Severe Thunderstorm Warning 40, NWS Charleston, SC

Area Forecast Discussion
National Weather Service Charleston SC
138 PM EDT Tue Jul 7 2026

.WHAT HAS CHANGED...
All Key Messages and Sections were updated. An Excessive Heat
Watch has been issued for the coastal corridor on Wednesday,
including both the Charleston and Savannah Metro areas, with a
Heat Advisory for much of interior Southeast Georgia into
Southeast South Carolina.

&&

.KEY MESSAGES...
- 1) Heat and humidity will continue across southeast Georgia
  and the South Carolina Lowcountry today. Strong to severe
  thunderstorms are possible along and east of I-95 this
  afternoon and evening. Heavy downpours could lead to pockets
  of excessive rainfall.

- 2) Hot and humid conditions will persist through much of the week.

- 3) Typical summertime afternoon and evening thunderstorms this
  week.

&&

.DISCUSSION...

KEY MESSAGE 1: Heat and humidity will continue across southeast
Georgia and the South Carolina Lowcountry today. Strong to severe
thunderstorms are possible along and east of I-95 this afternoon and
evening. Heavy downpours could lead to pockets of excessive rainfall.

Another hot day prevails across the region under mostly sunny
skies, with latest observations showing temperatures in the low
to mid 90s. This coupled with dewpoints in the low to mid 70s
has resulted in heat index values between 105 to 110 degrees,
with the highest values noted along the coast. Given that cloud
cover and precipitation chances are forecast to increase through
the afternoon, do not plan to make any changes to the current
Heat Advisory, which remains valid until 7 PM.

As noted in the previous discussion, these hot and humid conditions
are expected to result in scattered showers and thunderstorms, a few
of which could become strong to severe. In terms of dynamics, latest
soundings show MUCAPE between 1500 to 2500 J/Kg, low level lapse
between 7.5 to 8 deg C/km, and bulk shear values near 15 to 20 kts.
DCAPE values also look to gradually increase between 800 to 1000
J/kg. Thus, in terms of severe weather, expect damaging winds, small
hail, and frequent lightning to be the primary hazards with any
storm. In addition, storm motions around 10 mph and PWATs around 2.2
inches will likely lead to swaths of heavy rainfall between 2-3
inches. While the threat for flash flooding remains low, a few flood
advisories may still be needed for some coastal SC/GA counties,
including Berkeley County. Otherwise, should see convection quickly
wane near sunset, with overnight lows forecast to remain in the mid
to upper 70s.

KEY MESSAGE 2: Hot and humid conditions will persist through much of
the week.

The heat and humidity will build Wednesday as ridging aloft
strengthens. 850 hPa temperature are forecast to warm to 20-22C with
low-thicknesses peaking 1437-1440 meters. These values typically
support highs within a 1-2 degrees either side of 100 degrees.
Dewpoints are expected to mix out somewhat (lower-mid 70s) during
the afternoon, but dewpoint pooling (upper 70s/lower 80s)
near/behind the sea breeze should push heat indices to dangerous
levels across parts of the coastal corridor with max heat indices
peaking in the 112-116 degree range for several hours. Farther
inland, heat indices should generally peak 105-110 range. Given the
above noted trends, an Excessive Heat Watch has been posted for the
coastal corridor, including both the Charleston and Savannah Metro
areas, with a Heat Advisory for much of interior Southeast Georgia
into Southeast South Carolina. Only the area from Jenkins County to
Hampton County look to fall short of the 108 heat index criteria for
a Heat Advisory. Warming temperatures aloft will help limit
afternoon convection with only isolated coverage expected. There are
some CAMs that support a bit more coverage so this will need to be
watched as some areas could fall short of warning/advisory criteria
if convection becomes more scattered.

Heat is expected to continue through the end of the week with
heat indices likely around the 105 to 110 range and highs in the
mid to upper 90s area wide. Heat products look to continue at
least through Thursday and possibly into Friday with the highest
probability of reaching advisory criteria mainly east of I-95
and closer to the coast including the Charleston and Savannah
metro areas. While heat indices may not be as high as early
week, the bigger issue will be long duration heat stress mainly
along the coastal areas where heat indices might not drop to
below 100 degrees until well into the evening and overnight
hours with lows in the upper 70s to low 80s. Several days of
intense heat and minimal cooling overnight has been reflected in
the HeatRisk product with widespread Major (level 3 of 4) and a
corridor of Extreme (level 4 of 4) along the immediate coast
Thursday and Friday. Regardless of any heat products this will
continue to bring a risk of heat-related impacts, especially to
those more vulnerable to heat or those without adequate
cooling/hydration.

KEY MESSAGE 3: Typical summertime afternoon and evening
thunderstorms this week.

