The Fujita scale, or Fujita–Pearson scale, is a scale for rating tornado intensity, based primarily on the damage tornadoes inflict on human-built structures and vegetation. The official Fujita scale category is determined by meteorologists and engineers after a ground or aerial damage survey, or both; and depending on the circumstances, ground-swirl patterns, weather radar data, witness testimonies, media reports and damage imagery, as well as photogrammetry or videogrammetry if motion picture recording is available. The Fujita scale was replaced with the Enhanced Fujita scale (EF-Scale) in the United States in February 2007. In April 2013, Canada adopted the EF-Scale over the Fujita scale along with 31 "Specific Damage Indicators" used by Environment Canada (EC) in their ratings.
From April 26 to 27, 1991, multiple supercells across Oklahoma and Kansas led to a regional tornado outbreak. Forced by a potent trough and focused along a dryline, these distinct thunderstorms moved northeast through a moist and highly unstable environment. A total of 55 tornadoes were confirmed, many of which were strong, F2 or greater on the Fujita scale. A widely documented F5 tornado tore through Andover, Kansas, killing 17 people. Additional fatalities occurred from significant tornadoes in other portions of Kansas and Oklahoma, with 21 deaths recorded in total. An F4 tornado was detected by a mobile doppler weather radar team which observed winds up to 270 mph (430 km/h) at the top of the funnel, the first time winds of F5 intensity were measured by radar, and the highest winds recorded by radar at the time. A news team filming an F2 tornado sought shelter under a Kansas Turnpike overpass, causing a misconception that overpasses can provide adequate shelter during a tornado. This outbreak occurred within a transition period for the National Weather Service and proved the value of NEXRAD radars, which were utilized in Oklahoma to provide advanced warning to residents.
This article lists various tornado records. The most "extreme" tornado in recorded history was the Tri-State tornado, which spread through parts of Missouri, Illinois, and Indiana on March 18, 1925. It is considered an F5 on the Fujita Scale, holds records for longest path length at 219 miles (352 km) and longest duration at about 3+1⁄2 hours. The 1974 Guin tornado had the highest forward speed ever recorded in a violent tornado, at 75 mph (121 km/h). The deadliest tornado in world history was the Daulatpur–Saturia tornado in Bangladesh on April 26, 1989, which killed approximately 1,300 people. In the history of Bangladesh, at least 19 tornadoes killed more than 100 people each, almost half of the total for the world. The most extensive tornado outbreak on record was the 2011 Super Outbreak, which resulted in 367 tornadoes and 324 tornadic fatalities, whereas the 1974 Super Outbreak was the most intense tornado outbreak on tornado expert Thomas P. Grazulis's outbreak intensity score with 578, as opposed to the 2011 outbreak's 378.
The Enhanced Fujita scale rates tornado intensity based on the severity of the damage they cause. It is used in some countries, including the United States and France. The EF scale is also unofficially used in other countries, including China.
Tornado intensity is the measure of wind speeds and potential risk produced by a tornado. Intensity can be measured by in situ or remote sensing measurements, but since these are impractical for wide-scale use, intensity is usually inferred by proxies, such as damage. The Fujita scale, Enhanced Fujita scale, and the International Fujita scale rate tornadoes by the damage caused. In contrast to other major storms such as hurricanes and typhoons, such classifications are only assigned retroactively. Wind speed alone is not enough to determine the intensity of a tornado. An EF0 tornado may damage trees and peel some shingles off roofs, while an EF5 tornado can rip well-anchored homes off their foundations, leaving them bare— even deforming large skyscrapers. The similar TORRO scale ranges from a T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes. Doppler radar data, photogrammetry, and ground swirl patterns may also be analyzed to determine the intensity and assign a rating.
A violent severe weather outbreak struck the Southeast on April 4–5, 1977. A total of 22 tornadoes touched down with the strongest ones occurring in Mississippi, Alabama, and Georgia. The strongest was a catastrophic F5 tornado that struck the northern Birmingham, Alabama, suburbs during the afternoon of Monday, April 4. In addition to this tornado, several other tornadoes were reported from the same system in the Midwest, Alabama, Georgia, Mississippi and North Carolina. One tornado in Floyd County, Georgia, killed one person, and another fatality was reported east of Birmingham in St. Clair County. In the end, the entire outbreak directly caused 24 deaths and 158 injuries. The storm system also caused the crash of Southern Airways Flight 242, which killed 72 and injured 22.
