"Tornado Alley" is, in the Storm Prediction Center's words, a nickname in the popular media for a broad swath of relatively high tornado occurrence in the central US, and maps of it differ because tornado occurrence can be measured in several ways. "Dixie Alley" is a similar nickname used for parts of the lower Mississippi and Tennessee valleys. Neither has official boundaries, so this page fixes its own: the Plains group is Texas, Oklahoma, Kansas, Nebraska, South Dakota, Iowa; the Dixie group is Arkansas, Louisiana, Mississippi, Alabama, Tennessee, Georgia. Whole states are a coarse unit — western Texas and eastern Georgia are a long way from either alley — but they are the unit the SPC database records.
Every figure below is counted from the SPC tornado database for 1950 onward, by the state SPC lists for each tornado.
| Measure | Plains (6 states) | Dixie (6 states) |
|---|---|---|
| Tornadoes since 1950 | 26,903 | 13,531 |
| Rated 3 or higher | 1,277 (4.7%) | 882 (6.5%) |
| Rated 4 or 5 | 254 (0.9%) | 159 (1.2%) |
| Deaths | 1,428 | 2,500 |
| Deaths per 100 tornadoes | 5.3 | 18.5 |
| Tornadoes that killed | 386 (1.4%) | 590 (4.4%) |
| Peak month | May | April |
| Share in April–June | 68% | 40% |
| Share in November–February | 6% | 31% |
| Tornadoes since 2000 | 10,624 | 7,321 |
| Deaths since 2000 | 272 | 979 |
How many, and how strong
The Plains group recorded 26,903 tornadoes and the Dixie group 13,531. Measured by share rather than count, 6.5% of Dixie tornadoes were rated 3 or higher against 4.7% in the Plains, and 1.2% against 0.9% were rated 4 or 5. Texas, with 9,610 tornadoes (the most of the twelve states), weighs heavily in its group's figures.
The deadlier group per tornado is the Dixie group: 18.5 deaths per 100 tornadoes in the Dixie states against 5.3 in the Plains, and 4.4% of Dixie tornadoes killed someone, against 1.4%. The database does not say why, and population, housing, terrain, trees and the time of day all differ between the regions; these are the counts, not an explanation of them. Put together, the Plains group holds 67% of the twelve states' tornadoes but 36% of their deaths; the Dixie group 33% of the tornadoes and 64% of the deaths.
The worst days
The deadliest single tornado in the Plains group struck Texas on May 11, 1953, rated F5, and killed 114; in the Dixie group, Alabama on April 27, 2011, rated EF5, killing 72. The Plains states have 28 tornadoes rated 5 on either scale, the Dixie states 13.
Since 2000 the Plains group has recorded 10,624 tornadoes with 272 deaths, and the Dixie group 7,321 with 979 deaths: 13.4 deaths per 100 tornadoes in the Dixie states against 2.6 in the Plains over the same years.
From 1950 to 1979 the figures were 10.6 deaths per 100 tornadoes in the Plains and 35.6 in the Dixie states, from 8,418 and 3,192 tornadoes. Both rates are lower since 2000, and part of the drop is arithmetic: far more weak tornadoes are recorded now, which lowers deaths per tornado whatever happened to safety.
Different seasons
The two groups peak at different times of year. In the Plains, May is the busiest month and 68% of tornadoes come between April and June. In the Dixie states the peak is April, the April–June share is 40%, and 31% come between November and February, against 6% in the Plains.
| Month | Plains | Dixie |
|---|---|---|
| January | 279 | 1,028 |
| February | 312 | 980 |
| March | 1,525 | 1,843 |
| April | 4,024 | 2,931 |
| May | 8,667 | 1,806 |
| June | 5,591 | 711 |
| July | 2,037 | 403 |
| August | 1,360 | 403 |
| September | 1,003 | 550 |
| October | 1,031 | 632 |
| November | 660 | 1,237 |
| December | 414 | 1,007 |
State by state
| State | Group | Tornadoes | Rated 3+ | Deaths |
|---|---|---|---|---|
| Texas | Plains | 9,610 | 401 | 609 |
| Kansas | Plains | 4,582 | 241 | 196 |
| Oklahoma | Plains | 4,484 | 268 | 452 |
| Nebraska | Plains | 3,203 | 131 | 56 |
| Iowa | Plains | 3,079 | 168 | 98 |
| Mississippi | Dixie | 2,854 | 195 | 505 |
| Alabama | Dixie | 2,681 | 186 | 679 |
| Louisiana | Dixie | 2,482 | 110 | 232 |
| Arkansas | Dixie | 2,090 | 183 | 415 |
| Georgia | Dixie | 1,977 | 85 | 237 |
| South Dakota | Plains | 1,945 | 68 | 17 |
| Tennessee | Dixie | 1,447 | 123 | 432 |
Each state page on this site ranks its cities by tornadoes within 25 miles. State totals here are not adjusted for area, so a large state collects more tornadoes simply by covering more ground. For warnings and shelter, see the National Weather Service's tornado safety pages.