The region will be situated between high pressure offshore and a
trough of low pressure inland through much of the week, with ridging
the primary feature aloft. Larger scale forcing is lacking, but
isolated to perhaps scattered showers and thunderstorms will be
possible each day largely due to daytime heating and mesoscale
boundaries like the sea breeze. Coverage will be highest in the
afternoon and early evenings, before dwindling after sunset with
loss of insolation. While the environment favors mainly pulse-type
convection, a couple strong to severe storms with damaging wind
gusts cannot be ruled out. Locally heavy rainfall is also possible
with any storms, but flooding risk is low especially given the hot
and dry conditions of late.

Rain chances will likely increase Sunday into Monday as a more
potent shortwave trough moves across the mid-atlantic. Expect
storm coverage to increase Sunday afternoon compared to the
normal summertime pattern. Storms will likely be focused along a
sagging front that will slowly drift south with time. Given the
increased coverage and maybe a little more deep layer flow, a
couple strong to severe storms with damaging winds may be
possible on Sunday.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Rain chances will likely increase Sunday into Monday
as a more potent shortwave troughs move across the mid-atlantic.
Expect storm coverage to increase Sunday afternoon compared to the
normal summertime pattern. Storms will likely be focused along a
sagging front that will slowly drift south with time. Given the
increased coverage and maybe a little more deep layer flow, a couple
strong to severe storms with damaging winds may be possible on
Sunday.

Extended Aviation Outlook: There will be a risk for tstm impacts at
the terminals each afternoon/evening, especially at KCHS and
KSAV.

&&

.MARINE...
Through Tonight: This afternoon and evening, strong thunderstorms
may slide off the GA/SC coast. Some of these storms may require
Special Marine Warnings. Otherwise, the pressure pattern should
support south-southwest winds between 15 to 20 kts, with occasional
gusts to 25 kts. Wave heights are forecast to favor 3 to 4 ft.

Wednesday: A southerly flow regime will prevail with some sea breeze
enhancements likely along the land/sea interface and Charleston
Harbor where gusts near 20 kt will be possible. A typical summer
time nocturnal surge will impact the area Wednesday night with south
to southwest winds 15-20 kt. Gusts could near 25 kt at times, but
durations do not quite look frequent enough for a Small Craft
Advisory at this time.

&&

.CLIMATE...
Record High Temperatures:

July 8:
KCHS: 100/2016
KSAV: 101/2010

July 10:
KCHS: 100/1986
KCXM: 99/1986

July 11:
KCXM: 100/2001

July 12:
KCXM: 97/1966

Record High Minimum Temperatures:

July 7:
KCHS: 80/2017
KCXM: 82/2022
KSAV: 80/1883

July 8:
KCHS: 82/2016
KCXM: 83/2016
KSAV: 80/1990

July 9:
KCHS: 80/1998
KCXM: 85/1998
KSAV: 80/1883

July 10:
KCHS: 81/1986
KCXM: 82/1986

July 11:
KCHS: 80/2016
KCXM: 82/2016

July 12:
KCHS: 79/2020
KCXM: 82/1998

&&

.CHS WATCHES/WARNINGS/ADVISORIES...
GA...Heat Advisory from 11 AM to 7 PM EDT Wednesday for GAZ099>101-
     114-115-137-216-238-240.
     Heat Advisory until 7 PM EDT this evening for GAZ217>219-239-
     241.
     Extreme Heat Watch from Wednesday morning through Wednesday
     evening for GAZ217>219-239-241.
SC...Heat Advisory from 11 AM to 7 PM EDT Wednesday for SCZ043-044-
     147.
     Heat Advisory until 7 PM EDT this evening for SCZ045-148>152.
     Extreme Heat Watch from Wednesday morning through Wednesday
     evening for SCZ045-148>152.
MARINE...None.

&&

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>

<!doctype html>
<html lang="en">
<head>
  <meta charset="utf-8">
  <meta name="viewport" content="width=device-width, initial-scale=1">
  <title>Service Notice</title>
  <link rel="stylesheet" href="index.css">
</head>
<body>
  <main class="wrap">
    <section class="card" role="status" aria-live="polite">
      <div class="status" id="status">Temporary Notice</div>
      <h1 id="headline">This service is currently unavailable.</h1>
      <p id="message1">
        The site you requested is temporarily down for maintenance or an unexpected outage.
      </p>
      <p id="message2">
        Please try again in a few minutes.
      </p>
      <p class="small" id="detail">
        If you are an administrator, restore upstream service and remove the redirect/fallback rule when normal operations resume.
      </p>
    </section>
  </main>
  <script src="index.js"></script>
</body>
</html>