On March 21–22, 1952, a severe tornado outbreak generated eight violent tornadoes across the Southern United States, causing 209 fatalities—50 of which occurred in a single tornado in Arkansas. In addition, this tornado outbreak is the second deadliest on record to ever affect the state of Tennessee, with 66 of the fatalities associated with this outbreak occurring in the state; this is only surpassed by the 90 fatalities from a tornado outbreak in 1909, and in terms of fatalities is well ahead of both the 1974 Super Outbreak and the Super Tuesday tornado outbreak, each of which generated 45 and 31 fatalities, respectively. The severe weather event also resulted in the fourth-largest number of tornado fatalities within a 24-hour period since 1950. To date this was considered the most destructive tornado outbreak in Arkansas on record.
A deadly tornado outbreak devastated parts of Louisiana and Tennessee on February 11–13, 1950. The outbreak covered about a day and a half and produced numerous tornadoes, mostly from East Texas to the lower Mississippi Valley, with activity concentrated in Texas and Louisiana. Most of the deaths occurred in Louisiana and Tennessee, where tornadoes killed 25 and 9 people, respectively. Several long-lived tornado families struck the Red River region of northwestern Louisiana, especially the Shreveport–Bossier City area. One of the tornadoes attained violent intensity, F4, on the Fujita scale and caused eight deaths, including six at the Shreveport Holding and Reconsignment Depot near Barksdale Air Force Base. It remains one of the top ten deadliest tornadoes on record in the state of Louisiana, in tenth place. Also in Louisiana, two other destructive tornadoes on parallel paths killed 16. Seven additional deaths occurred across the border in East Texas. Nine people died in a tornado in western Tennessee as well. In all, the entire outbreak killed at least 41 people and left 228 injured. Also, several long-tracked tornadoes recorded in the outbreak likely contained more, shorter-lived tornadoes.
A widespread, destructive, and deadly tornado outbreak sequence affected the Southeastern United States from April 28 to May 2, 1953, producing 24 tornadoes, including five violent F4 tornadoes. The deadliest event of the sequence was an F4 tornado family that ravaged Robins Air Force Base in Warner Robins, Georgia, on April 30, killing at least 18 people and injuring 300 or more others. On May 1, a pair of F4 tornadoes also struck Alabama, causing a combined nine deaths and 15 injuries. Additionally, another violent tornado struck rural Tennessee after midnight on May 2, killing four people and injuring eight. Additionally, two intense tornadoes impacted Greater San Antonio, Texas, on April 28, killing three people and injuring 20 altogether. In all, 36 people were killed, 361 others were injured, and total damages reached $26.713 million (1953 USD). There were additional casualties from non-tornadic events as well, including a washout which caused a train derailment that injured 10.
On November 7–8, 1957, a significant tornado outbreak affected portions of the Southern United States, particularly the Golden Triangle of Southeast Texas and parts of Acadiana in Louisiana. The severe weather event inflicted 12 deaths and more than 200 injuries, especially in the vicinity of Beaumont and Port Arthur, Texas. The most intense tornado of the outbreak, retrospectively rated F4 on the Fujita scale, struck the town of Orange, Texas, killing one person, injuring 81 others, and causing $11⁄2 million in losses. The deadliest tornado of the outbreak was an F3 that killed four people northwest of Carencro, Louisiana. The costliest tornado of the outbreak, also rated F3, caused $2.3 million in losses in the town of Groves, Texas, killing a few people there. Other intense tornadoes occurred as far east as Mississippi and North Carolina. In all, at least 28 tornadoes were confirmed, yet others were likely present as well.
Five scattered tornadoes touched down across the Great Plains and Midwestern United States on June 19, 1951. The event was highlighted by a large, violent F4 tornado family that moved through the western and northern suburbs of Minneapolis, causing all the tornadic casualties from the outbreak. In all, one person was killed, 20 others were injured, and damage was estimated at $59 million. There was one additional death and six injuries from non-tornadic events as well.
Several destructive tornadoes struck the Southeastern United States, primarily along and east of the Lower Mississippi Valley, on February 13, 1952. Multiple intense tornadoes touched down throughout the day, three of which were killers. The deadliest and most destructive tornado of the outbreak was a violent F4 that touched down in south-central Tennessee, killing three people and injuring 44 others. A similarly destructive tornado—albeit of weaker, F2 intensity—formed from the same storm as the preceding F4 and became the second costliest of the outbreak. Another intense tornado affected the Mississippi embayment near Manila, Arkansas, injuring five people, and a pair of deadly F3s in Alabama claimed a combined two lives. In all, the outbreak killed five people and injured 102 others.
On the afternoon of July 8, 2020, a violent and deadly drillbit tornado struck the area between the towns of Ashby and Dalton, Minnesota. The National Weather Service in Grand Forks, North Dakota rated the worst of the damage from the tornado EF4 on the Enhanced Fujita scale. The tornado was also used as the cover for the 2021 disaster film 13 Minutes.
