 108-112 farther inland.
Debris cloudiness from earlier convection off the northeastern
South Carolina coast have modulated temperatures slightly over
Berkeley and Charleston Counties, but temperatures and heat
indices should recover to the the forecasted maxima as these
high clouds steadily thin.

Warm and muggy conditions will persist overnight. Lows will
range from the mid 70s well inland to the upper 70/lower 80s at
the coast and beaches. The high minimums for August 1 could be
challenged tonight, mainly at KCHS and KSAV, although convection
Friday could push temperatures below these records. The record
high minimum of 86 (last set 1999) in Downtown Charleston looks
safe.

&&

.SHORT TERM /FRIDAY THROUGH SUNDAY/...
At the surface, a reasonably strong cold front for early August
will start to push into the region at the leading edge of this
aforementioned upper-lvl trough on Friday. Ample moisture and
instability will promote heavy to excessive rainfall in showers
and/or thunderstorms that could cause localized flash flooding
through early next week. Heaviest period of rainfall look to be
Saturday afternoon into Sunday night, as the front settles
nearby. Axis of the front will wobble over the next couple days,
and might make minor changes to the precipitation totals. The
latest 7-day QPF graphic shows 4 to 6 inches of rainfall across
the region (with 6 to 8 inches over McIntosh County), with the
majority of these values falling Saturday through Monday. In
addition, WPC has placed the a portion of the region under a
Slight Risk for excessive rainfall on Friday and Saturday. In
regard to temperatures, expect highs to reach into the mid to
upper 90s on Friday with dewpoints ranging in the mid to upper
70s. A Heat Advisory was issued for tomorrow (11AM to 8PM EDT)
for counties along and east of I-95 as heat indices are expected
to reach into the 108 to 112 degrees range. It looks like
heating will peak ~2PM before showers and/or thunderstorms
develop across the region ~4-5PM and add some relief from the
heat. As this cold front continues to drop southeastward across
the region, temperatures will finally cool down on Saturday,
with highs only reaching into the mid to upper 80s across
southeast South Carolina and upper 80s to low 90s across
southeast Georgia. This will be enough to limit heating
Saturday, and an additional Heat Advisory will likely not be
needed. Heading into Sunday, temperatures will cool down even
more and only reach into the upper 70s to low 80s.

&&

.LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/...
This wet and unsettled pattern will continue through mid-week
as this cold front stalls nearby and meanders along the
coastline. With PWATs 2.0+ inches and decent instability
sticking around, scattered convection across the region should
be maintained. Periods of locally heavy rainfall will be
possible within these showers and/or thunderstorms that track
over an area for an extended period of time. On a positive note,
this pattern will allow for a refreshing change of cooler
temperatures through early next week.

&&

.AVIATION /16Z THURSDAY THROUGH MONDAY/...
31/18z TAF Discussion:
KCHS/KJZI/KSAV: VFR through 18z Friday. There are low chances
for tstms at both KCHS and KSAV this afternoon, but
probabilities look too low to mention at this time.

Extended Aviation Forecast: As a reasonably strong cold front
stalls nearby this weekend, brief flight restrictions will be
possible as showers and/or thunderstorms develop along this
boundary through early next week.

&&

.MARINE...
Tonight: There are no concerns. Southerly winds will veer to the
southwest tonight. Speeds will generally remain 15 kt or less
with seas 1-3 ft, building to 2-4 ft.

Friday through Monday: Expect southerly winds at 10 to 15 kt on
Friday, with winds turning to the northeast over the weekend as
a reasonably strong cold front for early August stalls nearby
over the weekend. It could become gusty over the weekend
(especially on Sunday) across the nearshore South Carolina
waters as the gradient pinches behind the cold front. Thanks to
this cold front, a northeasterly windswell will build on Sunday
and allow for a decent surf to set up at the local beaches.
Expect seas to be 2 to 3 ft on Friday and Saturday , and then
begin to build 4 to 6 ft on Sunday morning (mainly across South
Carolina nearshore waters). A Small Craft Advisory might be
needed for the nearshore Charleston waters (AMZ350) on Sunday.
This swell might be slow to exit through next week.

&&

.CLIMATE...
The low temperature observed so far at KCHS is 80 degrees. If
this temperature holds through 1 AM August 1, this will tie the
record high minimum for the late, last set in 2022.

Record High Minimum Temperatures:

August 1:
KCHS: 81/1999
KSAV: 79/2020

Record Precipitation:

August 2:
KSAV: 1.81/1990

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory until 8 PM EDT this evening for GAZ087-088-
     099>101-114>116-137-138-140.
     Heat Advisory from 11 AM to 8 PM EDT Friday for GAZ116>119-
     137>141.
     Extreme Heat Warning until 8 PM EDT this evening for
     GAZ117>119-139-141.
SC...Heat Advisory until 8 PM EDT this evening for SCZ040-042>045-
     047.
     Heat Advisory from 11 AM to 8 PM EDT Friday for SCZ048>052.
     Extreme Heat Warning until 8 PM EDT this evening for
     SCZ048>052.
MARINE...None.

&&

$$