781
FXUS62 KCHS 312356
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
756 PM EDT Fri Jul 31 2026

.WHAT HAS CHANGED...
Aviation section has been updated to reflect the 00Z aviation
package.

&&

.KEY MESSAGES...
- 1) Isolated to scattered thunderstorms are expected to
  develop along the sea breeze this afternoon. These
  thunderstorms will be capable of producing gusty winds,
  locally heavy rainfall, and cloud to ground lightning.

- 2) Warm and humid coniditons will remain across southeast
  Georgia and the South Carolina Lowcountry this weekend. This
  environment will support scattered to numerous thunderstorm
  each afternoon and evening. Some of these slow- moving storms
  may produce localized excessive rainfall and gusty winds.

&&

.DISCUSSION...
KEY MESSAGE 1: Isolated to scattered thunderstorms are expected
to develop along the sea breeze this afternoon. These
thunderstorms will be capable of producing gusty winds, locally
heavy rainfall, and cloud to ground lightning.

The front that has been in/near the region the past couple days
remains draped across our southeast GA counties, with a weak low
pressure expected to remain along the front. Aloft, weak
northwesterly flow will continue throughout the day. This pattern
will continue the near-normal temperatures today, with highs in the
lower to mid 90s across the area. Dewpoints for inland areas have
mixed out into the mid to upper 60s, keeping heat index values in
the mid 90s. Areas along/near the coast are expected to keep
dewpoints in the lower to mid 70s, resulting in heat index values in
the upper 90s to lower 100s.

The afternoon sea-breeze in combination with the weak aforementioned
surface low is expected to continue and expand the coverage of the
ongoing showers and thunderstorms into the rest of the afternoon
hours. The environment today is progged to have 1500-2000 J/kg of
MLCAPE, though weak 700-500mb lapse rates and weak flow aloft will
keep the threat for strong-severe thunderstorms low. However, with
dry mid-upper levels the DCAPE values are in the 1000-1500 J/kg
range, bringing a low chance for strong wind gusts to near 50 mph.
While PWATs are rather low in the 1.2-1.6" range, the weak flow
aloft will keep storm motions rather slow, resulting in locally
heavy rainfall being possible, which also aids the chances for
strong wind gusts. Convection will likely struggle to spread inland
thanks to the aforementioned lower dewpoints. Storms should mostly
run their course by the late afternoon and steadily dissipate
through the early evening hours.


KEY MESSAGE 2: Warm and humid coniditons will remain across southeast
Georgia and the South Carolina Lowcountry this weekend. This
environment will support scattered to numerous thunderstorm each
afternoon and evening. Some of these slow-moving storms may produce
localized excessive rainfall and gusty winds.

Saturday: High resolution guidance indicates that a weak warm front
will approach from the south tonight. Recent runs of the HRRR
suggest that the warm front could reach the Altamaha River during
the pre-dawn hours Saturday morning. 12Z run of the HREF indicates
that PW values will continue to increase through the daylight hours
on Saturday. By Saturday afternoon, PW values should exceed 2 inches
across southeast GA and between 1.8 to 2 inches across the SC
Lowcountry. Forecast soundings indicate only a weak subsidence
inversion, as a closed low settles over the Ohio River Valley. As a
result, surface-based CAPE may exceed 2,500 J/kg along the coast and
between 1,500 and 2,000 J/kg inland. This environment should allow
isolated to scattered storms to develop along the sea breeze early
Saturday afternoon. Storm coverage should peak across southeast GA
late Saturday afternoon and evening as a thunderstorm cluster and
associated cold pool sourced from central GA interacts with the sea
breeze over the I-16 corridor between Metter, GA and northern
Chatham County. Storms across southeast GA may only have storm
motions of 10-15 miles an hour. The slow storm motions combined with
deep atmospheric moisture could lead to localized areas of 2-4
inches of rainfall. HREF 3-hour QPF probabilities highlights the I-
16 corridor with up to a 30% chance of 3 inches in a 3-hour period.
These rainfall rates may require Flood Advisories and possibly Flash
Flood Warnings. Temperatures will remain seasonable with highs in
the low to mid-90s.

Sunday: Forecast area will remain between an H5 closed low over KY
and TN and a very strong ridge centered over Bermuda. At the
surface, a broad area of low pressure will remain across SC.
Forecast soundings indicate that deep moisture will persist across
the region. However, thick cloud cover and falling mid-level heights
should limit instability to 1,000 J/kg or less. The combination of
surface moisture convergence within the broad trough and afternoon
sea breeze should trigger scattered to numerous showers and
thunderstorms. Some high-resolution guidance indicates clusters of
thunderstorms over south-central GA could drift into southeast GA in
the late afternoon hours. These storms should develop the tallest
updrafts and may possess some severe wind gust threat. SPC has
highlighted this area with a Marginal Risk for severe
thunderstorms.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
00Z TAFs - VFR conditions will prevail throughout the night now
that storms have diminished across the area with light
southeasterly winds. Chances for isolated showers and
thunderstorms return Saturday morning along the Charleston
county coastline; however, coverage is too uncertain at this
time to warrant mentioning in the CHS or JZI TAFs. Storm
coverage should increase and expand to the south into the
afternoon hours with temporary restrictions will be possible
within any thunderstorms that do develop. Have added a TEMPO
group to SAV and PROB30 to CHS to reflect the increase in
thunderstorm and impacts to aviation during the mid to late
afternoon hours.

Extended Aviation Outlook: The probabilities for periodic flight
restrictions due to showers and thunderstorms will increase this
weekend into early next week.

&&

.MARINE...
Through tonight: A stationary front will remain draped across the
Southeast and extend into the local waters through tonight. This
will support relatively light winds with seas generally around 1 to
2 ft.

This weekend through Wednesday: Pressure gradient will gradually
increase across marine zones Saturday into Sunday. Sea and wind
conditions should remain below Small Craft Advisory criteria on
Saturday. Wind gusts in excess of 25 knots may develop across the
near and outer waters by late Sunday afternoon into Sunday night. In
addition, wave heights are forecast to increase to 4-6 feet Sunday
night, Small Craft Advisories are possible. Conditions should
gradually improve on Monday, with benign wind and sea conditions
expected for Tuesday into Wednesday.

Rip Currents: A moderate risk of rip currents have been posted for
the SC coast for Sunday. Rip currents may result from gusty
southwest winds and building swell between 6 to 9 seconds.

&&

.CLIMATE...
Record High Minimum Temperatures:

August 1:
KCHS: 81/1999
KCXM: 86/1999
KSAV: 79/2020

August 6:
KCHS: 79/1991
KCXM: 82/2006
KSAV: 80/1899

&&

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

&&

$$

APT/Black/NED