Severe weather occurs in South Carolina occasionally in the form of violent thunderstorms and tornadoes. Although less frequent than surrounding states, thunderstorms are common in the summer months. The more violent storms generally accompany squall lines and active cold fronts of late-winter or spring. Strong thunderstorms usually bring high winds, hail, considerable lightning, and rarely spawn a tornado.
Hail occurs infrequently, falling most often during spring thunderstorms from March through May. The incidence of hail varies from 1 to 1.5 hail days per year in the Midlands, Piedmont, and Foothills to 0.5 days per year in the Lowcountry (Coffey, 1988). Although hail can occur in every month during the year, May has the highest incidence with an average of more than 5 events per year. Typically, it occurs during the late afternoon and early evening between the hours of 3:00 p.m. and 8:00 p.m. (Knupp, 1992).
Annual Distribution of Tornadoes
In the 60-year period from 1950 through 2009 an average of 15 tornadoes occurred per year in South Carolina. In the 20 year period from 1990 to 2009 the annual average was 28 tornadoes per year. This dramatic increase is primarily attributable to the implementation of the National Weather Service's advanced NEXRAD Doppler radar system which is able to pinpoint tornadic vortex signatures State-wide, unlike previous NWS radar systems.
During spring, tornadoes result from active cold fronts, whereas during summer and early fall many are associated with the passage of tropical cyclones. During November and December, it is not uncommon to have active cold fronts and tornadic activity. Tornado frequency is at a minimum in October and January; only 3% of the total are experienced during these two months.
September 6-7, 2004:Tropical Storm Frances triggered a record 47 tornadoes as it tracked up the spine of the Appalachians. The National Weather Service, using the F0-F5 Fujita scale, identified 26 F0s, 17 F1s, 3 F2s and 1 F3 during the 2-day period. 43 tornadoes touched down on September 7, setting a new one day record. The 47 tornadoes caused widespread damage in the Low Country, Midlands and Pee Dee. Sumter County experienced the worst damage. An F2 destroyed 9 Sumter County homes, damaged 55 homes, injured 3 people and caused over $1.7 million dollars worth of damage. Kershaw County was struck by the F3 tornado which demolished several cinder block stables and deftly picked up a large horse trailer and placed it on the roof of another stable. This record setting tornado outbreak injured 13 and inflicted $2.77 million in total state-wide damages.
August 16, 1994: An outbreak of 22 confirmed tornadoes occurred when the remnants of Tropical Storm Beryl merged with a cold front. The tornadoes damaged homes and buildings in a very narrow band running north from Bamberg County through Lancaster and York Counties. One tornado hit the Town of Lexington's central business district. There were no deaths, at least 40 injuries, and over $50 million in damage.
March 28, 1984: The second highest loss of life from tornadoes occurred when 11 tornadoes touched down along a narrow band that extended from Anderson County through Marlboro County. These tornadoes caused 15 deaths, 448 injuries, and damage of over $100 million. These tornadoes also caused several other storm related fatalities.
April 30, 1924: The highest tornado death toll in South Carolina's history occurred on this date when two tornadoes struck. The paths of both were unusually long; each over 100 miles long. Together they killed 77 persons, injured 778 more, destroyed 465 homes and many other buildings resulting in many millions of dollars of damage. One tornado remained on the ground from Anderson County to York County; the other, which as been named "The Horrell Hill Tornado", was the more destructive of the two. Its path was 135 miles from Aiken County to Florence County.