Tornado Alley is a loosely defined area of the central

United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territorie ...

where

tornado 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, altho ...

es are most frequent. The term was first used in 1952 as the title of a

research project Research is "creative and systematic work undertaken to increase the stock of knowledge". It involves the collection, organization and analysis of evidence to increase understanding of a topic, characterized by a particular attentiveness t ...

to study

severe weather Severe weather is any dangerous meteorological phenomenon with the potential to cause damage, serious social disruption, or loss of human life. Types of severe weather phenomena vary, depending on the latitude, altitude, topography, and atmos ...

in areas of

Texas Texas (, ; Spanish language, Spanish: ''Texas'', ''Tejas'') is a state in the South Central United States, South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2 ...

Louisiana Louisiana , group=pronunciation (French: ''La Louisiane'') is a state in the Deep South and South Central regions of the United States. It is the 20th-smallest by area and the 25th most populous of the 50 U.S. states. Louisiana is borde ...

Oklahoma Oklahoma (; Choctaw language, Choctaw: ; chr, ᎣᎧᎳᎰᎹ, ''Okalahoma'' ) is a U.S. state, state in the South Central United States, South Central region of the United States, bordered by Texas on the south and west, Kansas on the nor ...

Kansas Kansas () is a state in the Midwestern United States. Its capital is Topeka, and its largest city is Wichita. Kansas is a landlocked state bordered by Nebraska to the north; Missouri to the east; Oklahoma to the south; and Colorado to the ...

South Dakota South Dakota (; Sioux language, Sioux: , ) is a U.S. state in the West North Central states, North Central region of the United States. It is also part of the Great Plains. South Dakota is named after the Lakota people, Lakota and Dakota peo ...

Iowa Iowa () is a state in the Midwestern region of the United States, bordered by the Mississippi River to the east and the Missouri River and Big Sioux River to the west. It is bordered by six states: Wisconsin to the northeast, Illinois to the ...

and

Nebraska Nebraska () is a state in the Midwestern region of the United States. It is bordered by South Dakota to the north; Iowa to the east and Missouri to the southeast, both across the Missouri River; Kansas to the south; Colorado to the southwe ...

. Tornado climatologists distinguish peaks in activity in certain areas and

storm chasers ''Storm Chasers'' is an American documentary reality television series that premiered on October 17, 2007, on the Discovery Channel. Produced by Original Media, the program follows several teams of storm chasers as they attempt to intercept ...

have long recognized the

Great Plains The Great Plains (french: Grandes Plaines), sometimes simply "the Plains", is a broad expanse of flatland in North America. It is located west of the Mississippi River and east of the Rocky Mountains, much of it covered in prairie, steppe, an ...

tornado belt. Although the official boundaries of Tornado Alley are not clearly defined, the main alley extends from northern

, through

, and

. States such as

Minnesota Minnesota () is a state in the upper midwestern region of the United States. It is the 12th largest U.S. state in area and the 22nd most populous, with over 5.75 million residents. Minnesota is home to western prairies, now given over to ...

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...

Illinois Illinois ( ) is a U.S. state, state in the Midwestern United States, Midwestern United States. Its largest metropolitan areas include the Chicago metropolitan area, and the Metro East section, of Greater St. Louis. Other smaller metropolita ...

Indiana Indiana () is a U.S. state in the Midwestern United States. It is the 38th-largest by area and the 17th-most populous of the 50 States. Its capital and largest city is Indianapolis. Indiana was admitted to the United States as the 19th s ...

Missouri Missouri is a U.S. state, state in the Midwestern United States, Midwestern region of the United States. Ranking List of U.S. states and territories by area, 21st in land area, it is bordered by eight states (tied for the most with Tennessee ...

Arkansas Arkansas ( ) is a landlocked state in the South Central United States. It is bordered by Missouri to the north, Tennessee and Mississippi to the east, Louisiana to the south, and Texas and Oklahoma to the west. Its name is from the Osage ...

North Dakota North Dakota () is a U.S. state in the Upper Midwest, named after the Native Americans in the United States, indigenous Dakota people, Dakota Sioux. North Dakota is bordered by the Canadian provinces of Saskatchewan and Manitoba to the north a ...

Montana Montana () is a state in the Mountain West division of the Western United States. It is bordered by Idaho to the west, North Dakota and South Dakota to the east, Wyoming to the south, and the Canadian provinces of Alberta, British Columbi ...

