020
FXUS62 KCHS 191139
AFDCHS
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE CHARLESTON SC
739 AM EDT WED AUG 19 2026
WHAT HAS CHANGED
THE AVIATION SECTION HAS BEEN UPDATED FOR THE 12Z TAF ISSUANCE.
KEY MESSAGES
- 1) HEAT WILL REMAIN A CONCERN INTO LATE WEEK.
- 2) AFTERNOON AND EVENING THUNDERSTORM COVERAGE WILL REMAIN
ISOLATED THROUGH THURSDAY. AN INCREASE IN THUNDERSTORM
COVERAGE IS EXPECTED FRIDAY THROUGH THE WEEKEND.
DISCUSSION
KEY MESSAGE 1: HEAT WILL REMAIN A CONCERN INTO LATE WEEK.
TODAY: A WARM PATTERN REMAINS IN PLACE WITH LARGE-SCALE RIDGING
EXTENDING ACROSS MUCH OF THE DEEP SOUTH AND SOUTHEAST UNITED STATES.
HOWEVER, WE SHOULD SEE THE FIRST SIGNS OF RIDGE WEAKENING AS A LARGE-
SCALE TROUGH BECOMES POSITIONED ACROSS THE GREAT LAKES REGION. A
WEST FLOW WILL LIMIT OVERALL CONVECTIVE COVERAGE DURING PEAK HEATING
HOURS AND AREAS WELL INLAND ARE EXPECTED TO SEE SFC DEWPTS MIX OUT
SUBSTANTIALLY, INTO THE UPPER 60S WEST OF I-95, THEREFORE LIMITING
THE OVERALL MAXIMUM HEAT INDEX POTENTIAL. HOWEVER, COASTAL ZONES AND
ACROSS PARTS OF BERKELEY COUNTY SHOULD SEE SFC DEWPTS REMAIN IN THE
MID-UPPER 70S, ESPECIALLY WITH MOISTURE POOLING AND/OR AN ONSHORE
WIND ASSOCIATED WITH A SEA BREEZE CIRCULATION. THESE ZONES ARE
EXPECTED TO EXPERIENCE THE HIGHEST HEAT/HUMIDITY COMBINATION AS SFC
TEMPS WARM INTO THE MID-UPPER 90S, PROMPTING A HEAT ADVISORY FROM 11
AM TO 8 PM TODAY. RECORD TEMPS ARE ALSO POSSIBLE (SEE CLIMATE
SECTION BELOW).
THURSDAY AND FRIDAY: THE EXPANSIVE RIDGE THAT HAS PERSISTED ACROSS
THE REGION FOR THE LAST WEEK IS EXPECTED TO WEAKEN LATE WEEK WITH
THE APPROACH OF A LARGE-SCALE TROUGH THIS WEEKEND. UNTIL THE
ANTICIPATED CHANGE, WE COULD SEE HEAT ADVISORY CONDITIONS PRIOR TO
SCATTERED SHOWERS/THUNDERSTORMS DEVELOPING THURSDAY AFTERNOON,
ESPECIALLY ALONG THE COASTAL CORRIDOR WHERE AFTERNOON HIGHS REACH
THE UPPER 90S AND SFC DEWPTS REMAIN IN THE MID-UPPER 70S. LOCATIONS
INLAND SHOULD EXPERIENCE ANOTHER DAY OF STRONG MIXING OUT OF SFC
DEWPTS INTO THE UPPER 60S WEST OF I-95. FRIDAY REMAINS WARM AS WELL,
BUT CONVECTIVE COVERAGE COULD BECOME MORE SUBSTANTIAL AS SHORTWAVE
ENERGY ASSOCIATED WITH A LARGE-SCALE TROUGH APPROACHES THE MID-
ATLANTIC AND SOUTHEAST STATES THIS WEEKEND. TRENDS SUGGEST AFTERNOON
HIGHS TO REMAIN A FEW DEGREES "COOLER" THAN THE PREVIOUS DAY GIVEN
INCREASING CHANCES OF PRECIPITATION, LIMITING HEAT ADVISORY
POTENTIAL ACROSS INLAND AREAS. HOWEVER, SHOULD CONVECTIVE ACTIVITY
REMAIN LESS THAN EXPECTED AND/OR DELAYED UNTIL LATE DAY, THERE
REMAINS A RISK FOR HEAT ADVISORY CONDITIONS ACROSS THE COASTAL
CORRIDOR ON FRIDAY.
KEY MESSAGE 2: AFTERNOON AND EVENING THUNDERSTORM COVERAGE WILL
REMAIN ISOLATED THROUGH THURSDAY. AN INCREASE IN THUNDERSTORM
COVERAGE IS EXPECTED FRIDAY THROUGH THE WEEKEND.
