861
FXUS62 KCHS 111107
AFDCHS

Area Forecast Discussion
National Weather Service Charleston SC
707 AM EDT Tue Aug 11 2026

.WHAT HAS CHANGED...
The Aviation section was updated for the 12Z TAFs.

&&

.KEY MESSAGES...
- 1) A Heat Advisory is in effect for the coastal counties this
  afternoon as hot and humid conditions make a return.
  Additional Heat Advisories will likely be required through the
  week and into the weekend. Extreme Heat Watches/Warnings
  cannot be ruled out, especially towards the end of the week.

- 2) Scattered to numerous thunderstorms will develop across
  southeast Georgia and the lower South Carolina Lowcountry,
  especially near the coast. A few storms may produce damaging
  wind gusts and heavy downpours this afternoon and evening.
  Additional severe thunderstorms are possible across portions
  of the region late Wednesday.

&&

.DISCUSSION...
KEY MESSAGE 1: A Heat Advisory is in effect for the coastal
counties this afternoon as hot and humid conditions make a return.
Additional Heat Advisories will likely be required through the week
and into the weekend. Extreme Heat Watches/Warnings cannot be ruled
out, especially towards the end of the week.

Heat headlines are likely into the weekend as heat index values soar
into the 100-110 range each afternoon through mid-week and upwards
of 115 late in the week. The daily record highs and record high
minimum temperatures will likely be challenged at our three climate
sites (see Climate Section for more details). Given the very mild
overnight periods and minimal coverage of precipitation, there will
be few instances of relief from the heat this week and into the
weekend.

Today and Wednesday: Ridging aloft will dominate over the
southeastern states today and Wednesday, with high temperatures each
day reaching into the mid 90s. Dew points will surge behind the sea
breeze, likely reaching values in the mid to upper 70s. This will
yield heat index values as high as 110 generally east of I-95. A
Heat Advisory is in effect for the coastal counties today from 11 AM
to 8 PM. Another Heat Advisory will likely be required for the same
locations on Wednesday.

Thursday and Friday: The ridging aloft amplifies towards the end of
the week, likely bringing the warmest temperatures of the heat wave.
Highs on each day will likely reach into the upper 90s, with a brief
moment of touching 100 not out of the question. Heat index values
west of I-95 will likely reach 105-108 (Heat Advisory) with
locations east of I-95 reaching heat index values as high as 115.
Extreme Heat Watches/Warnings may be required for these locations.

This Weekend: The center of ridging aloft will shift slightly
westward, resulting in a slight downtick of temperatures. However,
heat index values are still forecast to reach upwards of 110 along
the coastal corridor likely necessitating additional Heat
Advisories.

KEY MESSAGE 2: Scattered to numerous thunderstorms will develop
across southeast Georgia and the lower South Carolina Lowcountry,
especially near the coast. A few storms may produce damaging wind
gusts and heavy downpours this afternoon and evening. Additional
severe thunderstorms are possible across portions of the region late
Wednesday.

Tuesday: A sfc trough should remain across the central Carolinas
into GA through this evening. Satellite water vapor shows an MCV
over the middle AL/GA this morning, expected to ripple over SE GA
this afternoon. In addition, the sfc trough to the west should draw
the sea breeze inland this afternoon. Recent run of the HREF
indicates that deep convection may begin to develop ahead of the
MCV, likely forming several cool pools. Hot and humid conditions
across the forecast area will likely yield SBCAPE values between
2500-3000 J/kg. In addition, forecast soundings indicate DCAPE
values between 1000-1500 J/kg. Given the expansive field of DCAPE,
the cool pools should travel long distances, potentially interacting
with the sea breeze. This interaction should develop scattered to
numerous thunderstorms along the coast, especially between Chatham
and Charleston counties. The environment featuring moderate
instability and DCAPE along with effective bulk shear around 20 kts
may support a few severe thunderstorms, producing damaging wind
gusts. The severe potential appears the greatest across Chatham,
Jasper, Beaufort, and Colleton counties this afternoon. In fact, 0Z
GEFS indicates that most of the forecast has a 5-15% neighborhood
prob of damaging winds, with in excess of 15% near the mouth of the
Savannah River. In addition to the severe risk, multicell storms may
produce localize areas of heavy rainfall, with some locations
receiving in excess of 3 inches. If a swath of heavy rain occurs
over a coastal city, then Flash Flooding may occur.

