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).
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.
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, even though tornadoes were not ranked on any scale at the time. It 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, but has been surpassed by several others when non-normalized. When costs are normalized for wealth and inflation, it still ranks third today.
The TORRO tornado intensity scale is a scale measuring tornado intensity between T0 and T11. It was proposed by Terence Meaden of the Tornado and Storm Research Organisation (TORRO), a meteorological organisation in the United Kingdom, as an extension of the Beaufort scale.
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, Canada, France, China, and Mongolia.
Tornadoes are more common in the United States than in any other country or state. The United States receives more than 1,200 tornadoes annually—four times the amount seen in Europe. Violent tornadoes—those rated EF4 or EF5 on the Enhanced Fujita Scale—occur more often in the United States than in any other country.
The 2011 Super Outbreak was the largest, costliest, and one of the deadliest tornado outbreaks ever recorded, taking place in the Southern, Midwestern, and Northeastern United States from April 25 to 28, 2011, leaving catastrophic destruction in its wake. Over 175 tornadoes struck Alabama, Mississippi, and Tennessee, which were the most severely damaged states. Other destructive tornadoes occurred in Arkansas, Georgia, Kentucky, Louisiana, New York, and Virginia, with storms also affecting other states in the Southern and Eastern United States. In total, 360 tornadoes were confirmed by NOAA's National Weather Service (NWS) and Government of Canada's Environment Canada in 21 states from Texas to New York to southern Canada. Widespread and destructive tornadoes occurred on each day of the outbreak. April 27 was the most active day, with a record 216 tornadoes touching down that day from midnight to midnight CDT. Four of the tornadoes were rated EF5, which is the highest ranking on the Enhanced Fujita scale; typically these tornadoes are recorded no more than once a year.
From May 21 to May 26, 2011, one of the largest tornado outbreaks on record affected the Midwestern and Southern regions of the United States. A six-day tornado outbreak sequence, most of the tornadoes developed in a corridor from Lake Superior southwest to central Texas, while isolated tornadoes occurred in other areas. An especially destructive EF5 tornado destroyed one-third of Joplin, Missouri, resulting in 158 deaths and over 1,000 injuries. The Joplin tornado was the deadliest in the United States since April 9, 1947, when an intense tornado killed 181 in the Woodward, Oklahoma, area. Tornado-related deaths also occurred in Arkansas, Kansas, Minnesota, and Oklahoma. Overall, the tornado outbreak resulted in 186 deaths, 8 of those non-tornadic, making it second only to the 2011 Super Outbreak as the deadliest since 1974. It was the second costliest tornado outbreak in United States history behind that same April 2011 outbreak, with insured damage estimated at $4–7 billion.
During the late afternoon and early evening of April 27, 2011, a violent, high-end EF4 multiple-vortex tornado destroyed portions of Tuscaloosa and Birmingham, Alabama, as well as smaller communities and rural areas between the two cities. It is one of the costliest tornadoes on record, and was one of the 360 tornadoes in the 2011 Super Outbreak, the largest tornado outbreak in United States history. The tornado reached a maximum path width of 1.5 miles (2.4 km) during its track through Tuscaloosa, and again when it crossed I-65 north of Birmingham, attaining estimated wind speeds of 190 mph (310 km/h) shortly after passing through the city. It then went on to impact parts of Birmingham at high-end EF4 intensity before dissipating. This was the third tornado to strike the city of Tuscaloosa in the past decade, and the second in two weeks.
This page documents the tornadoes and tornado outbreaks of 2013. Strong and destructive tornadoes form most frequently in the United States, Bangladesh, Brazil and Eastern India, but they can occur almost anywhere under the right conditions. Tornadoes also appear regularly in neighboring southern Canada during the Northern Hemisphere's summer season, and somewhat regularly in Europe, Asia, and Australia.
This page documents the tornadoes and tornado outbreaks of 2014. Strong and destructive tornadoes form most frequently in the United States, Bangladesh, Brazil, and Eastern India, but they can occur almost anywhere under the right conditions. Tornadoes also appear regularly in neighboring southern Canada during the Northern Hemisphere's summer season, and somewhat regularly in Europe, Asia, and Australia.
The following is a glossary of tornado terms. It includes scientific as well as selected informal terminology.
The International Fujita scale rates the intensity of tornadoes and other wind events based on the severity of the damage they cause. It is used by the European Severe Storms Laboratory (ESSL) and various other organizations including Deutscher Wetterdienst (DWD) and State Meteorological Agency (AEMET). The scale is intended to be analogous to the Fujita and Enhanced Fujita scales, while being more applicable internationally by accounting for factors such as differences in building codes.
The 1764 Woldegk tornado was one of the strongest tornadoes ever documented in history, receiving the unique T11 rating on the TORRO scale along with an F5 rating on the Fujita scale and had winds estimated to be more than 480 kilometres per hour (300 mph). The tornado traveled 30 kilometres (19 mi) and reached a maximum width of 900 metres (980 yd). Most of the information known about this tornado came from a 77-paragraph detailed study by German scientist Gottlob Burchard Genzmer, which was published one year after the tornado occurred. The tornado completely destroyed several structures, and several tree branches were believed to have been thrown into the atmosphere. Many areas were covered with up to 2 centimetres (0.79 in) of ice. The storm which produced the violent tornado was dry, with almost no rain reported. Large hail, reportedly reaching 15 centimetres (5.9 in) in diameter covered the ground, caused significant crop and property damage, killed dozens of animals, and injured multiple people in a large stretch around the tornado and to the northwest of the tornado's path.