Tornado outbreak sequence of May 21–26, 2011
From May 21 to May 26, 2011, several significant and deadly tornado outbreaks affected the Midwestern and Southern regions of the United States. A six-day tornado outbreak sequence, most of the tornadoes developed in a corridor from Lake Superior southwest to central Texas, while isolated tornadoes occurred in other areas.
Source: Wikipedia — Tornado outbreak sequence of May 21–26, 2011 (CC BY-SA 4.0)