451
FXUS62 KCHS 031836
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
236 PM EDT Sun Aug 3 2025

.SYNOPSIS...
A stationary front will linger in the vicinity of the area
through at least the middle of the week.

&&

.NEAR TERM /THROUGH TONIGHT/...
Rest of today: Aloft, a broad and gradually amplifying trough
spread from the Midwest and Central Plains to the Mid-Atlantic
will prevail. At the surface, a wedge of stable/cooler high
pressure has settled inland. Also, a stationary front lies
draped just north of the FL/GA border, which will serve as the
primary forcing mechanism for scattered to numerous
shower/thunderstorm activity today. Additionally, weak shortwave
activity embedded in the flow aloft could provide supplementary
lift to aid in convection in the form of showers across the SC
Midlands and LowCountry. High temps will range from the low to
mid 80s most places, with some far inland locations struggling
to reach 80 degrees and only reaching the upper 70s.

The threat for strong to severe storms remains low due to very weak
instability across much of the region with cooler air present.
A tight instability gradient exists along the front, with
minimal CAPE values across the bulk of the forecast area. The
exception lies in portions of McIntosh, Long, and coastal
Liberty counties, where SBCAPE peaks around 1500 J/kg.
Elsewhere, SBCAPE values remain well below 900 J/kg.
Therefore, a few thunderstorms are possible in the
aforementioned counties with mainly showers elsewhere.

As for rainfall, PWATs near 2.25 inches coupled with slow storm
motions (5-10 kt) indicate the potential for prolonged periods of
moderate to locally heavy rainfall in some locations. Scattered
light to moderate showers will persist across most of the area
today, but the deepest convection and thus the greatest rainfall
amounts will be confined mainly to areas south of I-16 and the
immediate coast, particularly south of Charleston. These areas lie
along/near the axis of greatest instability and low level
convergence. HREF indicates 30-40% probabilities of 2 inches or
greater rainfall falling from between the Edisto Beach area
south toward Hilton Head/Savannah, and into McIntosh, Long, and
Liberty counties. For totals exceeding 3 inches, HREF places a
bullseye on McIntosh County where probs range 60-70%. Although
widespread rainfall amounts are not particularly impressive, we
cannot rule out an isolated locally heavy rainfall and flash
flooding threat especially for the aforementioned areas, and where
some places have already received multiple inches of rainfall
in the last 24 hours. Flood Advisories and/or Flash Flood
Warnings could eventually be needed in the evening or later
tonight.

Tonight: Much of the same is expected tonight with perhaps
slight northward movement in the positioning of the front. This
could help push an area of numerous to widespread convection
from southern Georgia northward into the forecast area late and
keep activity persistent through at least the first half of the
night. Cool temperatures are on tap again tonight with lows in
the upper 60s/lower 70s inland and mid 70s along the immediate
coast.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
Monday through Wednesday: Aloft, the forecast area will be situated
ridging to the east and a trough that is expected to slowly advance
east of the MS Valley. At the surface, high pressure will continue
to hold east of the Appalachians with a stationary boundary to the
south across south GA and north FL, as well as the potential for an
area of low pressure to develop well off the coast Tuesday into
Wednesday. Through the early to mid week time period, the stationary
boundary situated to the south should be the main focusing mechanism
for shower and thunderstorm development. So while the front will
likely meander around a bit, as well as the zone of highest
moisture, the highest thunderstorm coverage and best potential for
locally heavy rainfall should favor the southern half of the area
including southeast GA each day. But, showers and thunderstorms will
be possible across the entire area each afternoon and evening given
the moist airmass. The severe threat doesn`t look particularly
noteworthy given the lack of significant instability each day.
Temperatures should continue to run below normal for Monday with low
to mid 80s, then back closer to normal Tuesday and Wednesday as
upper 80s become more common.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
As we head into the late week and into the weekend time period,
Atlantic ridging will attempt to build back to the west and into the
Southeast. At the surface, model guidance continues to suggest high
pressure inland and north, with a subtle boundary situated somewhere
along or near the coast. In fact, there could even be weak low
pressure development off the coast late in the week that shifts
northward through the weekend. We will maintain daily chances of
showers and thunderstorms, with some degree of a locally heavy
rainfall threat thanks to the presence of plentiful moisture and the
aforementioned boundary. Temperatures should gradually trend warmer,
back to near normal by the weekend.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
18Z TAF Discussion: A stationary front located south of the
Altamaha River, in addition to weak forcing aloft, will maintain
scattered to numerous showers across the forecast area through
the majority of the night. However, a wedge of cooler high
pressure positioned inland is keeping instability weak, thereby
limiting deep convection. The greater coverage is expected
across southeast Georgia, thus VCSH carries through the KSAV
TAF with the exception of prevailing SHRA which look best to
impact KSAV during the evening hours when the front could
possibly nudge northward. Activity should remain in the form of
showers with the exception of thunderstorms possibly developing
near KSAV or offshore the Charleston County coast. Confidence
in this occurring however is relatively low, therefore we have
no mention of TS in the current TAFs. Otherwise, KCHS and KJZI
should remain mostly VFR through the period, although there
could be times cigs dip below 3 kft. These time frames will need
to be sorted out with later TAF issuances/possible amendments.
MVFR cigs are more likely to prevail at KSAV with persistent
showers at least nearby, although ceilings could lower to IFR at
times.

Extended Aviation Forecast: Scattered to occasionally numerous
showers and thunderstorms will continue to provide the main
potential for brief flight restrictions through the middle of
the week.

&&

.MARINE...
Today and Tonight: A stationary front lies draped slightly north of
the FL/GA border with high pressure wedged inland, meanwhile an
area of low pressure to the north will continue riding roughly
within the northeast flowing Gulf Stream out into the Atlantic.
Northeast winds will prevail through tonight in the 10-15 kt
range, peaking near 20 kt at times this afternoon. Gusts could approach
25 kt at times, especially this afternoon and evening, but
should remain below Small Craft Advisory criteria. Scattered to
numerous showers and thunderstorms are likely across the local
marine zones this afternoon through most of the night, most of
which should be weaker in nature. Seas will average 3-5 feet,
before diminishing to 2-4 ft by daybreak Monday.

Monday through Friday: Overall, the setup is pretty quiet across the
local waters this week with conditions remaining below Small Craft
Advisory thresholds. Monday should bring the most elevated winds and
seas as northeast flow peaks around 15 knots with gusts up to 20
knots at times. Seas will average 2-4 feet through Monday night.
Thereafter, the gradient is expected to relax while winds remain out
of the northeast for much of the period (mostly in the 10-15 knot
range). Seas should diminish a bit, but still remain 2-3 feet
through the week.

Rip Currents: Some elevated swell and continued northeast flow will
yield a Moderate Risk of rip currents for the GA beaches on
Monday.

&&

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

&&

$$

NEAR TERM...BRS
SHORT TERM...BSH
LONG TERM...BSH
AVIATION...BRS/BSH
MARINE...BRS/BSH