With a weak and broad trough positioned aloft and a weak trough at the surface, thunderstorms developed in afternoon heating.
Every event with a place to put it. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS CHS wrote it up.
With a weak and broad trough positioned aloft and a weak trough at the surface, thunderstorms developed in afternoon heating.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS Charleston, SC wrote its last area forecast discussion before the first event at Aug 23, 12:00 PM EST, 30 minutes earlier.
AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC ISSUED BY NATIONAL WEATHER SERVICE COLUMBIA SC 100 PM EDT THU AUG 23 2012 .SYNOPSIS... A WEAK PRESSURE PATTERN WILL CONTINUE ACROSS THE REGION THROUGH TONIGHT. HIGH PRESSURE WILL BUILD IN FROM THE NORTHEAST ON FRIDAY AND REMAIN IN PLACE THROUGH THE WEEKEND. THE HIGH WILL THEN BEGIN TO WEAKEN EARLY NEXT WEEK AS TROPICAL CYCLONE ISAAC MOVES TOWARD FLORIDA AND THE EASTERN GULF OF MEXICO. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE MID/UPPER TROUGH AXIS TO REMAIN JUST WEST OF THE AREA TODAY WHILE THE STALLED SURFACE FRONT MOVES LITTLE. HIGHEST CONVERGENCE FROM UVALDA TO HILTON HEAD ISLAND. ATMOSPHERE MODERATELY UNSTABLE WITH CAPES 2000 TO 2500 J/KG AND LIFTED INDICES DOWN TO MINUS 6. HAVE INCREASED POPS TO LIKELY SOUTH...AND KEPT 50 PERCENT NORTH TO AROUND 30 PERCENT FARTHER INLAND WHERE PRECIPITABLE WATER IS LOWER. HEAVY RAIN POSSIBLE. HIGHS MAINLY IN THE MID 80S STILL LOOK GOOD GIVEN CLOUD COVER. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... STRONGER MID LEVEL VORTICITY MAX FORECAST TO SHIFT NE OF OUR SOUTH CAROLINA REGION TONIGHT BUT WEAK SECONDARY SHORT WAVES STILL IN THE PICTURE. IT LOOKS LIKE A SCENARIO SIMILAR TO PAST DAYS AS EVENING SHOWER AND ISOLATED TSTM COVERAGE DECREASES DURING THE EVENING AND ESPECIALLY POST-SUNSET. OVERNIGHT LOW LEVEL CONVERGENCE GATHERS NEAR THE IMMEDIATE COAST AND SHOWERS REDEVELOP AFTER 2 AM. GIVEN THE SYNOPTIC SETUP...WE HAVE BUMPED LATE NIGHT POPS ALONG THE CHARLESTON TRI-COUNTY TO CHANCE RANGES. MUCH OF SE GEORGIA SHOULD BE DRY OVERNIGHT WITH SOME BREAKS IN THE CLOUDS AT TIMES. LOWS IN THE UPPER 60S TO LOWER 70S. FRIDAY AND FRIDAY NIGHT...THE BAGGY MID/UPPER LEVEL TROF WILL CONTINUE TO LINGER AROUND THE SOUTHEAST WITH A WEAK UPPER LOW DEVELOPING OVER VIRGINIA AND THE CAROLINAS. HIGH PRESSURE AT THE SURFACE WILL STEADILY BUILD IN FROM THE NORTHEAST THROUGH THE DAY AS THE DEEPER MOISTURE BEGINS TO RETREAT TO THE NORTHEAST. MODELS DEPICT A WEAK SURFACE WAVE ASSOCIATED WITH THE UPPER TROF/LOW LOCATED OVER THE ATLANTIC JUST TO THE EAST OF THE TRI-COUNTY REGION. WITH THE BETTER MOISTURE FAVORING AREAS FURTHER TO THE NORTHEAST CLOSER TO THE TROF...THE EXPECTATION IS FOR THE BETTER COVERAGE OF SHOWERS/THUNDERSTORMS TO BE IN THIS AREA. I HAVE GENERALLY KEPT THE POP DISTRIBUTION AS IT WAS...WITH A BIT OF TAPERING OVER SE GA TO JUST SLIGHT CHANCE. TEMPS WILL BE IN THE MID TO UPPER 80S...STILL A DEGREE OR TWO BELOW CLIMO. OVERNIGHT...ANY LINGERING CONVECTION WILL DIE OFF QUICKLY AFTER SUNSET WITH JUST A SLIGHT CHANCE OFFSHORE CLOSER TO THE GULF STREAM WITHIN A SUBTLE DEVELOPING COASTAL TROF. SATURDAY THROUGH SUNDAY...OVERALL