, and

Ohio Ohio () is a state in the Midwestern region of the United States. Of the fifty U.S. states, it is the 34th-largest by area, and with a population of nearly 11.8 million, is the seventh-most populous and tenth-most densely populated. The sta ...

are sometimes included in Tornado Alley, as are the easternmost portions of

Colorado Colorado (, other variants) is a state in the Mountain West subregion of the Western United States. It encompasses most of the Southern Rocky Mountains, as well as the northeastern portion of the Colorado Plateau and the western edge of t ...

and

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

. Research suggests that the main alley may be shifting eastward away from the Great Plains, and that tornadoes are also becoming more frequent in the northern parts of Tornado Alley where it reaches the

Canadian prairies The Canadian Prairies (usually referred to as simply the Prairies in Canada) is a region in Western Canada. It includes the Canadian portion of the Great Plains and the Prairie Provinces, namely Alberta, Saskatchewan, and Manitoba. These provin ...

Geographical area

Over the years, the location(s) of Tornado Alley have not been clearly defined. No definition of tornado alley has ever been officially designated by the

National Weather Service The National Weather Service (NWS) is an Government agency, agency of the Federal government of the United States, United States federal government that is tasked with providing weather forecasts, warnings of hazardous weather, and other weathe ...

(NWS). Thus, differences in location are the result of the different criteria used. According to the

National Severe Storms Laboratory The National Severe Storms Laboratory (NSSL) is a National Oceanic and Atmospheric Administration (NOAA) weather research laboratory under the Office of Oceanic and Atmospheric Research. It is one of seven NOAA Research Laboratories (RLs). NSSL ...

(NSSL) FAQ, "Tornado Alley" is a term used by the media as a reference to areas that have higher numbers of tornadoes. A study of 1921–1995 tornadoes concluded almost one-fourth of all significant tornadoes occur in this area. Although the official boundaries of Tornado Alley are not clearly defined, its core extends from northern

along with

, and western

are sometimes included in Tornado Alley. Some research suggests that tornadoes are becoming more frequent in the northern parts of Tornado Alley where it reaches the

. No place on earth is entirely free of tornadoes, however, they occur much more frequently in the

, particularly in the Central states, between the

Rocky Mountains The Rocky Mountains, also known as the Rockies, are a major mountain range and the largest mountain system in North America. The Rocky Mountains stretch in straight-line distance from the northernmost part of western Canada, to New Mexico in ...

to the west and

Appalachian Mountains The Appalachian Mountains, often called the Appalachians, (french: Appalaches), are a system of mountains in eastern to northeastern North America. The Appalachians first formed roughly 480 million years ago during the Ordovician Period. They ...

to the east. Texas has the most overall number of tornadoes of any state. Per data collected through 2007, Kansas and Oklahoma ranked first and second respectively in the number of tornadoes per area. However, in 2013 statistics from the

National Climatic Data Center The United States National Climatic Data Center (NCDC), previously known as the National Weather Records Center (NWRC), in Asheville, North Carolina, was the world's largest active archive of weather data. Starting as a tabulation unit in New Orl ...

reported Florida ranked first in tornadoes per area, although Florida is not a part of Tornado Alley. Florida's high ranking on the tornado list also has to do with the fact that the state sees a high number of

waterspout A waterspout is an intense columnar vortex (usually appearing as a funnel cloud, funnel-shaped cloud) that occurs over a body of water. Some are connected to a cumulus congestus cloud, some to a cumuliform cloud and some to a cumulonimbus clou ...

s, small tornadoes that form over water. Although strong land-tornadoes have hit Florida and reports show Florida has a very high number of overall tornadoes, the tornadoes in the state seldom reach the velocity of those that may occur in the Southern Plains. In the United States, tornadoes typically occur in late spring and early summer during the changing season patterns as a warm air mass typically collides with a cold air mass resulting in tornadoes. Another criterion for the location of Tornado Alley can be where the strongest tornadoes occur more frequently. Tornado Alley can also be defined as an area reaching from central Texas to the Canadian prairies and from eastern Colorado to western Ohio. It has also been asserted that there may be numerous Tornado Alleys. In addition to the Texas/Oklahoma/Kansas core, such other areas include the Upper Midwest, the lower Ohio Valley, the Tennessee Valley, and the lower Mississippi valley. Some studies, however, suggest that there is one Tornado Alley in the United States and that it can simply be subdivided into smaller tornado alleys based on regional categories. The tornado alleys in the southeastern U.S., notably the lower

Mississippi Valley The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it ...

and the upper

Tennessee Valley The Tennessee Valley is the drainage basin of the Tennessee River and is largely within the U.S. state of Tennessee. It stretches from southwest Kentucky to north Alabama and from northeast Mississippi to the mountains of Virginia and North Car ...

