Tornadoes in Alabama

The U.S. state of Alabama has seen numerous destructive and devastating tornadoes since 1819, the year with the first recorded tornado within state boundaries. Alabama, located in the "Dixie Alley" region of the Southern United States, experiences an average of 64 tornadoes annually.^[1] 297 tornadoes have been classified as "intense" in Alabama, being rated F3+ on the Fujita scale^{[note 1]} or EF3+ on the Enhanced Fujita scale. Alabama has seen nine F5 or EF5 tornadoes since 1966, the most recent hitting Rainsville in April 2011. The deadliest moved across North Alabama, hitting numerous communities and killing 71 people.

Alabama saw numerous significant tornadoes prior to 1950, including an F4 tornado that killed 30 people in Calhoun and Cherokee counties. 1932 saw a devastating tornado outbreak that killed over 200 people in the state of Alabama; an F4-rated tornado impacted the cities of Tuscaloosa and Northport. 26 people were killed in 1935 when a strong tornado moved through the city of Montgomery. The 1950s were saw several large and destructive tornadoes impact communities. The widest of the decade, rated F3, reached a maximum width of 1480 yd (1350 m) as it moved across Russell County. In 1954, a violent tornado took the lives of 25 people in the northern suburbs of Birmingham; another tornado just eight days earlier killed five people in Falkville.

Tornadoes in the 1960s were equally-as-destructive, with a total of 157 tornadoes touching down within state boundaries, killing 81 people. An extremely long-tracked F5 tornado that originated in Mississippi moved into Alabama on March 3, 1966; Tuscaloosa and other communities were affected. Earlier in the decade an F4 tornado killed 10 people and injured six others southeast of Harpersville.

The 1970s was a highly-deadly decade for tornadoes in Alabama, with the "Super Outbreak" occurring in 1974. Alabama was affected by three F5 tornadoes that day, with at least 78 people dying in the state. The town of Tanner saw two destructive F5 tornadoes that each killed over 15 people. Later in the decade saw an F5 tornado impact the suburbs of Birmingham, Alabama, killing 22. Only 36 people were killed by tornadoes through the 1980s, most of which were from a destructive tornado that moved through areas near Huntsville in November 1989.

The 1990s were a relatively significant decade for tornadoes in Alabama. On March 27, 1994, an F4 tornado killed 22 people in the Piedmont area; an F3 tornado near Fyffe on the same day injured 20 others. Six people were killed when a tornado moved south of Arab on February 15, 1995. The end of the decade saw an F5 tornado devastate portions of northern Birmingham, killing 32 and injuring over 200 others.

The 2000s were quiet in terms of tornado activity in Alabama, with the deadliest tornado killing 11 people on December 16, 2000. Several F4 tornadoes hit the state during this period, including one that moved through the city of Enterprise. The 2010s saw the most destructive tornado outbreak in recorded history on April 27, 2011; Alabama was impacted by 62 tornadoes.^[4] Several violent tornadoes affected communities across the state like Cordova, Tuscaloosa, Birmingham, Hackleburg, Phil Campbell, Oak Grove, Plainview, Cullman, Fackler, Flat Rock, Eoline and other communities in North and Central Alabama. The outbreak killed an estimated 247 persons in Alabama alone, making it the second-deadliest tornado outbreak in the state's history.^[5] Both the deadliest and widest tornadoes in Alabama history occurred on this day.

Alabama is located in a region known informally as "Dixie Alley", a term used for areas of the southern United States which are particularly vulnerable to strong to violent tornadoes.^[6] Dixie Alley is part of a region of enhanced tornadic activity extending between the Appalachian and Rocky Mountains,^[7] but tornadoes and outbreaks in the Dixie Alley region exhibit some statistically distinguishable characteristics from the more well known Tornado Alley.^[8] 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, impairing the visibility of the tornadoes to storm spotters and chasers, law enforcement, and the public.^[9][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.^[9][10]

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.^[9] 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.^[9]

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 numbers 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.^[12] According to the National Climatic Data Center (NCDC), for the period January 1, 1950 – October 31, 2006, Alabama and Kansas received the largest number 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.^[12]

• Tornadoes in Oklahoma