Thunderstorms developed south of a warm front and ahead of a cold front in an environment characterized by high shear, low Lifted Condensation Levels (LCLs), and low levels of instability, which is favorable for tornadoes. In fact, NWS Charleston confirmed four tornadoes; one in Chatham County, GA, two in Colleton County, SC and one in Colleton and Dorchester Counties in SC. The image below shows the Multi-Radar Multi-Sensor (MRMS) low-level rotational tracks indicating the track of the strongest low-level rotations, including from the supercell that produced the tornadoes from Chatham County, GA northward into Dorchester County, SC.
Graphics
Click on images to enlarge
Top-Left: NWS Storm Prediction Center (SPC) Day One Convective Outlook (issued May 4 @ 103 AM EDT) and storm reports
Top-Right: NWS Weather Prediction Center (WPC) surface analysis at 5 pm EDT on May 4
Bottom-Left: NWS SPC 500-mb analysis at 8 pm EDT on May 4
Bottom-Right: NWS SPC analysis of Effective Significant Tornado Parameter at 5 pm EDT on May 4
Click on images to enlarge
Chatham County, GA (Garden City) | ||
KCLX Base (0.5 Degree) Reflectivity (May 4, 2017 - 550 PM EDT) |
KCLX Base (0.5 Degree) Storm-relative Velocity (May 4, 2017 - 550 PM EDT) |
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Colleton County, SC (near Hendersonville) | ||
KCLX Base (0.5 Degree) Reflectivity (May 4, 2017 - 744 PM EDT) |
KCLX Base (0.5 Degree) Storm-relative Velocity (May 4, 2017 - 744 PM EDT) |
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Colleton County, SC (near Walterboro) | ||
KCLX Base (0.5 Degree) Reflectivity (May 4, 2017 - 816 PM EDT) |
KCLX Base (0.5 Degree) Storm-relative Velocity (May 4, 2017 - 816 PM EDT) |
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Colleton/Dorchester Counties, SC (near Canadys) | ||
KCLX Base (0.5 Degree) Reflectivity (May 4, 2017 - 825 PM EDT) |
KCLX Base (0.5 Degree) Storm-relative Velocity (May 4, 2017 - 825 PM EDT) |
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Images courtesy of NWS Charleston, SC; click to enlarge
Chatham County, GA (Garden City) | ||||
Colleton/Dorchester Counties, SC | ||||
Public Information Statement National Weather Service Charleston SC 518 PM EDT Mon May 8 2017 ...MULTIPLE TORNADOES CONFIRMED ON 05/04/17... ...TORNADO CONFIRMED NEAR HENDERSONVILLE IN COLLETON COUNTY SOUTH CAROLINA... Location...Hendersonville in Colleton County South Carolina Date...May 4 2017 Estimated Time...745 PM EDT Maximum EF-Scale Rating...EF1 Estimated Maximum Wind Speed...110 mph Maximum Path Width...440 yards Path Length...12.56 miles Beginning Lat/Lon...32.7933 N / 80.7796 W Ending lat/Lon...32.9558 N / 80.6811 W * Fatalities...0 * Injuries...0 * The information in this statement is preliminary and subject to change pending final review of the event(s) and publication in NWS Storm Data. ...Summary... The National Weather Service in Charleston SC has confirmed a tornado near Hendersonville in Colleton County South Carolina on May 4, 2017. The tornado initially touched down approximately 1/2 mile southwest of the Hendersonville Rest Area off Interstate 95, with a north/northeast intermittent path of approximately 5.5 miles. Along the path, the tornado crossed State Road S-15-28, snapping several trees. The tornado then continued north-northeast where it caused damage to a house and barn just north of Black Creek Road. Several snapped and uprooted trees along with a few downed power poles also occurred at this location. The tornado then continued north-northeast crossing Magellan Road, where approximately 100 trees were snapped. The tornado then continued north-northeast where it produced tree and home damage along Cane Branch Road. At this point, the tornado path became continuous from the damage along Cane Branch Road until the tornado dissipated along the I-95. Damage to a house on Cane Branch Road included a 6500 pound boat and trailer being displaced about 30 yards from their original position, a golf cart being lifted up and moved about 20 yards, two large branches being driven through the side of the house, several windows being broken out, and