THE PATTERN WILL CHANGE VERY LITTLE. THE WEAK CLOSED LOW/UPPER TROF WILL MEANDER TOWARD THE MID ATLANTIC STATES AS THE REGION GETS CAUGHT UP IN THE BROADER WEST TO EAST ORIENTED UPPER RIDGE. HIGH PRESSURE WILL REMAIN THE DOMINANT SURFACE FEATURE WITH A VERY WEAK COASTAL TROF POSSIBLE JUST OFFSHORE. RAIN CHANCES WILL LARGELY BE DRIVEN BY SURFACE HEATING AND CONVERGENCE WITHIN THE COASTAL TROF AND AFTERNOON SEA BREEZE...BUT THE DRIER AIR AND LACK OF ANY UPPER SUPPORT WILL KEEP RAIN CHANCES LOW. THE MODELS GENERALLY HAVE MEAGER PRECIP RESPONSE EACH AFTERNOON AND POPS MAX OUT IN THE SLIGHT CHANCE RANGE. TEMPS WILL REMAIN A COUPLE OF DEGREES BELOW CLIMO AS A COOLER NE FLOW DOMINATES. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS EXPECTED...THE MAJORITY OF THE LONG TERM FORECAST PERIOD CONTINUES TO REVOLVE AROUND TROPICAL CYCLONE ISAAC AND ITS EVENTUAL TRACK. OVERALL...GUIDANCE HAS COME A BIT MORE IN LINE REGARDING THE GENERAL PATH OF ISAAC TAKING IT INTO THE FAR EASTERN GULF OF MEXICO MONDAY NIGHT AND TUESDAY. THEREAFTER THE TRACK APPEARS TO TAKE ON A MORE NORTHERLY COMPONENT APPROACHING SOME PORTION OF THE CENTRAL TO EASTERN GULF COAST. FORECAST CONFIDENCE IN THE POTENTIAL IMPACTS FROM THE SYSTEM ON THE FORECAST AREA REMAINS QUITE LOW...AND WILL BE DEPENDENT ON ITS TRACK AND INTENSITY. CONTINUE TO MONITOR NHC ADVISORIES ON ISAAC FOR THE LATEST FORECAST INFORMATION. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... VFR OUTSIDE OF SCATTERED TO NUMEROUS TSTMS. STORMS MAINLY AFFECTING KSAV EARLY THIS AFTERNOON...BUT SHOULD DEVELOP IN THE KCHS VCNTY LATER THIS AFTERNOON. MUCH OF THE CONVECTION EXPECTED TO DIMINISH THIS EVENING. PATCHY LOW CLOUDS AND FOG POSSIBLE LATE TONIGHT. EXTENDED AVIATION OUTLOOK...PRIMARILY VFR. ISOLATED TO SCATTERED SHOWERS/THUNDERSTORMS COULD BRING BRIEF CEILING AND VISIBILITY REDUCTIONS...MAINLY IN THE AFTERNOON AND EVENING. && .MARINE... LIGHT AND OCCASIONALLY VARIABLE LOW LEVEL WIND FIELDS AND AMPLE MOISTURE AND INSTABILITY SUGGEST A POTENTIAL FOR WATERSPOUTS INTO EARLY AFTERNOON. OTHERWISE...A WEAK FRONT IS LINGERING OVER THE WATERS THROUGH TONIGHT WITH LIGHT WINDS AND SEAS AT OR BELOW 2 FT. FRIDAY THROUGH MONDAY...HIGH PRESSURE WILL BUILD IN ACROSS INLAND AREAS THROUGH THE WEEKEND LEADING TO A PERSISTENT NE FLOW REGIME ACROSS THE WATERS INTO EARLY NEXT WEEK. MODELS DO SHOW THE PRESSURE GRADIENT TIGHTENING UP DURING THIS TIME AND A CORRESPONDING INCREASE IN FLOW IS EXPECTED ESPECIALLY BY SATURDAY NIGHT AND SUNDAY. THE FLOW MAY STRENGTHEN FURTHER BY MONDAY AS THE PRESSURE GRADIENT TIGHTENS NORTH OF TROPICAL CYCLONE ISAAC NEAR SOUTH FLORIDA. CONDITIONS ARE EXPECTED TO REMAIN BELOW SMALL CRAFT ADVISORY CRITERIA THROUGH AT LEAST THE WEEKEND...BEFORE POSSIBLY BECOMING MORE MARGINAL SUPPORTIVE FOR THE GEORGIA WATERS BY MONDAY. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...NONE. &&
