A tornado is a violently rotating column of air that is in contact with both the surface of the Earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. It is often referred to as a twister, whirlwind or cyclone, although the word cyclone is used in meteorology to name a weather system with a low-pressure area in the center around which, from an observer looking down toward the surface of the Earth, winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern. Tornadoes come in many shapes and sizes, and they are often visible in the form of a condensation funnel originating from the base of a cumulonimbus cloud, with a cloud of rotating debris and dust beneath it. Most tornadoes have wind speeds less than 180 kilometers per hour, are about 80 meters across, and travel several kilometers before dissipating. The most extreme tornadoes can attain wind speeds of more than 480 kilometers per hour (300 mph), are more than 3 kilometers (2 mi) in diameter, and stay on the ground for more than 100 km (62 mi).
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), longest duration at about 3+1⁄2 hours, and it held the fastest forward speed for a significant tornado at 73 mph (117 km/h) anywhere on Earth until 2021. In addition, it is the deadliest single tornado in United States history with 695 fatalities. It was also the third most costly tornado in history at the time, when costs are normalized for wealth and inflation, it still ranks third today.
On February 19–20, 1884, one of the largest and most widespread tornado outbreaks in American history occurred over the Southeastern United States, known as the Enigma tornado outbreak due to the uncertain number of total tornadoes and fatalities. Nonetheless, an inspection of newspaper reports and governmental studies published in the aftermath reveals successive, long-tracked tornado families striking Alabama, Georgia, Illinois, Indiana, Kentucky, Mississippi, North Carolina, South Carolina, Tennessee and Virginia, with an estimation of at least 51—and possibly 60 or more—tornadoes.
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 deadliest on record to ever affect the state of Tennessee, with 66 of the fatalities associated with this outbreak occurring in the state; this surpasses the 60 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.
On March 21–22, 1932, a deadly tornado outbreak struck the Midwestern and Southern United States. At least 38 tornadoes—including 27 deadly tornadoes and several long-lived tornado families—struck the Deep South, killing more than 330 people and injuring 2,141. Tornadoes affected areas from Mississippi north to Illinois and east to South Carolina, but Alabama was hardest hit, with 268 fatalities; the outbreak is considered to be the deadliest ever in Alabama, and among the worst ever in the United States, trailing only the Tri-State tornado outbreak in 1925, with 751 fatalities, and the Tupelo–Gainesville outbreak in 1936, with 454 fatalities. The 1932 outbreak is believed to have produced 10 violent tornadoes, eight of which occurred in Alabama alone.
A deadly tornado outbreak affected much of the central and Southern United States from April 29 – May 1, 1909. Affecting particularly the Mississippi and Tennessee Valleys, it killed over 180 people, more than 90 of them in the U.S. state of Tennessee alone. The deadliest and longest-tracked tornado of the outbreak was a violent F4 tornado family that tracked across portions of northern Mississippi and western Tennessee on April 29, claiming at least 29 lives. Another deadly F4 tornado struck portions of southern Tennessee early the next day, killing 31. Other F4s in southern Missouri and southern Illinois on April 29 killed a combined 16 people. Deadly F3s in Georgia and Tennessee from April 30–May 1 killed a total of at least 53 people as well.
On April 19–21, 1920, a multi-day severe weather event affected the Southeastern United States. The most intense portion of the outbreak occurred on the morning of April 20. At least seven tornadoes affected the American U.S. states of Mississippi, Alabama, and Tennessee, six of them rated violent F4s on the Fujita scale. The tornado outbreak killed at least 243 people.
From April 27–29, 1912, a major tornado outbreak generated at least six violent tornadoes in Oklahoma, with near-constant activity until early the next day. At least 15 cities were affected, 40 people died, and 120 others were injured. Tornado researcher Thomas P. Grazulis considered this outbreak to be among the worst on record in the state of Oklahoma, as measured by fatalities and violent tornadoes. At least five strong tornadoes affected Washita County, Oklahoma, during this outbreak.
On April 20 – 22, 1912, a large tornado outbreak affected portions of the High Plains, the Upper Midwest, and the Southern United States, including portions of what is now known as the Dallas–Fort Worth metroplex. The severe-weather event produced at least 32 tornadoes, at least nine—and possibly 10 or more—of which were violent tornadoes, all of which rated F4 on the Fujita scale. Powerful tornado activity was distributed from the Great Plains to South Carolina. The first day of the outbreak occurred on April 20 and produced numerous strong to violent tornadoes across parts of North Texas, Oklahoma, and Kansas. A second day of intense tornadoes occurred on April 21, with several strong to violent tornadoes across Illinois and Indiana. The final day, April 22, produced an F4 tornado in Georgia as well. The entire outbreak killed 56 people, and was followed days later by another intense tornado outbreak on April 27. That outbreak killed about 40 people, mostly in Oklahoma. Both outbreaks produced a combined total of nine F4 tornadoes in Oklahoma alone.
On April 12, 1945, a tornado outbreak occurred in the Midwestern United States, producing numerous strong tornadoes and killing at least 128 people and injuring over 1,000 others; however, the concurrent death of President Franklin D. Roosevelt overshadowed news of the outbreak. On July 5, 1945, the United States Weather Bureau documented this entire outbreak as a single wind event, not a tornado or series of tornadoes, which killed 119 people and caused $2.65 million in damage. This report was later corrected on December 1, 1945, when the report was corrected to be a series of tornadoes. J. L. Baldwin, a meteorologist at the United States Weather Bureau office in Washington, D.C., later stated that, “these storms made April 12 the worst single day of tornado disaster[s] in the history of Oklahoma.”
On Thursday, September 29, 1927, an outbreak of at least 15 significant tornadoes, including three F3 tornadoes, killed at least 82 people in the Central United States, particularly in Missouri and Illinois. The outbreak affected a broad expanse of the Midwestern and Southern United States, including Oklahoma, Missouri, Arkansas, Iowa, Illinois, and Indiana. The deadliest tornado was an estimated F3 which affected portions of Greater St. Louis, killing at least 79 people and injuring at least 550 others. The tornado narrowly missed Downtown St. Louis, striking north of the central business district before crossing the Mississippi River.
Hurricane Isbell spawned one of the most significant tornado outbreaks to strike the Miami metropolitan area on October 14, 1964. It produced at least nine confirmed, and possibly as many as 17, tornadoes, four of which were rated significant (F2) on the Fujita scale. Although there were no fatalities, 48 people were injured and losses totaled $560,250. The most damaging of the tornadoes was an estimated F2 that injured 22 people at a mobile home park in Briny Breezes, causing $250,000 in losses.
Three deadly tornadoes impacted Wisconsin and Michigan on September 26, 1951. Both tornadoes in Wisconsin were violent while the one in Michigan was also significant. Eight people were killed, 15 others were injured, and damages were estimated at $750,000.
On January 4–6, 1946, a small but violent tornado outbreak struck the South-Central United States, killing 47 people and injuring at least 412 others. L. H. Seamon with the US Weather Bureau, the predecessor of the National Weather Service, later stated it was the "most disastrous" tornado event of the year; the US Weather Bureau stated in 1960 that January 4, 1946 had "outstanding tornadoes".
This is a timeline of scientific and technological advancements as well as notable academic or government publications in the area of atmospheric sciences and meteorology during the 21st century. Some historical weather events are included that mark time periods where advancements were made, or even that sparked policy change.
The history of tornado research spans back centuries, with the earliest documented tornado occurring in 200 and academic studies on them starting in the 18th century. This is a timeline of government or academic research into tornadoes.