significant damage to metal roofing material. In addition, the house was shifted a bit on its foundation. Numerous trees were snapped near the property of this home. The tornado then continued north-northeast toward Sniders Highway (Route 63), where it produced minor roof and siding damage to a mobile home, tossed a trampoline into a tree line about 20 feet off the ground, snapped a few trees and severely damaged/turned an old barn on its side. The tornado then crossed Highway 63, snapping 2 power poles and causing minor roof and siding damage to a 2 story house. The tornado continued north crossing Donald Court Point, where a mobile home was seen leaning on cinder blocks along with skirting destroyed. Two adjacent mobile homes also received minor skirt damage. The tornado then continued north, gaining strength and width while approaching Walterboro, South Carolina. The maximum tornado strength (EF1) and width (1/4 mile) was surveyed about 1/4 mile west of a large shopping complex along Highway 64, where approximately 1000 trees were either snapped, uprooted and/or severely damaged. The tornado then continued on a north/northeast track damaging dozens of trees while crossing Mount Carmel Road, before lifting approximately 2 miles north of exit 57 on Interstate 95 off of Windmere Lane where damage to trees, power lines and a large billboard occurred. This information can also be found on our website at weather.gov/chs. For reference: the Enhanced Fujita Scale classifies tornadoes into the following categories: EF0...Wind speeds 65 to 85 mph EF1...Wind speeds 86 to 110 mph EF2...Wind speeds 111 to 135 mph EF3...Wind speeds 136 to 165 mph EF4...Wind speeds 166 to 200 mph EF5...Wind speeds greater than 200 mph && ...TORNADO CONFIRMED NEAR WALTERBORO IN COLLETON COUNTY SOUTH CAROLINA... Location...Walterboro in Colleton County South Carolina Date...May 4 2017 Estimated Time...816 PM EDT Maximum EF-Scale Rating...EF1 Estimated Maximum Wind Speed...100 mph Maximum Path Width...125 yards. Path Length...6.02 miles. Beginning Lat/Lon...32.9880 N / 80.6490 W Ending Lat/Lon...33.0571 N / 80.5859 W * Fatalities...0 * Injuries...0 * The information in this statement is preliminary and subject to change pending final review of the event(s) and publication in NWS Storm Data. ...Summary... The National Weather Service in Charleston SC has confirmed a tornado near Walterboro in Colleton County South Carolina on May 4, 2017. The tornado touched town just west of McLeod Road, damaging the roofing and siding of a home on McLeod Road. The tornado then traveled north-northeast producing intermittent damage along the path. The tornado produced extensive tree damage along Allen Creek just to the west of Route 15 where approximately 100 trees were snapped off, uprooted, or severely damaged. The tornado produced fence damage along Route 15 just north of Allen Creek and thereafter produced intermittent tree damaging along the path. The tornado crossed a corn field about 2 miles east of Canadys where a convergent wind pattern was clearly evident. The tornado snapped off, uprooted or damaged numerous trees in this area before dissipating just south of the Edisto River. This information can also be found on our website at weather.gov/chs. For reference: the Enhanced Fujita Scale classifies tornadoes into the following categories: EF0...Wind speeds 65 to 85 mph EF1...Wind speeds 86 to 110 mph EF2...Wind speeds 111 to 135 mph EF3...Wind speeds 136 to 165 mph EF4...Wind speeds 166 to 200 mph EF5...Wind speeds greater than 200 mph && ...TORNADO CONFIRMED NEAR CANADYS IN COLLETON AND DORCHESTER COUNTY SOUTH CAROLINA... Location...Canadys in Colleton and Dorchester County South Carolina Date...May 4 2017 Estimated Time...825 PM EDT Maximum EF-Scale Rating...EF1 Estimated Maximum Wind Speed...100 mph Maximum Path Width...150 yards Path Length...2.02 miles Beginning Lat/Lon...33.0530 N / 80.5850 W Ending Lat/Lon...33.0817 N / 80.5807 * Fatalities...0 * Injuries...0 * The information in this statement is preliminary and subject to change pending final review of the event(s) and publication in NWS Storm