Instruct: Given a question, retrieve documents that can help answer the question.
Query: What states are included in Tornado Alley?
The term was first used in 1952 as the title of a research project to study severe weather in areas of Texas, Oklahoma, Kansas, South Dakota, Iowa, Missouri, Nebraska, Colorado, North Dakota, and Minnesota. It is largely a media-driven term although tornado climatologists distinguish peaks in activity in certain areas[2] and storm chasers have long recognized the Great Plains tornado belt.[3]
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 (NWS).[6] Thus, differences in location are the result of the different criteria used.[6][7]
Tornadoes occur frequently in Alabama during the spring and fall months, these tornadoes can be devastating and even deadly.– these are common throughout the state, although the peak season for tornadoes varies from the northern to southern parts of the state. Alabama, along with Kansas, has the most reported F5/EF5 tornadoes than any other state – according to statistics from the National Climatic Data Center for the period January 1, 1950, to October 31, 2006. An F5 tornado is the most powerful of its kind. Several long – tracked F5 tornadoes have contributed to Alabama reporting more tornado fatalities than any other state except for Texas and Mississippi. The Super Outbreaks of April 1974 and April 2011 both badly affected Alabama. The northern part of the state – along the Tennessee Valley – is one of the areas in the US most vulnerable to violent tornadoes . The area of Alabama and Mississippi most affected by tornadoes is sometimes referred to as Dixie Alley, as distinct from the Tornado Alley of the Southern Plains. Alabama is one of the few places in the world that has a secondary tornado season (November and December) along with the spring severe weather season.
Located in Tornado Alley, many tornadoes have struck the county, including an F4 tornado on April 10, 1979, which obliterated the town of Braddyville, Iowa across the county line. Tornadoes have damaged two of the county's largest buildings, the Administration Building on the campus of Northwest Missouri State University and Conception Abbey. The 1881 Hopkins tornado is one of the first recorded F5 tornadoes.
Argentina experiences frequent tornados each year. Tornados occur in the South American "tornado alley" ("Spanish: Pasillo de los Tornados"), which includes the provinces of Entre Ríos, Córdoba Province, Santa Fe, La Pampa and Greater Buenos Aires. The frequency of tornadoes is similar to the one found in Tornado Alley in North America. However, there is no exact number of tornado occurrences per year, owing to the lack of data. These regions have the most frequent and intense mesoscale convective systems. Tornados occur between November and April. In this region, which occupies most of the Pampas, cold air from Patagonia meets warm, humid air from Brazil with dry air coming from the Andes. When these air masses collide, they can produce intense storms, frequently becoming supercells that can produce tornados. With a larger number of convective storms, there is a higher chance that some of these storms will produce tornados. Most tornados are relatively weak and rarely cause deaths. The strongest tornado recorded in Argentina occurred in 1973 when a tornado struck San Justo, Santa Fe. The tornado was an F5 on the Fujita scale, with winds up to , making it the worst tornado in Latin America and the Caribbean.
Another criterion for the location of Tornado Alley (or Tornado Alleys) can be where the strongest tornadoes occur more frequently.[11]
Tornadoes have been recorded on all continents except Antarctica and are most common in the middle latitudes where conditions are often favorable for convective storm development.[1] The United States has the most tornadoes of any country, as well as the strongest and most violent tornadoes. A large portion of these tornadoes form in an area of the central United States popularly known as Tornado Alley.[2] Other areas of the world that have frequent tornadoes include significant portions of Europe, South Africa, Philippines, Bangladesh, parts of Argentina, Uruguay, and southern and southeast Brazil, northern Mexico, New Zealand, and far eastern Asia.[3][4]
No state is entirely free of tornadoes; however, they occur more frequently in the Central United States, between the Rocky Mountains and Appalachian Mountains.[6] Texas reports the most tornadoes of any state due to its large size, in addition to its proximity to Tornado Alley. Kansas and Oklahoma ranked first and second respectively in the number of tornadoes per area, per data collected through 2007, however in 2013 statistics from the National Climatic Data Center show Florida ranked first.[20] Although Florida reports a high number and density of tornado occurrences, tornadoes there rarely reach the strength of those that sometimes occur in the southern plains.[10] Regionally, the frequency of tornadoes in the United States is closely tied with the progression of the warm season when warm and cold air masses often clash.[10]
Illinois averages approximately 51 days of thunderstorm activity a year, which ranks somewhat above average in the number of thunderstorm days for the United States. Illinois is vulnerable to tornadoes, with an average of 35 occurring annually, which puts much of the state at around five tornadoes per annually. While tornadoes are no more powerful in Illinois than other states, some of Tornado Alley's deadliest tornadoes on record have occurred in the state. The Tri-State Tornado of 1925 killed 695 people in three states; 613 of the victims died in Illinois. Other significant high-casualty tornadoes include the 1896 St. Louis – East St. Louis tornado, which killed 111 people in East St. Louis and a May 1917 tornado that killed 101 people in Charleston and Mattoon. Modern developments in storm forecasting and tracking have caused death tolls from tornadoes to decline dramatically, with the 1967 Belvidere – Oak Lawn – Chicago South Side tornado outbreak (58 fatalities) and 1990 Plainfield tornado (29 fatalities) standing out as exceptions. On November 17, 2013, an EF4 tornado touched down and ripped through Washington, Illinois. There were three fatalities.
