Dixie Alley

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Dixie Alley is a nickname sometimes given to areas of the southern United States that are particularly vulnerable to strong or violent tornadoes. [1] This is distinct from the better known Tornado Alley and has a high frequency of strong, long-track tornadoes that move at higher speeds (50+ miles per hour). The term was coined by NSSFC Director Allen Pearson after witnessing a tornado outbreak which included more than 9 long-track, violent tornadoes that killed 121 on February 21, 1971. [2] The specific characteristics of the Southeast led to VORTEX-SE, a field project studying tornadogenesis, diagnosis and forecasting, in addition to social science implications, and examines both supercellular tornadoes and those resulting from quasi-linear convective system (QLCS) thunderstorm structures. [3]

Southern United States Cultural region of the United States

The southern United States, also known as the American South, Dixie, or simply the South, is a region of the United States of America. It is located between the Atlantic Ocean and the western United States, with the midwestern United States and northeastern United States to its north and the Gulf of Mexico and Mexico to its south.

Tornado Violently rotating column of air that is in contact with both the earths surface and a cumulonimbus cloud in the air

A tornado is a rapidly 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. The windstorm 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 110 miles per hour (180 km/h), are about 250 feet (80 m) across, and travel a few miles before dissipating. The most extreme tornadoes can attain wind speeds of more than 300 miles per hour (480 km/h), are more than two miles (3 km) in diameter, and stay on the ground for dozens of miles.

Tornado Alley Area in the U.S. with frequent tornado outbreaks

Tornado Alley is a colloquial term for the area of the United States where tornadoes are most frequent.

Contents

Geography

The Dixie Alley region indicated by red shaded area. DixieAlleymap.png
The Dixie Alley region indicated by red shaded area.

Dixie Alley are is mostly in the lower Mississippi Valley. [4] It stretches from eastern Texas and Arkansas across Louisiana, Mississippi, Tennessee, Alabama, Georgia, to upstate South Carolina and western North Carolina; the area reaches as far north as southeast Missouri. [5] Another source places all of Arkansas within Dixie Alley. [6]

Texas State of the United States of America

Texas is the second largest state in the United States by both area and population. Geographically located in the South Central region of the country, Texas shares borders with the U.S. states of Louisiana to the east, Arkansas to the northeast, Oklahoma to the north, New Mexico to the west, and the Mexican states of Chihuahua, Coahuila, Nuevo León, and Tamaulipas to the southwest, and has a coastline with the Gulf of Mexico to the southeast.

Arkansas State of the United States of America

Arkansas is a state in the southern region of the United States, home to over 3 million people as of 2018. Its name is of Siouan derivation from the language of the Osage denoting their related kin, the Quapaw Indians. The state's diverse geography ranges from the mountainous regions of the Ozark and the Ouachita Mountains, which make up the U.S. Interior Highlands, to the densely forested land in the south known as the Arkansas Timberlands, to the eastern lowlands along the Mississippi River and the Arkansas Delta.

Louisiana State of the United States of America

Louisiana is a state in the Deep South region of the South Central United States. It is the 31st most extensive and the 25th most populous of the 50 United States. Louisiana is bordered by the state of Texas to the west, Arkansas to the north, Mississippi to the east, and the Gulf of Mexico to the south. A large part of its eastern boundary is demarcated by the Mississippi River. Louisiana is the only U.S. state with political subdivisions termed parishes, which are equivalent to counties. The state's capital is Baton Rouge, and its largest city is New Orleans.

Although tornadoes are less frequent in these states than they are in the southern Plains, the southeastern states have had more tornado-related deaths than any of the Plains states (excluding Texas). This is partly due to the fact that there are relatively high number of strong/violent long tracked tornadoes and higher population density of this region, as well as the Southern United States having the highest percentage of manufactured homes in the US, where 63% of the overall tornado-related fatalities occur. [7] According to the National Climatic Data Center, for the period January 1, 1950 October 31, 2006, Alabama and Kansas received the largest amount of F5 tornadoes. Complicating matters is that tornadoes are rarely visible in this area, as they are more likely to be rain-wrapped, embedded in shafts of heavy rain, and that the hilly topography and heavily forested landscape makes them difficult to see. [7]

National Climatic Data Center Active US archive of weather data.

