Despite Sunday's destruction, 2013 has been a relatively mild year for twisters in the U.S., with the number of tornadoes running at or near record lows.
So far this year, there have been 886 preliminary reports of tornadoes, compared with about 1,400 preliminary reports usually sent to the weather service by mid-November.
Similar slow years were 1987 and 1989.
An outbreak like the one that developed Sunday usually happens about once every seven to 10 years, according to tornado experts at the National Weather Service's Storm Prediction Center in Norman, Okla.
There were similar November outbreaks in 1992 and 2002, with the 1992 one being even bigger than this year's, said top tornado researcher Harold Brooks at the National Severe Storms Laboratory, also in Norman.