April period witnessed the largest tornado outbreak in world history.  May period includes two of the costliest tornadoes ever recorded.

Yes, it was really THAT bad – 3 times the average of losses for the 20 year period of 1990-2010!  Severe weather losses are estimated at $15B according to the Aon Benfield report, United States April and May 2011 Severe Weather Outbreaks,  published by Impact Forecasting.  The late-April period witnessed the largest tornado outbreak in world history, comprising 334 separate tornado touchdowns which led to catastrophic damage throughout the Southeast and the Tennessee Valley.

Steve Jakubowski, President of Impact Forecasting, said: “”The late-May stretch was highlighted by an outbreak that spawned a massive EF-5 tornado that destroyed a large section of Joplin, Missouri. The tornado led to 154 fatalities in the city, becoming the deadliest singular tornadic event since the National Weather Service officially began keeping records in 1950. In addition, it is worth noting that the Tuscaloosa and Joplin events will go down as two of the costliest singular tornadoes ever recorded.”

The report examines the active stretch of severe weather that occurred across areas east of the Rocky Mountains, where at least eight separate timeframes saw widespread severe weather activity – including five separate outbreaks with losses in excess of one billion dollars (USD).  Of the eight timeframes examined in this report, the two most notable stretches occurred between April 22-28 and May 21-27.   To read the complete News Release with a link to the full report… Read more. 

Source:  News Release, Aon Benfield – June 22, 2011