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 Orleans, Louisiana in 1934, the climate records were transferred to Asheville in 1951, becoming named the National Weather Records Center (NWRC). It was later renamed the National Climatic Data Center, with relocation occurring in 1993. In 2015, it was merged with the National Geophysical Data Center (NGDC) and the National Oceanic Data Center (NODC) into the National Centers for Environmental Information (NCEI).

Kansas State of the United States of America

Kansas is a U.S. state in the Midwestern United States. Its capital is Topeka and its largest city is Wichita, with its most populated county being Johnson County. Kansas is bordered by Nebraska on the north; Missouri on the east; Oklahoma on the south; and Colorado on the west. Kansas is named after the Kansas River, which in turn was named after the Kansa Native Americans who lived along its banks. The tribe's name is often said to mean "people of the (south) wind" although this was probably not the term's original meaning. For thousands of years, what is now Kansas was home to numerous and diverse Native American tribes. Tribes in the eastern part of the state generally lived in villages along the river valleys. Tribes in the western part of the state were semi-nomadic and hunted large herds of bison.

The Fujita scale (F-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.

Prevalent tornado characteristics

Tornado in Mississippi, located in Dixie Alley, obscured by trees and featuring a notably low, rugged base. Tornado in Mississippi on December 23, 2015.jpg
Tornado in Mississippi, located in Dixie Alley, obscured by trees and featuring a notably low, rugged base.

Dixie Alley is part of a region of enhanced tornadic activity extending between the Appalachian and Rocky Mountains [8] , but tornadoes and outbreaks in the Dixie Alley region exhibit some statistically distinguishable characteristics than the more well known Tornado Alley. [9] 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. [7] [10] 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. [7] 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, [11] and several notorious outbreaks have struck during the late winter and early spring and also in late fall. [7] 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. [7]

Gulf of Mexico An Atlantic Ocean basin extending into southern North America

The Gulf of Mexico is an ocean basin and a marginal sea of the Atlantic Ocean, largely surrounded by the North American continent. It is bounded on the northeast, north and northwest by the Gulf Coast of the United States, on the southwest and south by Mexico, and on the southeast by Cuba. The U.S. states of Texas, Louisiana, Mississippi, Alabama, and Florida border the Gulf on the north, which are often referred to as the "Third Coast", in comparison with the U.S. Atlantic and Pacific coasts.

Storm spotting is a form of weather spotting in which observers watch for the approach of severe weather, monitor its development and progression, and actively relay their findings to local authorities.

Storm chasing Pursuit of any severe weather condition

Storm chasing is broadly defined as the pursuit of any severe weather condition, regardless of motive, which can be curiosity, adventure, scientific investigation, or for news or media coverage.

A 2018 study found in the U.S. an overall eastward shift of tornado frequency and impacts toward Dixie Alley. [12] The study found relatively-lower tornado frequency and impacts in parts of the traditional Tornado Alley, especially areas from north-central Texas toward the Houston, Texas area, and relatively-higher tornado frequency and impacts in parts of the Mid-South, especially eastern Arkansas, the greater Memphis, Tennessee area and northern Mississippi all areas near the heart of Dixie Alley (see especially Figure 4). [13]

Mid-South (region)

The Mid-South is an informally-defined region of the United States, usually thought to be anchored by the Memphis metropolitan area and consisting of West Tennessee, North Mississippi, Southern Missouri, Western Kentucky, Central, Northeast, and Northwest Arkansas, and Northwest Alabama. Southern Illinois is sometimes included in this region. In the south region itself there are 16 states.

Memphis, Tennessee City in Tennessee, United States

Memphis is a city located along the Mississippi River in southwestern Shelby County, Tennessee, United States. The 2017 city population was 652,236, making Memphis the largest city on the Mississippi River, the second most populous city in Tennessee, as well as the 25th largest city in the United States. Greater Memphis is the 42nd largest metropolitan area in the United States, with a population of 1,348,260 in 2017. The city is the anchor of West Tennessee and the greater Mid-South region, which includes portions of neighboring Arkansas and Mississippi. Memphis is the seat of Shelby County, the most populous county in Tennessee. As one of the most historic and cultural cities of the southern United States, the city features a wide variety of landscapes and distinct neighborhoods.