TODAY AND THURSDAY: THE ABOVE NORMAL TEMPERATURES AND STIFLING
HUMIDITY WILL CONTINUE TO GENERATE INSTABILITY THIS AFTERNOON AND
AGAIN THURSDAY AFTERNOON. HOWEVER, MODELS INDICATE CONVECTIVE
COVERAGE SHOULD REMAIN ISOLATED BOTH AFTERNOONS. ANY CONVECTION IS
MOST LIKELY TO FORM ALONG THE SEA BREEZE AND THEN SHIFT INLAND,
DRIVEN BY OUTFLOW AND BOUNDARY INTERACTIONS. STRONG TO SEVERE
THUNDERSTORMS ARE POSSIBLE EACH AFTERNOON WITH THE MAIN THREAT BEING
DAMAGING WINDS. HEAVY RAINFALL IS ALSO A CONCERN DUE TO THE VERY
WEAK STEERING WINDS AND ELEVATED PWATS. ANY CONVECTION WILL DECREASE
BOTH EVENINGS.
FRIDAY INTO THE WEEKEND: THE PATTERN TURNS MORE ACTIVE AS A SLOW
MOVING FRONT APPROACHES OUR AREA FROM THE WEST AND NORTHWEST. THIS
SHOULD GENERATE SCATTERED TO WIDESPREAD THUNDERSTORMS STARTING
FRIDAY AFTERNOON, CONTINUING EACH AFTERNOON THROUGH THE WEEKEND.
EVEN THOUGH THE HEAT WON'T BE AS EXTREME FRIDAY INTO THE WEEKEND,
TEMPERATURES WILL REMAIN ABOVE NORMAL. SBCAPE VALUES COULD STILL GET
QUITE ELEVATED, ALONG WITH DCAPE VALUES. STRONG TO SEVERE
THUNDERSTORMS ARE POSSIBLE EACH AFTERNOON WITH THE MAIN THREAT BEING
DAMAGING WINDS. HEAVY RAINFALL WILL ALSO BE A BIGGER CONCERN DUE TO
THE VERY WEAK STEERING WINDS AND ELEVATED PWATS. FLASH FLOODING IS
POSSIBLE AND THIS HAS BEEN HIGHLIGHTED IN WPC'S ERO.
AVIATION /12Z WEDNESDAY THROUGH SUNDAY/
VFR CONDITIONS ARE EXPECTED AT CHS/JZI/SAV TERMINALS THROUGH 12Z
THURSDAY. HOWEVER, AN ISOLATED SHOWER OR THUNDERSTORM CAN NOT
BE RULED OUT AT THE CHS TERMINAL LATE DAY. THERE ARE ALSO SOME
SIGNS OF REDUCED VSBYS AT CHS/JZI LATE IN THE TAF PERIOD. CONFIDENCE
REMAINS TOO LOW TO INCLUDE MVFR CONDITIONS IN THE LATEST TAF ISSUANCE.
EXTENDED AVIATION OUTLOOK: VFR THROUGH THURSDAY. AFTERNOON SHOWERS
AND THUNDERSTORMS COULD BRING BRIEF FLIGHT RESTRICTIONS STARTING
FRIDAY.
MARINE
TODAY AND TONIGHT: CONDITIONS ARE EXPECTED TO REMAIN QUIET ACROSS
LOCAL WATERS BETWEEN HIGH PRESSURE ACROSS THE WESTERN ATLANTIC/GULF
AND WEAK TROUGHING INLAND. WEST WINDS 5-10 KT THIS MORNING SHOULD
TURN SOUTH WITH GUSTS UP TO AROUND 15 KT THIS AFTERNOON, STRONGEST
NEAR THE COAST WHERE A SEA BREEZE DEVELOPS. WINDS SHOULD THEN RETURN
TO SOUTHWEST AND WEAKEN TO 5-10 KT DURING THE OVERNIGHT PERIOD. SEAS
SHOULD BE NO LARGER THAN 2-3 FT.
EXTENDED MARINE: A TYPICAL SUMMERTIME WIND PATTERN IS EXPECTED WITH
WINDS/SEAS THAT ARE BELOW SMALL CRAFT ADVISORY LEVELS. EACH DAY
THERE WILL BE SOME BACKING OF THE WINDS. THEY'LL BE THE STRONGEST
ALONG THE LAND/SEA INTERFACE DUE TO THE SEA BREEZE. EACH NIGHT WINDS
WILL VEER A BIT. SEAS WILL MAINLY BE IN THE 2-3 FT RANGE.
CLIMATE
RECORD HIGH TEMPERATURES:
AUGUST 19:
KCHS: 98/1983
KCXM: 98/1895
KSAV: 99/1900
AUGUST 20:
KCHS: 97/2005
KSAV: 102/1900
AUGUST 21:
KCHS: 100/1983
KSAV: 101/1902
RECORD HIGH MINIMUM TEMPERATURES:
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
KCXM: 82/2014
KSAV: 79/1902
AUGUST 23:
KCXM: 81/2019
KSAV: 78/2016
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 SCZ045-148>152.
MARINE...NONE.
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