HAZARDOUS WEATHER OUTLOOK NATIONAL WEATHER SERVICE CHARLESTON SC 514 AM EDT THU AUG 23 2012 AMZ330-350-352-354-374-GAZ087-088-099>101-114>119-137>141-SCZ040- 042>045-047>052-240915- CHARLESTON HARBOR- WATERS FROM SOUTH SANTEE RIVER TO EDISTO BEACH SC OUT 20 NM- WATERS FROM EDISTO BEACH SC TO SAVANNAH GA OUT 20 NM- WATERS FROM SAVANNAH GA TO ALTAMAHA SOUND GA OUT 20 NM...INCLUDING GRAYS REEF NATIONAL MARINE SANCTUARY- WATERS FROM SAVANNAH GA TO ALTAMAHA SOUND GA EXTENDING FROM 20 TO 60 NM-JENKINS-SCREVEN-CANDLER-BULLOCH-EFFINGHAM-TATTNALL-EVANS- INLAND BRYAN-COASTAL BRYAN-INLAND CHATHAM-COASTAL CHATHAM-LONG- INLAND LIBERTY-COASTAL LIBERTY-INLAND MCINTOSH-COASTAL MCINTOSH- ALLENDALE-HAMPTON-INLAND COLLETON-DORCHESTER-INLAND BERKELEY- INLAND JASPER-BEAUFORT-COASTAL COLLETON-CHARLESTON-COASTAL JASPER- TIDAL BERKELEY- 514 AM EDT THU AUG 23 2012 THIS HAZARDOUS WEATHER OUTLOOK IS FOR ATLANTIC COASTAL WATERS...SOUTHEAST GEORGIA AND SOUTHEAST SOUTH CAROLINA. .DAY ONE...TODAY AND TONIGHT. WATERSPOUTS...LIGHT AND VARIABLE WINDS ALONG WITH MOIST AND UNSTABLE CONDITIONS ACROSS THE INTRACOASTAL AND NEAR SHORE COASTAL WATERS MAY LEAD TO AN ENHANCED RISK FOR WATERSPOUTS THROUGH THE MORNING HOURS. .DAYS TWO THROUGH SEVEN...FRIDAY THROUGH WEDNESDAY. TROPICAL WEATHER...IMPACTS ASSOCIATED WITH TROPICAL CYCLONE ISAAC WILL BE POSSIBLE BEGINNING IN THE EARLY TO MIDDLE PART OF NEXT WEEK. FOR THE LATEST OFFICIAL FORECAST INFORMATION...REFER TO ADVISORIES ISSUED BY THE NATIONAL HURRICANE CENTER. .SPOTTER INFORMATION STATEMENT... SPOTTER ASSISTANCE IS NOT ANTICIPATED AT THIS TIME.
SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE CHARLESTON SC
ISSUED BY NATIONAL WEATHER SERVICE COLUMBIA SC
1233 PM EDT THU AUG 23 2012
GAZ117>119-SCZ051-231730-
COASTAL BRYAN-COASTAL CHATHAM-COASTAL JASPER-INLAND CHATHAM-
1233 PM EDT THU AUG 23 2012
...STRONG THUNDERSTORMS WILL IMPACT PORTIONS OF BRYAN...JASPER AND
CHATHAM COUNTIES THROUGH 130 PM EDT...
AT 1230 PM EDT...NATIONAL WEATHER SERVICE DOPPLER RADAR INDICATED A
STRONG THUNDERSTORM...NEAR PARKERSBURG. THIS STORM IS NEARLY
STATIONARY AND HAS POTENTIAL TO PRODUCE LOCALLY HEAVY RAIN. RAINFALL
AMOUNTS UP TO 3.00 INCHES IS POSSIBLE WITH THIS STORM.
SOME LOCATIONS THAT WILL BE AFFECTED INCLUDE...
BURROUGHS...FORT MCALLISTER...ISLE OF HOPE...RIVERSIDE...SANDFLY...
SAVANNAH...SKIDAWAY ISLAND...THUNDERBOLT...TYBEE ISLAND...
VERNONBURG...WHITE BLUFF...WILMINGTON ISLAND AND WINDSOR FOREST...
PREPARE NOW FOR THE FOLLOWING HAZARDS...
GUSTY WINDS OF 30 TO 40 MPH...
TORRENTIAL RAIN WHICH MAY PRODUCE LOCALIZED FLOODING...
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REPORT LARGE HAIL...DAMAGING WINDS OR FLOODING TO YOUR COUNTY
SHERIFF...OR CALL THE NATIONAL WEATHER SERVICE TOLL FREE AT 1...8 7
7...6 3 3...6 7 7 2.
&&
LAT...LON 3175 8109 3184 8123 3191 8122 3189 8123
3189 8124 3196 8129 3213 8111 3212 8113
3209 8109 3209 8108 3211 8111 3210 8108
3219 8105 3207 8088 3205 8089 3203 8087
3203 8084 3201 8083
TIME...MOT...LOC 1631Z 271DEG 3KT 3199 8104
AWPThe Charleston,SC radar (KCLX), 58 km away, was scanning. The volume nearest the first event began at 17:28 UTC.
1 thunderstorm wind. Local standard time, as filed.
A trained spotter reported power lines blown down near the entrance to the Georgia port. The spotter also observed pea sized hail.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in Georgia in 2012Every state in 2012This day in weather historyWarnings in Georgia, August 2012
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 410711.