On April 3âÂÂ4, 1974, a violent tornado outbreak described as the outbreak of the century caused widespread devastation across 13 states in the United States and 1 Canadian province. Dubbed the 1974 Super Outbreak and the Jumbo Outbreak, at least 149 tornadoes touched down in a 24-hour period. It is the second-largest continuous outbreak only behind the 2011 Super Outbreak which produced 358 tornadoes over a three-day period. However, the 1974 outbreak remains the most violent on record with 30 F4/5 tornadoes. At times, up to 15 tornadoes were on the ground simultaneously. A team of meteorologists led by Tetsuya Theodore Fujita studied the outbreak, compiling aerial surveys, ground surveys, photographs, and videos to construct a complete picture of the events. A total of 310âÂÂ335 fatalities and 5,454 to 6,142 injuries are attributed to the outbreak. Destruction of property was widespread and ruinous: 7,512 homes, 2,091 mobile homes, and 3,996 farm buildings were destroyed; 14,336 homes, 909 mobile homes, and 2,871 farm buildings suffered damage; 1,497 small businesses were damaged or destroyed. Total damage exceeded $600 million (1974 USD).
Activity occurred across three rounds throughout the 24-hour event, with the second and third being the most prolific.
The scale of destruction prompted sweeping changes in how public awareness of severe weather was handled and a reorganization of the National Weather Service itself. News broadcasters began running storm coverage beyond normal hours and local governments utilized the Emergency Broadcast System more frequently.
Prior to 1990, there is a likely undercount of tornadoes, particularly E/F0âÂÂ1, with reports of weaker tornadoes becoming more common as population increased. A sharp increase in the annual average E/F0âÂÂ1 count by approximately 200 tornadoes was noted upon the deployment of the NEXRAD Doppler weather radar network in 1990âÂÂ1991. 1974 marked the first year where significant tornado (E/F2+) counts became homogenous with contemporary values, attributed to the consistent implementation of Fujita Scale assessments. Numerous discrepancies on the details of tornadoes in this outbreak exist between sources. The total count of tornadoes and ratings differs from various agencies accordingly. The list below documents information from the most contemporary official sources alongside assessments from tornado historian Thomas Grazulis. All times are listed as described in Abbey and Fujita 1981 unless noted otherwise for consistency.
Multiple funnels were reported with the F5 Sayler Park tornado, two of which may have been distinct tornadoes. There is conflicting information on whether the damage from Waldron to Hudson, Michigan, was caused by one or two tornadoes. The Storm Data publication and NCEI database indicate two, nearly simultaneous F2 tornadoes originating near Waldron. However, Fujita and Grazulis list a single F2 tornado. The Storm Data publication lists a tornado that caused no damage north of Gibson City in Ford County, Illinois. This was not classified as a tornado by Fujita. Fujita initially analyzed a F0 tornado to the southwest of Cherry Log in Gilmer County, Georgia (Fujita tornado #122). This was later reclassified as a "tornado cyclone" rather than a true tornado. During the afternoon of April 4, two tornadoes touched down in southern Alabama. The Macon News listed that additional tornadoes were reported in Powder Springs, Douglasville, Austell, and Marietta. Although temporally close, they are not considered part of the Super Outbreak by Abbey and Fujita 1981 and Corfidi et al. 2010. The Richmond Times-Dispatch reported that a tornado caused damage to a horse farm and lumber yard in Kenbridge, Lunenburg County, Virginia, with a resident reporting a cone-shaped funnel. The two properties suffered $18,000 in damage.