567
FXUS62 KCHS 101824
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
224 PM EDT Sun Aug 10 2025

.SYNOPSIS...
A stationary front will be south of our area through tonight,
while high pressure remains centered well to our north. The
stationary front should dissipate on Monday. By mid to late
week, the high will shift into the Atlantic, while weak
troughing forms inland.

&&

.NEAR TERM /THROUGH TONIGHT/...
Much like yesterday`s synoptic set up, broad mid-level weakness will
persist overhead while a stationary surface front remains oriented
along the Georgia and Carolina coasts. Through the rest of the day
and into tonight, vorticity will continue to pass over the area as
it rounds the western flank of the ridge located near Bermuda. The
atmosphere will remain extremely moist into tonight with PWATs
progged to approach 2.4-2.5" at times later this afternoon. As
impulses move through, scattered to numerous bands of light to
moderate showers will develop and push inland. The bulk of
deeper convection and thunderstorm activity will stay offshore
and along the immediate coastline where instability is greater.
Inland areas on the other hand, will remain less unstable
thanks to the nearby wedge of high pressure, with MLCAPE values
only peaking between 400-600 J/kg. Persistent cloud cover and
ongoing rainfall will help keep temperatures relatively cool
again, with highs mainly in the lower 80s. Some places across
the interior South Carolina counties may struggle to reach 80
degrees, although near the Altamaha River, highs could reach the
mid 80s.

Storm motions look stronger than yesterday, generally around 10-15
kt, but given the saturated grounds from several inches of rain over
the past few days, it will not take much additional rainfall to
trigger flooding. The greatest flood threat remains along the
coast where rainfall coverage will generally be higher. HREF
probabilities seem to have trended downward from the previous
run, showing pockets of 20-40% chance for greater than 2 inches
of rainfall and only 10% for 3+ inches. However, flooding
concerns will remain heightened through the night, particularly
with high tide expected around 940 PM, mainly along the
Charleston and Colleton County coasts where a Coastal Flood
Advisory has been issued. Additionally the Flood Watch in effect
for counties generally along/east of I-95 will continue through
the night. Flood Advisories or a base Flash Flood Warning could
become necessary later this afternoon/evening.

Tonight: This convective pattern will continue through tonight
with most of the activity refocusing over the Atlantic and
across the coastal counties by early Monday. Low temperatures
will fall into the lower 70s inland and mid to upper 70s along
the immediate coast/beaches.

&&

.SHORT TERM /MONDAY THROUGH WEDNESDAY/...
Monday: The 500 mb level will consist of a roughly 595 dam High off
the Southeast U.S. in the morning. It`s western periphery will
gradually build over our area during the evening and overnight. At
the surface, High pressure will be centered well to our north, near
New England. Meanwhile, a stationary front will be located south of
our area in the morning. It`s expected to dissipate during the day
or overnight. This pattern will continue to usher deep moisture
across the region with PWATs ranging from 2" to possibly as high as
2.5". The deterministic models and CAMs have numerous to widespread
showers during the day, gradually trending lower during the evening
and overnight. This is reflected in the NBM. For this reason, high
temperatures will remain below normal, generally in the low to mid
80s. This is also keeping instability rather low. Though, there are
signs that pockets of higher MLCAPEs and DCAPEs could be along the
Altamaha River. So a few stronger thunderstorms are possible in this
area, especially during the afternoon. But the overall severe risk
is very low. The main hazard remains locally heavy rainfall due to
the very moist environment. Additionally, storm motions should be
slow, with rain falling on already saturated ground. The models
point to the Charleston Tri-County having the highest potential for
heavy rainfall, as is highlighted at this typing in the WPC
Excessive Rainfall Outlook. But we opted to not make any extension
to the Flood Watch so far out, especially considering how much could
still change.

Tuesday and Wednesday: The 500 mb level will consist of a roughly
594 dam High centered just off the Southeast U.S. At the surface,
High pressure will shift into the Atlantic, while weak troughing
forms inland or just to our north. PWATs may creep a little lower
than on Monday, but generally still stay at or above 2". Overall, we
will see a shift back towards a more typical-summertime pattern.
High temperatures will rise, returning to near normal. Likewise,
heat indices will hit triple digits for some locations on Tuesday,
then most of our area on Wednesday. This will create enough
instability to generate scattered convection each afternoon,
followed be decreasing coverage in the evening and overnight. Strong
to marginally severe storms cannot be ruled out with damaging winds
and locally heavy rainfall.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/...
High pressure will dominate at the surface and aloft through the end
of the week and into the weekend. As the high pressure strengthens
temperatures will increase, reaching the low to mid 90s by Thursday.
This typical summer-time pattern will consist of hot and humid
conditions along with afternoon thunderstorms. Heat index values are
forecasted to be just shy of Heat Advisory criteria.

&&

.AVIATION /18Z SUNDAY THROUGH FRIDAY/...
KCHS/KJZI/KSAV: Moist conditions will persist across the region,
supporting scattered to numerous showers and potentially an
isolated embedded thunderstorm into Monday. Timing of direct
impacts remains uncertain due to the disorganized and transient
nature of convection. Also, chances for thunder remain low
enough to exclude from the latest TAF. As such, VCSH was
maintained at all terminals through the night, with the
potential for more organized bands arriving later this evening
and/or during the overnight hours. Brief IFR vsbys/cigs are
possible within heavier showers and future amendments could be
needed to account for TEMPO showers. Otherwise, MVFR cigs will
persist into the overnight, with gradual improvement expected
between early to mid Monday morning, though MVFR ceilings could
linger into the early afternoon.

Extended Aviation Outlook: Brief flight restrictions will be
possible due to afternoon showers/thunderstorms.

&&

.MARINE...
Through Tonight: A lingering coastal trough will result in
prevailing easterly winds with speeds around 15 kt. Seas will
average 2-4 ft. Mariners should be aware of numerous to
widespread showers and thunderstorms over the waters lasting
into early Monday morning, some of which could become capable
of producing an isolated waterspout.

Monday: High pressure will be centered well to our north, while a
stationary front south of our area should dissipate during the day
or overnight. This will generate SE winds 10-15 kt and seas 2-3 ft.

Mid to Late Week: The High will shift into the Atlantic, while weak
troughing forms inland. This will generate a more typical summertime
pattern. Expect backing winds with the formation of the afternoon
sea breeze. The highest gusts will be along the land/sea interface
and across Charleston Harbor (with its passage). Each night, expect
veering of the winds as a nocturnal jet tries to set up close to
shore. Seas will average 2-3 ft. No marine concerns are
expected.

&&

.TIDES/COASTAL FLOODING...
The recent full moon (8/9) has caused increased astronomical
tides, with onshore winds increasing them further. The
Charleston Harbor tide gauge is expected to peak around 7 ft
MLLW each evening through Monday. Coastal Flood Advisories could
be needed for Charleston and coastal Colleton counties.

A Coastal Flood Advisory has been issued for Charleston and Coastal
Colleton counties for tonight`s high tide which is expected to peak
between 7.1-7.3 ft MLLW.

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Flood Watch through late tonight for GAZ101-116>119-138>141.
SC...Flood Watch through late tonight for SCZ042>045-047>052.
     Coastal Flood Advisory from 8 PM to 11 PM EDT this evening for
     SCZ049-050.
MARINE...None.

&&

$$

NEAR TERM...
SHORT TERM...
LONG TERM...
AVIATION...
MARINE...