Severe Weather Outbreak-April 8, 2006

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Adams Run, SC F-1 Tornado (courtesy of Ron Chumney)

Summary

A large outbreak of severe thunderstorms impacted much of southeast South Carolina, southeast Georgia and the adjacent Atlantic coastal waters on April 8, 2006 as a potent storm system moved across the region. Four confirmed tornadoes occurred along the central South Carolina coast during this event. The same storm system had produced a deadly outbreak of tornadoes in the Tennessee Valley the previous day. Numerous instances of large hail and some damaging wind reports were reported across the area during the afternoon, mainly between 100 and 500 PM.

The outbreak was largely driven by well-defined thunderstorm outflow boundaries in a warm and moist air mass coinciding with strong wind fields well ahead of an approaching cold front. The initial boundary was associated with a weakened line of thunderstorms that had moved into parts of central Georgia and upstate South Carolina by dawn on the April 8. These storms had been severe in the pre-dawn hours across parts of north Georgia, producing a few tornadoes. Shortly after noon, this boundary separated an increasingly warm and unstable atmosphere across much of southeast Georgia and southeast South Carolina from a slightly cooler and cloudy region from north central Georgia to the South Carolina midlands. Below is a detailed satellite image of the pre-storm environment at 1240 PM.

Thunderstorms began to fire along this boundary during the early afternoon and quickly became severe across Hampton, Allendale, and Colleton Counties in southern South Carolina between 1 PM and 2 PM. Thunderstorms then continued to develop to the northeast along the boundary and produced large hail across Dorchester and Berkeley Counties between 2 PM and 3 PM. These storms exhibited strong tilted updrafts and weak rotation, which helped to sustain both their strength and longevity. Shortly after 3 PM, southeast Georgia started to see rapidly intensifying thunderstorms, which began to produce large hail in parts of Tattnall, Evans, and Bulloch Counties (see radar image below). These thunderstorms continued to gain strength and went on to produce severe weather (mainly in the form of large hail) in parts of Bryan, Liberty, and Chatham Counties in southeast Georgia. The storms organized further and eventually moved into extreme southern South Carolina, producing even more occurrences of severe weather in both Jasper and Beaufort Counties (see radar image below).

Boundary interactions continued to play a huge role in thunderstorm development on this particular afternoon. Cool thunderstorm outflows rushing east from thunderstorms in Hampton County and south from other storms in Dorchester and Berkeley Counties eventually collided with a strong sea breeze boundary extending from southern Colleton County northeastward bisecting all of Charleston County. A rapidly developing and mammoth severe thunderstorm traveled rapidly northeast along the sea breeze front in Charleston County between 345 PM and 500 PM (see radar image below). Locations in far southern parts of Dorchester and Berkeley Counties also experienced large hail with this thunderstorm cluster. Shallow but intense wind shear along the sea breeze boundary was the impetus for development of 4 confirmed tornadoes with this particular thunderstorm cluster. A public information statement describing each of the tornadoes as well as a map showing their locations can be found below.

PUBLIC INFORMATION STATEMENT...UPDATED
NATIONAL WEATHER SERVICE CHARLESTON SC

...NATIONAL WEATHER SERVICE CONFIRMS FOUR TORNADOES IN THE 
CHARLESTON METRO AREA...

DAMAGE ASSESSMENT TEAMS FROM THE NATIONAL WEATHER SERVICE FORECAST 
OFFICE IN CHARLESTON SOUTH CAROLINA SURVEYED DAMAGE THAT OCCURRED 
FROM A SEVERE SUPERCELL THUNDERSTORM THAT MOVED THROUGH MUCH OF 
CHARLESTON COUNTY AS WELL AS PORTIONS OF SOUTHERN DORCHESTER AND 
SOUTHERN BERKELEY COUNTIES BETWEEN 345 PM AND 515 PM ON SATURDAY...
APRIL 8 2006. LARGE HAIL AND DAMAGING WINDS IMPACTED MANY 
COMMUNITIES THROUGHOUT THE AREA. SOME OF THE MOST SEVERE DAMAGE 
OCCURRED IN THE COMMUNITIES OF ADAMS RUN...WEST ASHLEY...THE NECK 
AREA OF THE CHARLESTON PENINSULA AND ON DANIEL ISLAND. TORNADOES 
HAVE BEEN CONFIRMED TO HAVE TOUCHED DOWN IN EACH OF THESE AREAS.