, are sometimes called by the nickname "

Dixie Alley "Dixie Alley" is a colloquial term sometimes used for areas of the southern United States which are particularly vulnerable to strong to violent tornadoes. Some argue this is distinct from the better known "Tornado Alley" and that it has a high f ...

", coined in 1971 by Allen Pearson, former director of the National Severe Storms Forecasting Center (NSSFC). A 2018 study found in the U.S., over the study period 1979-2017, an overall eastward shift of tornado frequency and impacts - toward Dixie Alley. The study found, since 1979, relatively-lower tornado frequency and impacts in parts of the traditional Tornado Alley, especially areas from north-central Texas toward the Houston, TX area, and relatively-higher tornado frequency and impacts in parts of the Mid-South, especially eastern Arkansas, the greater Memphis, TN area and northern Mississippi - all areas near the heart of Dixie Alley - see especially Figure 4. In Tornado Alley, warm, humid air from the equator meets cool to cold, dry air from Canada and the

. This creates an ideal environment for tornadoes to form within developed thunderstorms and super cells.

Origin of the term

The term "tornado alley" was first used in 1952 by U.S. Air Force meteorologists Major Ernest J. Fawbush (1915–1982) and Captain Robert C. Miller (1920–1998), as the title of a research project to study severe weather in parts of Texas and Oklahoma.

Impact

Despite the elevated frequency of destructive tornadoes,

building code A building code (also building control or building regulations) is a set of rules that specify the standards for constructed objects such as buildings and non-building structures. Buildings must conform to the code to obtain planning permission ...

s, such as requiring strengthened roofs and more secure connections between the building and its

foundation Foundation may refer to: * Foundation (nonprofit), a type of charitable organization ** Foundation (United States law), a type of charitable organization in the U.S. ** Private foundation, a charitable organization that, while serving a good cause ...

, are not necessarily stricter compared to other areas of the United States and are markedly weaker than some hurricane prone areas, such as south Florida. One particular tornado-afflicted town,

Moore, Oklahoma Moore is a city in Cleveland County, Oklahoma, United States, and is part of the Oklahoma City metropolitan area. The population was 62,793 at the 2020 census, making Moore the seventh-largest city in the state of Oklahoma. Located between Oklah ...

, managed to increase its building requirements in 2014. Other common precautionary measures include the construction of

storm cellar A storm shelter or storm cellar is a type of underground bunker designed to protect the occupants from violent severe weather, particularly tornadoes. They are most frequently seen in the Midwest ("Tornado Alley") and Southeastern United States ( ...

s and the installation of tornado sirens. Tornado awareness,

preparedness Preparedness is a research-based set of actions that are taken as precautionary measures in the face of potential disasters. Preparedness is an important quality in achieving goals and in avoiding and mitigating negative outcomes. There are differ ...

, and

media Media may refer to: Communication * Media (communication), tools used to deliver information or data ** Advertising media, various media, content, buying and placement for advertising ** Broadcast media, communications delivered over mass e ...

weather coverage are also high. The southeastern United States is particularly prone to violent, long track tornadoes. Much of the housing in this region is less robust compared to other areas in the United States, and many people live in mobile homes. As a result, tornado-related casualties in the

southern United States The Southern United States (sometimes Dixie, also referred to as the Southern States, the American South, the Southland, or simply the South) is a geographic and cultural region of the United States of America. It is between the Atlantic Ocean ...

are higher. Significant tornadoes occur less frequently than in the traditionally recognized tornado alley; however, very severe and expansive

outbreaks In epidemiology, an outbreak is a sudden increase in occurrences of a disease when cases are in excess of normal expectancy for the location or season. It may affect a small and localized group or impact upon thousands of people across an entire ...

occur every few years.

