Tornado outbreak of May 10–12, 2014
From May 10–12, 2014, a large and widespread tornado outbreak of 44 tornadoes spanned across portions of the central and Great Plains regions of the United States. The May 11 portion is sometimes referred to as the Mother's Day tornado outbreak by locals, due to it occurring on the celebration at the time.
Source: Wikipedia — Tornado outbreak of May 10–12, 2014 (CC BY-SA 4.0)