Wednesday: The center of 595 DM ridge is forecast to slide west over
the northern Gulf. As a result, NW to SE heights may align over the
forecast area. NAM12 and CAMS indicate that at least isolated storms
may develop over portions of SE GA Wednesday afternoon.
Interestingly, the NAM12 and GFS shows an MCS tracking from the
Upstate to the Coastal Plain Wed evening. Given the mid-level
heights and lingering elevated instability, the potential for an MCS
reaching the forecast appears high enough to increase PoPs Wednesday
evening and overnight to at least SCHC. SPC has highlighted this
potential severe weather with a Marginal Risk.

&&

.AVIATION /12Z TUESDAY THROUGH SATURDAY/...
12Z TAFs: The terminals will remain between a broad trough
across the central Carolinas and Georgia and high pressure over
the western Atlantic. This pattern will yield west-southwest
winds across the terminals through the TAF period. The
interaction of cold pools from the NW and a sea breeze should
spawn scattered to numerous thunderstorms near KSAV, highlighted
with a TEMPO from 20-24Z. Coverage of convection near KJZI and
KCHS appears a bit less compared to KSAV, TAFs will highlight
the primary thunderstorm time window with a PROB30 between
20-24Z.

Extended Aviation Outlook: Prevailing VFR.

&&

.MARINE...
The pressure pattern will support south winds between 15 to 20 kts
today, shifting from the southwest tonight. Wave heights are
forecast to remain between 2 to 3 ft. Scattered to numerous
thunderstorms may push over the nearshore waters late this afternoon
and evening. A few of these storms may produce wind gusts in excess
of 34 kts, especially the nearshore GA and lower SC waters.

Wednesday through Saturday: Conditions are expected to remain below
Small Craft Advisory criteria this week and into the weekend. A weak
coastal trough will set up across the marine waters this week,
persisting into the start of the weekend. This set up will keep
conditions across the marine waters breezy with southwesterly winds
gusting around 15 to 20 knots. 2 to 3 ft seas are expected across
the marine zones this week.

Coastal Flooding: While elevated tidal cycles are expected this
week due to the upcoming perigee and new moon, the south-
southwesterly surface flow should keep tidal departures low,
limiting the overall coastal flood threat.

&&

.CLIMATE...
Record High Temperatures:

August 11:
KCHS: 98/1968
KCXM: 97/1954

August 12:
KCHS: 98/1957
KCXM: 98/1998
KSAV: 100/1999

August 13:
KCHS: 100/1995
KCXM: 98/1913
KSAV: 98/2010

August 14:
KCHS: 102/1995
KSAV: 102/1925

August 15:
KCHS: 96/2023
KSAV: 100/1918

Record High Minimum Temperatures:

August 10:
KCHS: 80/2007
KSAV: 79/2024

August 11:
KCHS: 79/1983
KCXM: 82/2021
KSAV: 78/1878

August 12:
KCHS: 79/1999
KSAV: 80/1878

August 13:
KCHS: 81/2023
KCXM: 83/2023
KSAV: 81/2023

August 14:
KCHS: 80/2023
KCXM: 83/2023
KSAV: 80/2023

August 15:
KCHS: 78/1995
KCXM: 83/2021
KSAV: 80/1995

August 16:
KCHS: 78/2019
KSAV: 78/2019

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
     for GAZ217>219-239>241.
SC...Heat Advisory from 11 AM this morning to 8 PM EDT this evening
     for SCZ148>152.
MARINE...None.

&&

$$

CPM/NED