Variations in climate patterns and teleconnections, such as the El Niño–Southern Oscillation (ENSO) can also have significant impacts on tornadic activity in the region from year to year. Climate change is also expected to affect tornado activity in the region. [14] [15]

A climate pattern is any recurring characteristic of the climate. Climate patterns can last tens of thousands of years, like the glacial and interglacial periods within ice ages, or repeat each year, like monsoons.

Teleconnection in atmospheric science refers to climate anomalies being related to each other at large distances. The most emblematic teleconnection is that linking sea-level pressure at Tahiti and Darwin, Australia, which defines the Southern Oscillation.

El Niño–Southern Oscillation Irregularly periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean

El Niño–Southern Oscillation (ENSO) is an irregularly periodic variation in winds and sea surface temperatures over the tropical eastern Pacific Ocean, affecting the climate of much of the tropics and subtropics. The warming phase of the sea temperature is known as El Niño and the cooling phase as La Niña. The Southern Oscillation is the accompanying atmospheric component, coupled with the sea temperature change: El Niño is accompanied by high air surface pressure in the tropical western Pacific and La Niña with low air surface pressure there. The two periods last several months each and typically occur every few years with varying intensity per period.

Notable outbreaks

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. [7] 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. [16]

See also

Related Research Articles

Supercell thunderstorm that is characterized by the presence of a mesocyclone

A supercell is a thunderstorm characterized by the presence of a mesocyclone: a deep, persistently rotating updraft. For this reason, these storms are sometimes referred to as rotating thunderstorms. Of the four classifications of thunderstorms, supercells are the overall least common and have the potential to be the most severe. Supercells are often isolated from other thunderstorms, and can dominate the local weather up to 32 kilometres (20 mi) away. They tend to last 2-4 hours.

1974 Super Outbreak April 1974, the 2nd-largest tornado outbreak ever in a 24-hour period

The 1974 Super Outbreak was the second-largest tornado outbreak on record for a single 24-hour period, just behind the 2011 Super Outbreak. It was also the most violent tornado outbreak ever recorded, with 30 F4/F5 tornadoes confirmed. From April 3 to 4, 1974, there were 148 tornadoes confirmed in 13 U.S. states and the Canadian province of Ontario. In the United States, tornadoes struck Illinois, Indiana, Michigan, Ohio, Kentucky, Tennessee, Alabama, Mississippi, Georgia, North Carolina, Virginia, West Virginia, and New York. The outbreak caused roughly $843 million USD with more than $600 million in damage occurring in the United States. The outbreak extensively damaged approximately 900 sq mi (2,331 km2) along a total combined path length of 2,600 mi (4,184 km). At one point, as many as 15 separate tornadoes were on the ground simultaneously.

Tornado outbreak of April 15–16, 1998

The April 15–16, 1998 tornado outbreak was a two-day tornado outbreak that affected portions of the Midwestern United States, Mississippi and Tennessee Valleys on April 15 and April 16, 1998, with the worst of the outbreak taking place on the second day. On that day, 13 tornadoes swept through Middle Tennessee—two of them touching down in Nashville, causing significant damage to the downtown and East Nashville areas. Nashville became the first major city in nearly 20 years to have an F2 or larger tornado make a direct hit in the downtown area.

Tornado climatology

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. 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. Canada experiences the second most tornadoes with the provinces of Ontario, Saskatchewan, Manitoba, and Alberta seeing the highest frequency, particularly with southward extent. 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.

Tornado outbreak of November 23–24, 2001

The Tornado outbreak of November 23–24, 2001 was a fall tornado outbreak which affected portions of the southern United States from Arkansas to Alabama on November 23–24, 2001, with additional tornadoes recorded in Louisiana, Kentucky, Missouri, Indiana and Georgia. Recorded as one of the most intense November outbreaks ever across that area, tornadoes from the event killed at least 13 across three states including 4 in Alabama, four in Arkansas and five in Mississippi.

The Hurricane Ivan tornado outbreak was a three-day tornado outbreak that was associated with the passage of Hurricane Ivan across the Southern United States starting on September 15, 2004 across the Gulf Coast states of Alabama and Florida as well as southern Georgia before ending in the Middle Atlantic Coast on September 18.