The following is a list of 2009 Minnesota tornadoes. Minnesota is a state located in the North Central United States along the northern edge of Tornado Alley, and on average receives 24 tornadoes per year. 2009 was an average year historically, with 24 confirmed tornado touchdowns. Twenty-two of the tornadoes (91%) were considered "minor", rated EF0 or EF1 on the Enhanced Fujita scale. The remaining two tornadoes were rated as "significant", at EF2.
The Midwestern states are very prone to tornado activity, as they are part of "Tornado Alley." States included in the area that are hit by tornadoes the most are Oklahoma, Kansas, Missouri, Nebraska, Iowa, and South Dakota. The Midwestern States are often hit by tornadoes during the late spring and early summer months, especially the months of May and June. This is due to the aforementioned air mass moving northward into the Midwest and combining with another air mass that move southward from Canada. This creates unstable air, creating the potential for storms to strike the most during these months. The frequency begins to decrease in the middle of the summer, as the air mass moves northward into the Great Lakes states.
There were no building codes requiring tornado shelters nor specifically designed to prevent tornado damage until the 2011 Joplin tornado prompted a local ordinance requiring hurricane ties or similar fasteners. The state of Oklahoma adopted the minimum U.S. standard that year for the first time, but did not add high-wind protections like those in Florida designed to protect against hurricanes. Other states in Tornado Alley have no statewide building codes. The chance of any given location in Tornado Alley getting hit by an F-2 tornado (strong enough to do major structural damage and exceeding the 90 mph guideline for straightline winds) is about 1 every 4,000-5,000 years; in other areas the annual probability is one in several million. The most stringent building codes only require earthquake strengthening for a 1 in every 500-1,000 year probability.
Although the official boundaries of the Canadian Tornado Alleys are not clearly defined, its core extends from Central Alberta through Saskatchewan, Southern Manitoba and Northwestern Ontario. A second tornado alley extends from Michigan to Central Ontario and from Central Ontario to Southwestern Quebec. The Canadian Prairies are often considered part of the United States tornado alley.
Although the official boundaries of Tornado Alley are not clearly defined, its core extends from northern Texas, Oklahoma, Kansas, Nebraska, into South Dakota. States such as Missouri, Iowa, Minnesota, Wisconsin, Illinois, Indiana, and western Ohio are sometimes included in Tornado Alley.[4] Some research suggests that tornadoes are becoming more frequent in the northern parts of Tornado Alley where it reaches the Canadian prairies.[9]
The Canadian Tornado Alley(s) is a term describing a tornado-prone region in Canada. In Canada, the word is rarely used when compared to that of the United States where their "Tornado Alley" is largely a media-driven term.
