704
FXUS62 KCHS 161823
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
223 PM EDT SUN AUG 16 2026
WHAT HAS CHANGED
THE AVIATION SECTION HAS BEEN UPDATED FOR THE 18Z TAF ISSUANCE.
KEY MESSAGES
- 1) HEAT WILL REMAIN A CONCERN THROUGH THE MIDDLE OF THE WEEK.
- 2) A FEW ISOLATED STRONG TO SEVERE THUNDERSTORMS ARE POSSIBLE
THIS AFTERNOON.
DISCUSSION
KEY MESSAGE 1: HEAT WILL REMAIN A CONCERN THROUGH THE MIDDLE OF
THE WEEK.
REST OF TODAY: AS AMPLIFIED RIDGING REMAINS IN PLACE ACROSS THE
DEEP SOUTH AND THE SOUTHEASTERN CONUS, AFTERNOON TEMPERATURES
WILL REACH INTO MID TO UPPER 90S WITH LOW 90S ALONG THE
COASTLINE. THESE TEMPERATURES COMBINED WITH DEWPOINTS IN THE MID
TO UPPER 70S (HIGHEST ACROSS THE COASTAL COUNTIES) YIELD HEAT
INDEX VALUES IN THE 105 TO 112 RANGE. THUS, A HEAT ADVISORY
SHALL REMAIN ACROSS THE LOWCOUNTRY AND SOUTHEAST GEORGIA THROUGH
8PM EDT THIS EVENING. SOME AFTERNOON SHOWERS AND THUNDERSTORMS
COULD PROVIDE SOME RELIEF FROM THE HEAT AND POSSIBLY SHORT THE
DURATION OF THE HEAT ADVISORY ACROSS PORTIONS OF THE AREA LATE
THIS AFTERNOON.
MONDAY AND TUESDAY: EXPECT HOT AND HUMID CONDITIONS TO CONTINUE
ACROSS THE REGION AS LARGE-SCALE RIDGING REMAINS IN POSITION
ACROSS THE DEEP SOUTH. THESE LOOK TO BE THE HOTTEST DAYS OF THE
WEEK WITH TEMPERATURES REACHING MID TO UPPER 90S (WITH SOME
SPOTS PEAKING AROUND 100-101F). MIXED IN CONSSHORT AND NBM FOR
THE DEWPOINTS AS THIS SETUP FAVORS STRONG MIXING ACROSS THE
INLAND AREAS AND PORTIONS EAST OF I-95 AS THE SEABREEZE REMAINS
SOMEWHAT PINNED NEAR THE COASTLINE IN THE EARLY AFTERNOON. THIS
WILL LEAD TO SOME UNCERTAINTY WITH THE MAXIMUM HEAT INDEX VALUES
AND DURATION OF PEAK HEATING HOURS MONDAY AND TUESDAY. AN
EXTREME HEAT WARNING HAS BEEN ISSUED FOR THE COASTAL COUNTIES
(INCLUDING INLAND BERKELEY) WITH A HEAT ADVISORY ACROSS THE
REMAINING INLAND COUNTIES ON MONDAY FROM 11AM TO 8PM EDT. WE
WILL LIKELY NEED ADDITIONAL HEAT HEADLINES ON TUESDAY AS WELL.
WEDNESDAY AND THURSDAY: THIS AFOREMENTIONED RIDGE WILL START TO
WEAKEN BY THE MID-WEEK AND SUMMERTIME AFTERNOON CONVECTION
SHOULD MAKE A REAPPEARANCE. THIS PATTERN WILL LIKELY STILL FAVOR
HEAT ADVISORY CONDITIONS PRIOR TO SHOWER AND THUNDERSTORM
DEVELOPMENT (ESP. ACROSS THE COASTAL COUNTIES) ON WEDNESDAY AND
THURSDAY.
KEY MESSAGE 2: A FEW ISOLATED STRONG TO SEVERE THUNDERSTORMS
ARE POSSIBLE THIS AFTERNOON.
THE HEAT AND HUMIDITY DISCUSSED IN KEY MESSAGE 1 WILL ALSO
RESULT IN MODERATE INSTABILITY (SBCAPE 2500-3000+ J/KG) BUILDING
ACROSS THE REGION THIS AFTERNOON. HOWEVER, WITH THE SUBSIDENCE
FROM THE UPPER LEVEL RIDGE, AND THE LACK OF FLOW ALOFT LEADING
TO RATHER LOW 0-6KM SHEAR, PULSE SHOWERS AND THUNDERSTORMS
RATHER THAN ORGANIZED CONVECTION ARE EXPECTED. WILL LIKELY NEED
TO WAIT ON THE EXPECTED AFTERNOON SEA-BREEZE TO GET THE INITIAL
ROUND GOING, WITH ADDITIONAL DEVELOPMENT POSSIBLE ON OUTFLOW AND
BOUNDARY INTERACTIONS. GIVEN THE VERY WARM ENVIRONMENT AND
EXPECTED PULSE-LIKE NATURE, HAIL SEEMS UNLIKELY. HOWEVER, WITH
DCAPE VALUES OF 700-1000 J/KG AND DECENT LOW- LEVEL LAPSE RATES
OF 7-8 DEG C/KM, A FEW ISOLATED STRONG TO SEVERE THUNDERSTORM
GUSTS CANNOT BE RULED OUT. THE 12Z CHS SOUNDING REVEALED A PWAT
OF 2.5 INCHES, WHICH LOOKS TO BE A NEW DAILY MAX, AND WITH
2.2-2.5" PWATS SPREAD OVER THE REST OF THE REGION LOCALLY HEAVY
RAINFALL MAY ALSO OCCUR GIVEN THE WEAK STEERING FLOW. CHANCES
FOR SHOWERS AND THUNDERSTORMS WANE INTO THE EVENING HOURS.
