Comparing the Worst Outbreaks
There are many ways to compare tornado outbreaks. You can simply look at raw tornado or fatality counts for a quick look. But how do you truly dig down to answer the question, "Which are the worst U.S. tornado outbreaks?"
These parameters include not only deaths and tornado counts, but also number of violent tornadoes, killer tornadoes, damage amounts, total tornado path length, number of wide-track tornadoes, number of states affected, number of tornadoes per hour and number of injuries.
These values were combined into a "Forbes Impact Index", with a maximum value of 100.
To be clear, we are considering tornado outbreaks, not necessarily one singular, destructive tornado, such as, for example, Greensburg, Kan. (May 2007).