Data. ...Summary... The National Weather Service in Charleston SC has confirmed a tornado near Canadys in Colleton and Dorchester Counties South Carolina on May 4, 2017. The tornado developed just southeast of the second tornado likely as the second tornado was dissipating and then traveled north- northeast across the Edisto River and into Dorchester County. This tornado snapped off, uprooted and damaged trees about 2 miles east of Canadys. The damage from this tornado was clearly separate and about 1000 feet east of the second tornado as it approached the Edisto River. The tornado then dissipated along Utsey Hill Road. This information can also be found on our website at weather.gov/chs. For reference: the Enhanced Fujita Scale classifies tornadoes into the following categories: EF0...Wind speeds 65 to 85 mph EF1...Wind speeds 86 to 110 mph EF2...Wind speeds 111 to 135 mph EF3...Wind speeds 136 to 165 mph EF4...Wind speeds 166 to 200 mph EF5...Wind speeds greater than 200 mph $$ Public Information Statement National Weather Service Charleston SC 943 PM EDT Sat May 6 2017 ...HIGH END EF1 TORNADO CONFIRMED NEAR GARDEN CITY IN CHATHAM COUNTY GEORGIA... Location...Garden City in Chatham County Georgia Date...May 4 2017 Estimated Time...550 pm Maximum EF-Scale Rating...EF1 Estimated Maximum Wind Speed...110 MPH Maximum Path Width...120 yards Path Length...2.86 miles Beginning Lat/Lon...32.0805 N / 81.1480 W Ending lat/Lon...32.1178 N / 81.1292 W * Fatalities...0 * Injuries...5 * The information in this statement is preliminary and subject to change pending final review of the event(s) and publication in NWS Storm Data. ...Summary... The National Weather Service in Charleston SC has maintained the high end EF1 rating for the tornado that struck the southern portion of Garden City, GA in Chatham County Georgia on May 4 2017. The tornado began near the intersection of Seaboard Coastline Drive and Telfair Junction roads. At this location, damage was mainly limited to some snapped trees and minor wind damage to the bottom skirts of some mobile office trailers. The tornado continued northward with the next damage area along Alfred Street, just east of Market Street. At this location there were some snapped trees and minor damage to the wall of one home, which was partially blow down, causing the garage door to blow out. From this point, the tornado moved northward producing sporadic, non- continuous damage. About one third of a metal roof of an industrial building just north of Market Street was damaged. Next the tornado moved toward the more industrial and commercial area just south of U.S. 80, where it did significant damage to the Advance Auto Parts store. Three walls collapsed and the roof was heavily damaged and shifted halfway off the remaining rear wall. At this point, the tornado had is strongest winds, estimated to be around 110 mph. The rating was capped at a high end EF1 due to the lack of damage or much less significant damage to structures immediately around the store. There were also five people injured inside the Advance Auto Parts store, and at least 5 cars were heavily damaged from the front wall of the store falling on them. The tornado continued to do very sporadic and more minor damage as it moved north of Highway 21, finally terminating at the Port of Savannah-Garden City. At the port, it pushed over some shipping containers and did minor damage to some container tanks in the area. The tornado then moved into the Savannah River and dissipated. This information can also be found on our website at weather.gov/chs. For reference: the Enhanced Fujita Scale classifies tornadoes into the following categories: EF0...Wind speeds 65 to 85 mph EF1...Wind speeds 86 to 110 mph EF2...Wind speeds 111 to 135 mph EF3...Wind speeds 136 to 165 mph EF4...Wind speeds 166 to 200 mph EF5...Wind speeds greater than 200 mph $$
Acknowledgments
Upper air analyses and mesoanalyses were obtained from the NOAA/NWS Storm Prediction Center. Surface analyses were obtained from the NOAA/NWS Weather Prediction Center. Local radar graphics were created using GR2Analyst version 2.60 for Windows.