AVIATION /18Z SUNDAY THROUGH FRIDAY/
16/18Z TAFS: SHOWERS AND THUNDERSTORMS HAVE BEGUN INITIATING
NEAR KSAV. THUS, A TEMPO WAS ADDED AT KSAV FOR 18-19Z. A PROB30
GROUP HAS BEEN MAINTAINED AT KCHS/KJZI/KSAV TERMINALS FROM
20-24Z FOR THUNDERSTORMS AND MVFR CONDITIONS. BY 02Z, VFR
CONDITIONS SHOULD RETURN AND PERSIST THROUGH 18Z MONDAY.
EXTENDED AVIATION OUTLOOK: PERIODIC FLIGHT RESTRICTIONS ARE
EXPECTED DUE TO AFTERNOON SHOWERS AND THUNDERSTORMS TUESDAY
THROUGH THURSDAY.
MARINE
REST OF TODAY INTO TONIGHT: CONDITIONS ARE EXPECTED TO REMAIN
QUIET ACROSS LOCAL WATERS BETWEEN THE WESTERN PERIPHERY OF AN
ATLANTIC HIGH AND WEAK TROUGHING INLAND, ALTHOUGH THUNDERSTORMS
THAT DEVELOP OVER LAND THIS AFTERNOON COULD SHIFT OFFSHORE INTO
THE EARLY EVENING HOURS AND PRODUCE GUSTY WINDS. OUTSIDE OF
THUNDERSTORM ACTIVITY, SOUTHERLY WINDS WITH GUST UP TO 10-15 KT
THIS AFTERNOON AND PERSISTING INTO THE EVENING, BEFORE SLOWLY
WEAKENING AND RETURNING TO WEST/SOUTHWEST OVERNIGHT. SEAS SHOULD
BE NO LARGER THAN 2-3 FT.
EXTENDED MARINE: THERE WILL BE AREAS OF HIGH PRESSURE IN THE
WESTERN ATLANTIC AND THE NORTHERN GULF, WHILE SURFACE TROUGHING
WILL PERSIST OVER THE SOUTHEAST U.S. THE INTERACTION BETWEEN ALL
OF THESE SYNOPTIC FEATURES WILL GENERATE A TYPICAL SUMMERTIME
WIND PATTERN. WINDS WILL GENERALLY BE FROM THE SW, BACKING A BIT
EACH DAY AND VEERING SOME EACH NIGHT. THE STRONGEST WINDS
SHOULD BE DURING THE DAY, ESPECIALLY CLOSER TO THE COAST DUE TO
THE SEA BREEZE. SEAS WILL MAINLY BE IN THE 2-3 FT RANGE.
CLIMATE
RECORD HIGH TEMPERATURES:
AUGUST 16:
KCXM: 97/1954
KSAV: 100/1954
AUGUST 17:
KCHS: 102/1954
KSAV: 102/1954
AUGUST 18:
KCHS: 101/1995
KCXM: 97/1995
KSAV: 100/1995
AUGUST 19:
KCHS: 98/1983
KCXM: 98/1895
KSAV: 99/1900
AUGUST 20:
KCHS: 97/2005
RECORD HIGH MINIMUM TEMPERATURES:
AUGUST 16:
KCHS: 78/2019
KSAV: 78/2019
AUGUST 17:
KCHS: 80/2017
KSAV: 78/2017
AUGUST 18:
KCHS: 80/2017
KCXM: 82/2017
KSAV: 78/2010
AUGUST 19:
KCHS: 79/2010
KCXM: 83/2021
KSAV: 79/1878
AUGUST 20:
KCHS: 78/2017
KCXM: 82/2017
AUGUST 21:
KCHS: 79/2010
KCXM: 82/2023
KSAV: 80/1902
AUGUST 22:
KCHS: 79/2023
CHS WATCHES/WARNINGS/ADVISORIES
GA...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR GAZ087-088-
099>101-114-115-137-216>219-238>241.
HEAT ADVISORY FROM 11 AM TO 8 PM EDT MONDAY FOR GAZ087-088-
099>101-114-115-137-216-218-238.
EXTREME HEAT WARNING FROM 11 AM TO 8 PM EDT MONDAY FOR GAZ217-
219-239>241.
SC...HEAT ADVISORY UNTIL 8 PM EDT THIS EVENING FOR SCZ040-042>045-
147>152.
HEAT ADVISORY FROM 11 AM TO 8 PM EDT MONDAY FOR SCZ040-042>044-
147.
EXTREME HEAT WARNING FROM 11 AM TO 8 PM EDT MONDAY FOR SCZ045-
148>152.
MARINE...NONE.
APT/DENNIS
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