Tornadoes in the United States

Tornadoes are more common in the United States than in any other country. 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 late-April 1909 tornado outbreak was a deadly tornado outbreak that affected much of the central and Southern United States between April 29 and May 1, 1909. Affecting particularly the Mississippi and Tennessee Valleys, it killed over 150 people, 60 of them in the U.S. state of Tennessee alone. It was the deadliest known tornado outbreak to affect Tennessee until March 21, 1952, when 64 people died statewide. To this day, the 1909 outbreak remains the second-deadliest on record in Tennessee—even the April 3–4, 1974 Super Outbreak and the February 5–6, 2008, Super Tuesday outbreak produced just 45 and 31 deaths each in the state.

Tornadoes of 1998

This page documents the tornadoes and tornado outbreaks of 1998, primarily in the United States. Most tornadoes form in the U.S., although some events may take place internationally. Tornado statistics for older years like this often appear significantly lower than modern years due to fewer reports or confirmed tornadoes, however by the 1990s tornado statistics were coming closer to the numbers we see today.

Tornadoes of 2011 Wikimedia list article

This page documents the tornadoes and tornado outbreaks of 2011. Extremely 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.

2010 New Years Eve tornado outbreak

The 2010 New Year's Eve tornado outbreak was a three-day-long tornado outbreak that impacted the central and lower Mississippi Valley from December 30, 2010 to January 1, 2011. Associated with a low pressure system and a strong cold front, 37 tornadoes tracked across five states over the length of the severe event, killing nine and injuring several others. Activity was centered in the states of Missouri and later Mississippi on December 31. Seven tornadoes were rated EF3 on the Enhanced Fujita Scale; these were the strongest during the outbreak. Non-tornadic winds were recorded to have reached as high as 80 mph (130 km/h) at eight locations on December 31, while hail as large as 2.75 in (7.0 cm) was documented north-northeast of Mansfield, Missouri. Overall, damage from the outbreak totaled US$123.3 million, most of which was related to tornadoes.

Tornado outbreak of April 14–16, 2011

The tornado outbreak of April 14–16, 2011 was among the largest recorded tornado outbreaks in U.S. history, producing 178 confirmed tornadoes across 16 states and severe destruction on all three days of the outbreak. A total of 38 people were killed from tornadoes and an additional five people were killed as a result of straight-line winds associated with the storm system. The outbreak of severe weather and tornadoes led to 43 deaths in the Southern United States. This was the largest number of fatalities in an outbreak in the United States since the 2008 Super Tuesday tornado outbreak. However, this outbreak was soon surpassed no less than two weeks later by the 2011 Super Outbreak, which killed 324 people.

2011 Super Outbreak Extremely large tornado outbreak

The 2011 Super Outbreak was the largest, costliest, and one of the deadliest tornado outbreaks ever recorded, taking place along the Southern, Midwestern, and Northeastern United States and leaving catastrophic destruction in its wake. The event not only affected Alabama and Mississippi the most severely, but also produced destructive tornadoes in Arkansas, Georgia, Tennessee and Virginia, and affected many other areas throughout 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, with April 27 being the most active day with a record of 216 tornadoes touching down that day from midnight to midnight CDT. Four of the tornadoes were destructive enough to be rated EF5, which is the highest ranking possible on the Enhanced Fujita scale; typically these tornadoes are only recorded about once each year or less.

Tornadoes of 2012 Tornadoes that occurred in 2012.

This page documents the tornadoes and tornado outbreaks of 2012. Extremely destructive tornadoes form most frequently in the U.S., 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, Argentina, and Australia.

Tornado outbreak sequence of March 18–24, 2012

The Tornado outbreak sequence of March 18–24, 2012 was a long lasting tornado outbreak that occurred due to a slow moving, but powerful trough and cutoff low. The outbreak began in the Great Plains, where, over a two-day period, several tornadoes touched down, some of which were significant. The North Platte area was damaged by an EF3 that was produced by a supercell that spawned many tornadoes throughout its lifespan. The tornadic activity then shifted the Southern United States over subsequent days, particularly in Louisiana and Mississippi. These states were struck by a series of tornadoes for 3 days, most of which were relatively weak on the Enhanced Fujita Scale. However, a few reached EF2 intensity and caused considerable damage. Tornado activity continued across the Ohio Valley on the 23rd, with one confirmed fatality in southern Illinois.