...ADAMS RUN - TRACK REVIEW...
A LARGE SUPERCELL THUNDERSTORM MOVED INTO THE WESTERN PORTIONS OF 
CHARLESTON COUNTY FROM SOUTHERN COLLETON COUNTY NEAR THE COMMUNITY 
OF JACKSONBORO SHORTLY AFTER 345 PM. THE SUPERCELL MOVED RAPIDLY 
EAST AT 45 MPH INTO THE COMMUNITY OF ADAMS RUN BY 350 PM AND 
PRODUCED A TORNADO. THE TORNADO INITIALLY TOUCHED DOWN IN A LARGE
WOODED AREA BETWEEN WILLTOWN AND PARKERS FERRY ROAD THEN CROSSED
WILLTOWN ROAD NEAR MINNIE HUGHS ELEMENTARY SCHOOL SHORTLY BEFORE 
355 PM. HERE THE TORNADO BLEW DOWN AND SNAPPED POWERLINES AND 
NUMEROUS LARGE TREES INCLUDING SEVERAL LARGE GRAND OAKS. HIGH WINDS 
ASSOCIATED WITH THE TORNADO ALSO PARTIALLY COLLAPSED A HOUSE. THE 
TORNADO CONTINUED TO MOVE EAST-SOUTHEAST AND CROSSED HIGHWAY 174 
JUST NORTH OF THE INTERSECTION WITH MOFFETT ROAD. HERE A LARGE PATCH
OF PINE TREES AS WELL AS SEVERAL LARGE GRAND OAKS WERE SNAPPED AND 
UPROOTED. THE TORNADO THEN MOVED INTO AN OPEN FARM FIELD WHERE IT 
DAMAGED MORE TREES. THE TORNADO FINALLY MOVED ACROSS TOOGOODOO ROAD 
NEAR THE INTERSECTION OF OAKVILLE ROAD WHERE IT DAMAGED SEVERAL HOMES 
BEFORE DISSIPATING ABOUT 2 MILES FARTHER TO THE EAST-SOUTHEAST IN A 
NEARBY MARSHY AREA AROUND TOOGOODOO CREEK.

THE DAMAGE TEAM HAS DETERMINED THAT BASED ON THE SEVERITY OF 
OBSERVED DAMAGE IN THE ADAMS RUN AREA THAT THIS TORNADO REACHED THE 
HIGH END RANGE OF AN F1 TORNADO WITH ESTIMATED WINDS OF 100-110 MPH.

-- TORNADO STATISTICS --
LOCATION...         ADAMS RUN SC
F-SCALE RATING...   F1
ESTIMATED WINDS...  100-110 MPH
TORNADO WIDTH...    200-300 FT
TORNADO LENGTH...   4.5 MILES
INITIAL TOUCHDOWN TIME... 353 PM EDT

...WEST ASHLEY /CITY OF CHARLESTON/ - TRACK REVIEW...
THE SUPERCELL THUNDERSTORM THAT PRODUCED A TORNADO NEAR ADAMS RUN 
REACHED THE WEST ASHLEY AREA OF CHARLESTON AROUND 420 PM AND SPAWNED 
A BRIEF TORNADO IN THE AVENDALE NEIGHBORHOOD AROUND 425 PM. THE 
TORNADO TOUCHED DOWN NEAR THE INTERSECTION OF COBURG ROAD AND 
HIGHWAY 17 /SAVANNAH HIGHWAY/...MOVED QUICKLY ACROSS HIGHWAY 17 AND 
LIFTED NEAR THE INTERSECTION OF HIGHWAY 17 AND MAGNOLIA ROAD. THE 
TORNADO BLEW OUT WINDOWS IN SEVERAL BUSINESSES AND BLEW DOWN SEVERAL 
LARGE TREES. SEVERAL BUSINESSES ALSO SUFFERED MINOR STRUCTURAL 
DAMAGE. SEVERAL PEOPLE WITNESSED THE TORNADO AS IT MOVED ACROSS 
HIGHWAY 17 AND DESCRIBED THE TORNADO AS VERY THIN AND ROPE LIKE.

