Killer Twisters Likely Among Largest, Strongest

ABC News - Chris Weiss, a tornado expert at Texas Tech University, said the storm that spawned that tornado formed in Mississippi and 'lasted over 300 miles, and even for a super cell that's pretty long.'

Some of the killer tornadoes that ripped across the South may have been among the largest and most powerful ever recorded, experts suggested, leaving a death toll that is approaching that of a tragic "super outbreak" of storms almost 40 years ago.

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Chris Weiss, a tornado expert at Texas Tech University, said the storm that spawned that tornado formed in Mississippi and "lasted over 300 miles, and even for a super cell that's pretty long."

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