On April 3–4, 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 310–335 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/F0–1, with reports of weaker tornadoes becoming more common as population increased. A sharp increase in the annual average E/F0–1 count by approximately 200 tornadoes was noted upon the deployment of the NEXRAD Doppler weather radar network in 1990–1991. 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.
Confirmed tornadoes + Daily statistics of tornadoes during the Super Outbreak of April 3–4, 1974 DateTotalFujita scale ratingDeathsInjuriesDamage F0 F1 F2 F3 F4 F5 April 3130 12 24 33 31 23 7 10–11211–254> April 419 6 8 2 3 0 0 Total149 18 32 35 34 23 7310–3355,454–6,142~
+ Color/symbol key Color / symbol Description § Data from Shamburger 2015, 2021/2022 † Data from Grazulis 1990/1993 ♭ Data from Abbey and Fujita 1981 ¶ Data from a local National Weather Service office ※ Data from the 1974 Storm Data publication ‡ Data from the NCEI database ♯ Maximum width of tornado
+ Confirmed tornadoes during the Super Outbreak of April 3–4, 1974F#LocationCounty / ParishStateCoord.DateTime (UTC)Path lengthWidthSummary F2NE of WhitestownBooneIN13:30‡※※A tornado touched down over an open field. It is listed as a F2 tornado in the National Centers for Environmental Information (NCEI) database; however, Grazulis did not include it in his Significant Tornadoes book and it is not depicted in Ted Fujita's outbreak map. This tornado was produced by a mesoscale convective system that developed ahead of the two main rounds of tornadic activity. F0MorrisGrundyIL18:10–18:11B♭ ‡This was the first tornado associated with the outbreak listed by Fujita. The Storm Data publication lists this event as a funnel cloud that did not reach the ground; accompanying winds caused $1,000 in damage. F2Ellijay to Blue RidgeGilmer, FanninGA18:50–19:20B††5 injuries — This strong tornado caused extensive damage to homes—some of which had their roof torn off or were otherwise destroyed—trees, and power lines. Five people were injured and losses reached $800,000. The tornado moved close to Cherry Log, damaging several homes in the area. The community of Aska was impacted before the tornado crossed Blue Ridge Lake, damaging homes in the area. Newspaper reports indicate the tornado lifted near Blue Ridge and touched back down near Hemp where one home and several farm buildings were destroyed. 1-A, 14-A Sources differ significantly on the timing of this tornado: the NCEI database lists the tornado as occurring at 18:00 UTC, Grazulis lists 19:15 UTC, and the Storm Data publication lists 23:30 UTC. F1EtowahMcMinnTN19:00–19:05D¶¶♯This was the first of two tornadoes to impact Etowah. Damage from this tornado is unspecified; the combined effects are listed under the second Etowah tornado. F1S of Lincoln to McLeanLogan, McLeanIL19:03–19:19A♭‡This tornado moved northeast at a fast pace, roughly . It caused $600,000 in property damage in McLean. F1N of West Baden Springs to E of MitchellOrange, LawrenceIN19:03–19:20B♭‡1 death, 4 injuries — This tornado moved along an intermittent path. South of Orleans, a mobile home and an unoccupied home were destroyed; two people were injured in the former. Another home east of Spring Mill State Park in the Stonington area was destroyed with both occupants injured. A metal shed on the property was blown away and could not be found. Two other homes suffered minor damage. Several trees and power lines were snapped or uprooted. The Storm Data publication lists one fatality and four injuries while the NCEI database lists none. F3SW of Cleveland to N of BentonBradley, PolkTN19:03–19:26B†¶#1 death. 100 injuries — This was one of two tornadoes to impact areas around Cleveland. Extensive damage to occurred to many homes. A trailer park east of Cleveland was almost completely destroyed, with only 1 of 20 remaining; one person died here. At least 120 homes were damaged, of which 73 were destroyed, in Cleveland. A-1, A-12 A total of 100 people were injured and damage reached $4.5 million. F0E of CarlockMcLeanIL19:07–19:08A♭ ‡A tornado was reported without causing damage. F0Mountain CityRabunGA19:09–19:10D♭Details on this tornado are unspecified. This tornado was omitted from the NCEI database. F3E of Mitchell to ENE of AzaliaLawrence, Jackson, Bartholomew, JenningsIN19:15–20:05B†‡1 death, 23 injuries — This tornado moved along an intermittent path, causing extensive damage to farms. A block foundation poultry building, egg farm, and barn were destroyed north of Medora. A well-anchored mobile home was torn from its frame and obliterated, killing the occupant. Continuing toward Jonesville, the tornado caused extensive damage to homes, mobile homes, and farm buildings. A high tension power line collapsed along I-65. "Extreme damage" took place in areas near Acme and Freetown.