From the HSDL, on April 26: 1 Year Anniversary of April 25-28, 2011 Tornado Outbreak. It was the 3rd most deadly tornado event in US history. Some details from the article:
Nearly one year ago today the third largest tornado outbreak in US history (since systematic tornado record keeping began in 1950) was recorded on April 25-28, 2011. The areas most affected by the devastating tornadoes included the Southern, Midwestern, and Northeastern United States. In particular, Alabama, Arkansas, Georgia, Mississippi, Tennessee, North Carolina and Virginia were hit hardest. According to a Department of Commerce Service Assessment report, more than 200 tornadoes occurred in the aforementioned states which resulted in 316 deaths, 2,400 injuries and over $4.2 billion in property damage. Out of the 200 tornadoes, 15 were considered to be EF4 to EF5 (Enhanced Fujita Scale 4 or 5) tornadoes. Note: The two deadliest tornado outbreaks ever recorded include the 1974 Super Tornado Outbreak (368 deaths) and the 1965 Palm Sunday Tornado Outbreak (337 deaths).