THE DAMAGE TEAM HAS DETERMINED THAT BASED ON THE SEVERITY OF THE 
OBSERVED DAMAGE IN THE WEST ASHLEY AREA THAT THIS TORNADO LIKELY 
REACHED THE HIGH END RANGE OF AN F0 TORNADO WITH ESTIMATED WINDS OF 
60-70 MPH.

-- TORNADO STATISTICS --
LOCATION...  WEST ASHLEY /CITY OF CHARLESTON/ SC
F-SCALE RATING...   F0
ESTIMATED WINDS...  60-70 MPH
TORNADO WIDTH...    100 FEET
TORNADO LENGTH...   200-300 YARDS
INITIAL TOUCHDOWN TIME... 425 PM EDT

...DANIEL ISLAND /BERKELEY COUNTY/ - TRACK REVIEW...
THE NORTHERN EXTENT OF THE SUPERCELL THUNDERSTORM MOVED ACROSS 
DANIEL ISLAND BETWEEN 420 PM AND 435 PM AND PRODUCED A TORNADO. THE 
TORNADO FORMED BETWEEN 420 AND 425 PM JUST NORTH OF THE ISLAND PARK 
DRIVE/RIVER LANDING DRIVE INTERSECTION. THE TORNADO MOVED EAST AND 
BROKE OUT THE FRONT GLASS DOOR OF A WEST FACING BUSINESS ON ISLAND 
PARK DRIVE. NUMEROUS OTHER WEST FACING GLASS DOORS AND WINDOWS WERE 
NOT IMPACTED. THE TORNADO THEN MAINLY TRAVELED ACROSS A POND AND A 
GRASS COVERED FIELD UPROOTING A COUPLE TREES BEFORE HITTING THE 
FAMILY CIRCLE TENNIS CENTER AND THEN LIFTING. 

AT THE TENNIS CENTER...TWO VERY LARGE BANNERS WERE SEVERELY 
DAMAGED...TWO HEAVY DUTY TENTS WERE TOPPLED...A METAL SUPPORT BEAM 
FROM ONE OF THE TENTS WAS SNAPPED IN TWO AND ONE PANEL OF THE TENNIS 
CENTER SCOREBOARD WAS DAMAGED. TWO LARGE DRUMS FILLED WITH WATER AND 
WEIGHTING ABOUT 300 POUNDS THAT WERE USED TO THE HOLD THE TENTS DOWN 
WERE MOVED ABOUT 12 FEET. IN ADDITION...A TEMPORARY LIGHT DISPLAY 
DAMAGED A VEHICLE WHEN THE TORNADO KNOCKED IT DOWN ONTO A VEHICLE.
 
THE DAMAGE TEAM DETERMINED THAT BASED ON THE OBSERVED DAMAGE THAT 
THIS TORNADO LIKELY REACHED THE UPPER END OF AN F0 TORNADO WITH 
ESTIMATED WINDS OF 60-70 MPH. 

-- TORNADO STATISTICS --
LOCATION...   DANIEL ISLAND /BERKELEY COUNTY/ SC 
F-SCALE RATING...   F0
ESTIMATED WINDS...  60-70 MPH
TORNADO WIDTH...    140 FEET
TORNADO LENGTH...   400 YARDS
INITIAL TOUCHDOWN TIME...423 PM EDT