December 2015 North American storm complex

The December 2015 North American storm complex was a major storm complex that produced a tornado outbreak, a winter storm, a blizzard and an ice storm in areas ranging from the Southwestern United States to New England. Tornadoes impacted areas around Dallas, Texas. Several states, especially Missouri, were affected by heavy rain and snow causing severe floods. As the system moved through the Great Lakes region, heavy rain, ice pellets and heavy snow fell in the entire region. Wintry mix moved through southern Ontario and Quebec had significant snowfall on December 29. Almost 60 people were killed in the storm system and its aftermath, which made it one of the deadliest of such systems of 2015 in the United States.

The Tornado outbreak of April 2–3, 1982 was a major tornado outbreak that resulted in over sixty tornadoes and 29 fatalities. Three tornadoes were rated F4, and one officially was recorded as an F5 near Broken Bow, Oklahoma, all on April 2nd. The F5 resulted in no fatalities, but an F4 tornado in Paris, Texas resulted in 10 fatalities and 170 injuries.

2011 Philadelphia, Mississippi tornado

During the afternoon of Wednesday, April 27, 2011, a violent EF5 tornado touched down in eastern Mississippi, killing three people. Part of the historic 2011 Super Outbreak, the largest tornado outbreak on record, this was the first of four EF5 tornadoes to touch down that day and the first such storm in Mississippi since the 1966 Candlestick Park tornado. While on the ground for 30 minutes, it traveled along a near 29-mile (47 km) path through four counties, leaving behind three deaths, eight injuries, and $1.1 million in damage.

2011 Smithville, Mississippi tornado

On Wednesday, April 27, 2011, an extremely violent EF5 wedge tornado, with estimated winds of up to 205 mph (330 km/h), struck the town of Smithville, Mississippi at 3:47 p.m. CDT on April 27, resulting in catastrophic damage and numerous fatalities.

References

  1. Cox, John D. (April 27, 2010). "Redefining Tornado Alleys". Discovery Channel . Retrieved March 1, 2012.
  2. Rice, Doyle (April 26, 2011). "Dixie Alley may see more tornado action than even Tornado Alley". USA Today . Retrieved March 1, 2012.
  3. VORTEX Southeast
  4. Douglas, Paul (April 28, 2010). "Deadlier than Tornado Alley: "Dixie Alley"". Star Tribune . Retrieved March 1, 2012.
  5. "New study puts metro Atlanta in 'Dixie Alley' for tornadoes". Atlanta Journal-Constitution. April 28, 2010. Retrieved March 1, 2012.
  6. Wind Design (Technical report). FM Global. October 2016. p. 97. Data Sheet 1-28.
  7. 1 2 3 4 5 6 7 Hayes, John L. (March 2009). "Service Assessment on the Super Tuesday Tornado Outbreak of February 5-6, 2008" (PDF). NOAA . Retrieved March 1, 2012.
  8. Dixon, P. Grady; A. E. Mercer; J. Choi; J. S. Allen (2011). "Tornado Risk Analysis: Is Dixie Alley an Extension of Tornado Alley?". Bull. Amer. Meteor. Soc. 92 (4): 433–441. doi:10.1175/2010BAMS3102.1.
  9. Gagan, John P.; A. Gerard; J. Gordon (2010). "A Historical and Statistical Comparison of "Tornado Alley" to "Dixie Alley"" (PDF). NWA Digest. 13 (2): 145–155.
  10. "Safety Helmets: A Practical, Inexpensive Solution for Reducing the Risk of Head Injuries Resulting from Tornadoes". University of Alabama Birmingham. Retrieved February 23, 2012.
  11. Saslow, Rachel (April 28, 2011). "Tornado season is at its height in 'Dixie Alley'". The Washington Post. Retrieved March 1, 2012.
  12. https://www.usatoday.com/story/weather/2018/10/17/tornado-alley-shifting-east/1660803002/
  13. https://www.nature.com/articles/s41612-018-0048-2
  14. Strader, Stephen M.; W. S. Ashley; T. J. Pingel; A. J. Krmenec (2017). "Projected 21st century changes in tornado exposure, risk, and disaster potential". Climatic Change. 141 (2): 301–313. doi:10.1007/s10584-017-1905-4.
  15. Strader, Stephen M.; W. S. Ashley; T. J. Pingel; A. J. Krmenec (2017). "Observed and Projected Changes in United States Tornado Exposure". Wea. Climate Soc. 9 (2): 109–123. doi:10.1175/WCAS-D-16-0041.1.
  16. "April 2011 tornado information". NOAA . USA.gov. May 9, 2011. Retrieved May 16, 2011.