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), can be more than 3 kilometers (2 mi) in diameter, and can stay on the ground for more than 100 km (62 mi).
A tornado warning is a public warning that is issued by weather forecasting agencies to an area in the direct path of a tornado, or a severe thunderstorm capable of producing one, and advises individuals in that area to take cover. Modern weather surveillance technology such as Doppler weather radar can detect rotation in a thunderstorm, allowing for early warning before a tornado develops. They are also commonly issued based on reported visual sighting of a tornado, funnel cloud, or wall cloud, typically from weather spotters or the public, but also law enforcement or local emergency management. When radar is unavailable or insufficient, such ground truth is crucial. In particular, a tornado can develop in a gap of radar coverage, of which there are several known in the United States.
A tornado watch is a statement issued by weather forecasting agencies to advise the public that atmospheric conditions in a given region may lead to the development of tornadoes within the region over a period of several hours. In addition to the potential for tornado development, thunderstorms that develop within the watch area may contain large hail, straight-line winds, intense rainfall and/or flooding that pose a similar damage risk as the attendant tornado threat.
A severe thunderstorm watch is a statement issued by weather forecasting agencies to advise the public that atmospheric conditions in a given region may lead to the development of severe thunderstorms within the region over a period of several hours. The criteria for issuing a watch varies by country, and may also include torrential rainfall and tornadoes. A watch may also be issued several hours ahead of the arrival of a mature and organized complex of storms, or more clustered or discrete storm activity.
The National Weather Service (NWS) is an agency of the United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weather-related products to organizations and the public for the purposes of protection, safety, and general information. It is a part of the National Oceanic and Atmospheric Administration (NOAA) branch of the Department of Commerce, and is headquartered in Silver Spring, Maryland, within the Washington metropolitan area. The agency was known as the United States Weather Bureau from 1891 until it adopted its current name in 1970.
On March 18, 1925, one of the deadliest tornado outbreaks in recorded history generated at least 12 significant tornadoes and spanned a large portion of the midwestern and southern United States. In all, at least 751 men, women and children were killed and more than 2,298 were injured, making the outbreak the deadliest tornado outbreak in U.S. history. The outbreak generated several destructive tornadoes in Missouri, Illinois, and Indiana on the same day, as well as significant tornadoes in Alabama and Kansas. In addition to confirmed tornadoes, there were undoubtedly others with lesser impacts, the occurrences of which have been lost to history.
The 1965 Palm Sunday tornado outbreak was a historic severe weather event that affected the Midwestern and Southeastern United States on April 10–12, 1965. The tornado outbreak produced 55 confirmed tornadoes in one day and 16 hours. The worst part of the outbreak occurred during the afternoon hours of April 11 into the overnight hours going into April 12. The second-largest tornado outbreak on record at the time, this deadly series of tornadoes inflicted a swath of destruction from Cedar County, Iowa, to Cuyahoga County, Ohio, and a swath 450 miles long (724 km) from Kent County, Michigan, to Montgomery County, Indiana. The main part of the outbreak lasted 16 hours and 35 minutes and is among the most intense outbreaks, in terms of tornado strength, ever recorded, including at least four "double/twin funnel" tornadoes. In all, the outbreak killed 266 people, injured 3,662 others, and caused $1.217 billion in damage. In 2023, tornado expert Thomas P. Grazulis created the outbreak intensity score (OIS) as a way to rank various tornado outbreaks. The 1965 Palm Sunday tornado outbreak received an OIS of 238, making it the fourth worst tornado outbreak in recorded history.
From May 2 to 8, 1999, a large tornado outbreak took place across much of the Central and parts of the Eastern United States, as well as southern Canada. During this week-long event, 152 tornadoes touched down in these areas. The most dramatic events unfolded during the afternoon of May 3 through the early morning hours of May 4 when more than half of these storms occurred. Oklahoma experienced its largest tornado outbreak on record, with 70 confirmed. The most notable of these was the F5 Bridge Creek–Moore tornado which devastated Oklahoma City and suburban communities. The tornado killed 36 people and injured 583 others; losses amounted to $1 billion, making it the first billion-dollar tornado in history. Overall, 50 people lost their lives during the outbreak and damage amounted to $1.4 billion. For these reasons, the outbreak is known in Oklahoma as the May 3rd outbreak or the Oklahoma tornado outbreak of 1999.
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 Storm Prediction Center (SPC) is a US government agency that is part of the National Centers for Environmental Prediction (NCEP), operating under the control of the National Weather Service (NWS), which in turn is part of the National Oceanic and Atmospheric Administration (NOAA) of the United States Department of Commerce (DoC).
The 1994 Palm Sunday tornado outbreak was the third notable US tornado outbreak to occur on Palm Sunday and the second to take place in the Southeastern United States. The outbreak produced 29 tornadoes from Texas to North Carolina, killing 40 people and injuring 491, and causing $140 million in damage. The deadliest storm of the outbreak, as well as in the US in 1994, was an F4 tornado that devastated Piedmont, Alabama. It struck the Goshen United Methodist Church right in the middle of the Palm Sunday service, collapsing the roof on the congregation and killing 20 people inside, including the Rev. Kelly Clem's 4-year-old daughter Hannah. Two other houses of worship were also destroyed mid-service. The supercell that formed this tornado tracked for 200 miles (322 km) to South Carolina.