It has also been asserted that there are numerous Tornado Alleys.[4] In addition to the Texas/Oklahoma/Kansas core, such areas include the Upper Midwest, the lower Ohio Valley, the Tennessee Valley and the lower Mississippi valley.[4] Some studies suggest that there are also smaller tornado alleys located across the United States.[2]
Canada Tornado Alley Dixie Alley Hailstorm Alley Hurricane Alley List of tornadoes and tornado outbreaks List of tornadoes by calendar day Tornado climatology
Tornado Alley is a colloquial term for the area of the United States where tornadoes are most frequent.[1]
Dixie Alley has been subject to numerous tornado outbreaks throughout history, including very intense outbreaks and those of very large spatial and temporal extent. Notorious outbreaks affecting the region include: the Great Natchez Tornado, the 1884 Enigma tornado outbreak, the April 1924 tornado outbreak, the 1932 Deep South tornado outbreak, the 1936 Tupelo-Gainesville tornado outbreak, the April 1957 Southeastern tornado outbreak, the 1984 Carolinas tornado outbreak, and the November 1992 tornado outbreak. The 1974 Super Outbreak also hit the area very hard, producing multiple F5 tornadoes in Alabama, and F4 tornadoes in North Georgia and the Appalachian southwest of North Carolina. More recently the region was hit by the 2008 Super Tuesday tornado outbreak followed by the tornado outbreak of April 14–16, 2011, the deadliest since the 2008 outbreak. Two weeks after the April 14–16 event, Dixie Alley was the epicenter of the 2011 Super Outbreak, which was the largest tornado outbreak ever recorded, as well as the fourth-deadliest outbreak in United States history, with over 300 people dead.
According to the Köppen Climate Classification system, Estelline has a semi-arid climate, abbreviated "BSk" on climate maps.
Estelline, Texas is often referred to as being located at the core of Tornado Alley. Over the years, the location(s) of Tornado Alley have not been clearly defined. No official definition of 'tornado alley' or the geographical area of tornado alley has ever been designated by the National Weather Service Thus, differences of location are the result of the different criteria used.
Dixie Alley is part of a region of enhanced tornadic activity extending between the Appalachian and Rocky Mountains, but tornadoes and outbreaks in the Dixie Alley region exhibit some statistically distinguishable characteristics than the more well known Tornado Alley. Tornadic storms in Dixie Alley are most often high precipitation supercells due to an increase of moisture from proximity to the nearby Gulf of Mexico. The Dixie Alley tornadoes accompanying the HP supercells are often partially or fully wrapped in rain visually impairing the tornadoes to storm spotters and chasers, law enforcement, and the public. Increases of warmth and instability in conjunction with strong wind shear in the Dixie Alley region impacts the times when tornadoes form. In the traditional Tornado Alley, tornadoes most often form from the mid afternoon to early evening. Dixie Alley's instability can be maintained long after sunset due to being adjacent to the Gulf, increasing the frequency of intense nighttime and early morning tornadoes. There is also a less focused tornado season which tends to be most active in early spring and late autumn but can continue throughout the winter and into late spring, which can lead to complacency among residents of the region. The region often is subject to tornadoes much earlier than the general national peak from May and June, usually from February to Mid-April, and several notorious outbreaks have struck during the late winter and early spring and also in late fall. The complacency situation was noted after the 2008 Super Tuesday tornado outbreak in February 2008 that hit the Dixie Alley killing 57 people, many people indicated that they had underestimated the threat of severe weather on that day since it was well before the peak of tornado season. 
According to the National Severe Storms Laboratory (NSSL) FAQ,[6] "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.[8]
States such as Missouri, Iowa, Minnesota, Wisconsin, Illinois, Indiana, and western Ohio are sometimes included in Tornado Alley.[4] Research suggests that tornadoes are becoming more frequent in the northern parts of Tornado Alley where it reaches the Canadian prairies.[5]
Over the years, the location(s) of the Canadian Tornado Alley(s) have been better defined. No complete definition of Canadian Tornado Alley has ever been officially designated and announced by the Environment and Climate Change Canada (ECCC). 
The following is a list of 2008 Minnesota tornadoes. Minnesota is a state located in the North Central United States along the northern edge of Tornado Alley, and on average receives 24 tornadoes per year. 2008 was a more active year historically, with 43 confirmed tornado touchdowns. Thirty-eight of the tornadoes (or 88%) were considered "minor", rated EF0 or EF1 on the Enhanced Fujita scale. The remaining five tornadoes were rated as "significant", at EF2 or EF3.