...CHARLESTON NECK AREA /CITY OF CHARLESTON/- TRACK REVIEW...
THE SAME SUPERCELL THUNDERSTORM THAT PRODUCED TORNADOES IN WEST 
ASHLEY...ADAMS RUN AND DANIEL ISLAND ALSO SPAWNED A WEAK TORNADO IN 
THE NECK AREA OF THE CHARLESTON PENINSULA AROUND 420 PM. THE TORNADO 
INITIALLY TOUCHED DOWN NEAR THE DOLPHIN MARINA AND THE LIQUID 
TRANSPORT CORPORATION ALONG AUSTIN AVENUE...SEVERAL HUNDRED FEET 
FROM THE SHORES OF THE ASHLEY RIVER. HERE SEVERAL TREES WERE BLOWN 
DOWN AND A LARGE 10-15 FOOT DECK WAS TORN AWAY FROM A TAILER AND 
BLOWN ABOUT 30 FEET UP AGAINST A FENCE. THE TORNADO THEN PROCEEDED 
TO CROSS INTERSTATE 26 NEAR THE INTERSECTION OF AUSTIN AVENUE AND 
SUMMERVILLE ROAD AND CROSSED MEETING STREET NEAR THE INTERSECTION OF 
PITTSBURGH AVENUE. HERE SEVERAL TREES INCLUDING A LARGE GRAND OAK 
WERE TWISTED AND SNAPPED. THE KANGAROO GAS STATION ALSO EXPERIENCED 
MINOR DAMAGE. THE TORNADO THEN MOVED ACROSS A LARGE CONSTRUCTION 
SITE NEAR THE END OF PITTSBURGH AVENUE AND CROSSED SHIPYARD CREEK. 
INTERVIEWS WITH SEVERAL WORKERS AT THE CONSTRUCTION SITE SAID 
VISIBILITIES DROPPED TO ZERO AS THE TORNADO PICKED UP A CONSIDERABLE 
AMOUNT OF DIRT LOCATED ON THE PREMISES. PENNY SIZE HAIL ALSO 
OCCURRED AFTER THE TORNADO PASSED. THE TORNADO FINALLY MOVED ACROSS 
THE COOPER RIVER MARINA...LOCATED ON THE EXTREME SOUTHERN PORTIONS 
OF THE CHARLESTON NAVY BASE...AND DISSIPATED OVER THE EXTREME 
SOUTHERN PORTIONS OF DANIEL ISLAND ONCE IT CROSSED THE COOPER RIVER. 
THE COOPER RIVER MARINA ASSISTANT MANAGER REPORTED THE TORNADO WAS 
ACCOMPANIED BY A LARGE AMOUNT OF DIRT...A LOUD ROARING SOUND AND 
PENNY SIZE HAIL. HIGH WINDS ASSOCIATED WITH THE TORNADO BLEW SEVERAL 
LARGE PICNIC TABLES ABOUT 15-20 FT...BLEW LARGE DOCK CONTAINERS 
/WEIGHTING 50-100 LBS/ INTO THE WATER AND DESTROYED THE MARINA/S 
WIND OBSERVING EQUIPMENT. THE WIND EQUIPMENT MEASURED SUSTAINED 
WINDS OF 47 MPH BEFORE IT WAS DESTROYED. SEVERAL TREES WERE ALSO 
SNAPPED ON THE FAR SOUTHWESTERN SHORES OF DANIEL ISLAND BEFORE THE 
TORNADO DISSIPATED.

-- TORNADO STATISTICS --
LOCATION... CHARLESTON SC 
F-SCALE RATING...   F0
ESTIMATED WINDS...  60-70 MPH
TORNADO WIDTH...    130 FEET
TORNADO LENGTH...   2.5 MILES
INITIAL TOUCHDOWN TIME...420 PM EDT

THE NATIONAL WEATHER SERVICE IN CHARLESTON WISHES TO THANK THE 
CITIZENS OF CHARLESTON AND BERKELEY COUNTIES...THE CHARLESTON 
BROADCAST AND PRINT MEDIA...LOCAL EMERGENCY MANAGEMENT OFFICIALS... 
AND THE FAMILY CIRCLE TENNIS CENTER FOR THEIR ASSISTANCE.

AN EVENT SUMMARY INCLUDING PICTURES OF THE TORNADOES...TRACK MAPS 
AND DAMAGE PHOTOS...WILL BE POSTED ON THE NATIONAL WEATHER SERVICE 
IN CHARLESTON/S WEBSITE NEXT WEEK.

THE NATIONAL WEATHER SERVICE IS STILL LOOKING FOR ADDITIONAL 
REPORTS. IF YOU EXPERIENCED HAIL...DAMAGING WINDS OR OBSERVED A 
TORNADO LAST SATURDAY...THE NATIONAL WEATHER SERVICE IN CHARLESTON 
WOULD LIKE TO HEAR FROM YOU. PLEASE CALL US TOLL FREE AT 1-888- 
383-2024 AND LEAVE A MESSAGE OR YOU CAN EMAIL YOUR REPORTS AND 
PICTURES TO CHS.SKYWARN@NOAA.GOV. THANK YOU.