On March 28, 1920, a large outbreak of at least 37 tornadoes, 31 of which were significant, took place across the Midwestern and Southern United States. The tornadoes left at least 153 dead and at least 1,215 injured. Many communities and farmers alike were caught off-guard as the storms moved to the northeast at speeds that reached over 60 mph (97 km/h). Most of the fatalities occurred in Georgia (37), Ohio (28), and Indiana (21), while the other states had lesser totals. Little is known about many of the specific tornadoes that occurred, and the list below is only partial.
Joseph G. Galway, was an American meteorologist pioneering in the fields of severe convective storm forecasting and research. He was one of the first forecasters for the Severe Local Storms Unit and the National Severe Storms Forecast Center, and developed widely used synoptic predictors associated with severe thunderstorms and tornadoes, such as the jet streak and lifted index.
Convective storm detection is the meteorological observation, and short-term prediction, of deep moist convection (DMC). DMC describes atmospheric conditions producing single or clusters of large vertical extension clouds ranging from cumulus congestus to cumulonimbus, the latter producing thunderstorms associated with lightning and thunder. Those two types of clouds can produce severe weather at the surface and aloft.
From May 3 to May 11, 2003, a prolonged and destructive series of tornado outbreaks affected much of the Great Plains and Eastern United States. Most of the severe activity was concentrated between May 4 and May 10, which saw more tornadoes than any other week-long span in recorded history; 335 tornadoes occurred during this period, concentrated in the Ozarks and central Mississippi River Valley. Additional tornadoes were produced by the same storm systems from May 3 to May 11, producing 363 tornadoes overall, of which 62 were significant. Six of the tornadoes were rated F4, and of these four occurred on May 4, the most prolific day of the tornado outbreak sequence; these were the outbreak's strongest tornadoes. Damage caused by the severe weather and associated flooding amounted to US$4.1 billion, making it the costliest U.S. tornado outbreak of the 2000s. A total of 50 deaths and 713 injuries were caused by the severe weather, with a majority caused by tornadoes; the deadliest tornado was an F4 that struck Madison and Henderson counties in Tennessee, killing 11. In 2023, tornado expert Thomas P. Grazulis created the outbreak intensity score (OIS) as a way to rank various tornado outbreaks. The tornado outbreak sequence of May 2003 received an OIS of 232, making it the fourth worst tornado outbreak in recorded history.
The 1999 Bridge Creek–Moore tornado was a large, long-lived and exceptionally powerful F5 tornado in which the highest wind speed ever measured globally was recorded at 321 miles per hour (517 km/h) by a Doppler on Wheels (DOW) radar. Considered the strongest tornado ever recorded to have affected the Oklahoma City metropolitan area, the tornado devastated southern portions of Oklahoma City, Oklahoma, United States while near peak intensity, along with surrounding suburbs and towns to the south and southwest of the city during the early evening of Monday, May 3, 1999. Parts of Bridge Creek were rendered unrecognizable. The tornado covered 38 miles (61 km) during its 85-minute existence, destroying thousands of homes, killing 36 people, and leaving US$1 billion in damage, ranking it as the fifth-costliest on record not accounting for inflation. Its severity prompted the first-ever use of the tornado emergency statement by the National Weather Service.
On December 18–20, 1957, a significant tornado outbreak sequence affected the southern Midwest and the South of the contiguous United States. The outbreak sequence began on the afternoon of December 18, when a low-pressure area approached the southern portions of Missouri and Illinois. Supercells developed and proceeded eastward at horizontal speeds of 40 to 45 miles per hour, yielding what was considered the most severe tornado outbreak in Illinois on record so late in the calendar year. Total losses in the state were estimated to fall within the range of $8–$10 million.
National Weather Service - Norman, Oklahoma is a Weather Forecast Office (WFO) of the National Weather Service based in Norman, Oklahoma, which is responsible for forecasts and the dissemination of weather warnings and advisories for central and most of western Oklahoma, and western portions of north Texas. It is located in the National Weather Center on the University of Oklahoma campus, where it acts as one of the NOAA Weather Partners, a group of close-together weather-related agencies of the National Oceanic and Atmospheric Administration. NWS Norman is currently overseen by Mark Fox, who serves as the Meteorologist In Charge of the office.
Larry F. Wilson is an American meteorologist who specializes in the forecasting of severe convective storms. For many years Wilson served as a lead forecaster at the National Severe Storms Forecast Center in Kansas City, Missouri. As a U.S. Air Force (USAF) meteorologist in the mid-1960s, Wilson is one of only two NSSFC forecasters to have ever worked directly with severe weather forecasting pioneer Colonel Robert C. Miller (1920-1998).