Frequency of tornadoes

These figures, reported by the

for the period between 1991 and 2010, show the seventeen U.S. states with the highest average number of tornadoes per per year. # Florida: 12.3 # Kansas: 11.7 # Maryland: 9.9 # Illinois: 9.7 # Mississippi: 9.2 # Iowa: 9.1 # Oklahoma: 9 # South Carolina: 9 # Alabama: 8.6 # Louisiana: 8.5 # Arkansas: 7.5 # Nebraska: 7.4 # Missouri: 6.5 # North Carolina: 6.4 # Tennessee: 6.2 # Indiana: 6.1 # Texas: 5.9

Tornadoes in Canada

Canada gets the second most tornadoes in the world after the United States. The average number of tornadoes per equal area of land is highest in the southern parts of

Alberta Alberta ( ) is one of the thirteen provinces and territories of Canada. It is part of Western Canada and is one of the three prairie provinces. Alberta is bordered by British Columbia to the west, Saskatchewan to the east, the Northwest Ter ...

Saskatchewan Saskatchewan ( ; ) is a Provinces and territories of Canada, province in Western Canada, western Canada, bordered on the west by Alberta, on the north by the Northwest Territories, on the east by Manitoba, to the northeast by Nunavut, and on t ...

Manitoba Manitoba ( ) is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population o ...

, and

Ontario Ontario ( ; ) is one of the thirteen provinces and territories of Canada.Ontario is located in the geographic eastern half of Canada, but it has historically and politically been considered to be part of Central Canada. Located in Central Ca ...

Roughly half of all Canadian tornadoes strike the

and

Northern Ontario Northern Ontario is a primary geographic and quasi-administrative region of the Canadian province of Ontario, the other primary region being Southern Ontario. Most of the core geographic region is located on part of the Superior Geological Pro ...

as far east as

Lake Superior Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh wa ...

. Together, these regions make up the northernmost border of the U.S. Tornado Alley. Tornadoes up to EF5 in strength have been documented in this region. Another third of Canadian tornadoes strike

Southern Ontario Southern Ontario is a primary region of the province of Ontario, Canada, the other primary region being Northern Ontario. It is the most densely populated and southernmost region in Canada. The exact northern boundary of Southern Ontario is disp ...

and

Quebec Quebec ( ; )According to the Canadian government, ''Québec'' (with the acute accent) is the official name in Canadian French and ''Quebec'' (without the accent) is the province's official name in Canadian English is one of the thirtee ...

, especially in the region between the

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...

and the nation's capital city,

Ottawa Ottawa (, ; Canadian French: ) is the capital city of Canada. It is located at the confluence of the Ottawa River and the Rideau River in the southern portion of the province of Ontario. Ottawa borders Gatineau, Quebec, and forms the core ...

. Tornadoes do not often hit lake shadow regions, although they are not unknown, and some, such as the 2011 Goderich tornado, and the 2018 Ottawa tornadoes have been violent. However, most Ontario tornadoes are concentrated in a narrow corridor from

Windsor Windsor may refer to: Places Australia * Windsor, New South Wales ** Municipality of Windsor, a former local government area * Windsor, Queensland, a suburb of Brisbane, Queensland **Shire of Windsor, a former local government authority around Wi ...

as well as through portions of Central Quebec. Tornadoes up to F4 in strength have been documented in this region.

Southwestern Ontario Southwestern Ontario is a secondary region of Southern Ontario in the Canadian province of Ontario. It occupies most of the Ontario Peninsula bounded by Lake Huron, including Georgian Bay, to the north and northwest; the St. Clair River, Lake St. ...

weather is strongly influenced by its peninsular position between the

. As a result, increases in temperature in this region are likely to increase the amount of precipitation in storms due to lake evaporation. Increased temperature contrasts may also increase the violence and possibly the number of tornadoes.

between the Manitoba border and

is also prone to severe tornadoes, but tornadoes in this area are believed to be underestimated due to the extremely low population in this region.

References

External links

NSSL Tornado Climatology

Climatological Estimates of Local Daily Tornado Probability for the United States

Tornado hazards in the United States

Statistical modeling of tornado intensity distributions
{{U.S. Belt regions Tornado Regions of the United States Natural history of the United States

Geographical area

Origin of the term

Impact

Frequency of tornadoes

Tornadoes in Canada

See also

References

External links