The most extreme tornadoes have winds over 200 mph and can measure over a mile wide, and it has been over a decade since the ...

Researches found little evidence that tornadoes were getting weaker. Instead, it appears that a subjective tornado grading system is to blame.

Hundreds of homes vanished beneath the black cloud that descended on May 20, 2013. The violent tornado that forever scarred Moore ... Both scales range from F0/EF-0 (“weak”) to F5/EF-5 (“incredible”), ...

Under the original F scale, an F5 rating was given as follows ... Oklahoma, on May 20, 2013. The last official EF5 tornado to hit the U.S. was the infamous 2013 Moore, Oklahoma, tornado.

May 20, 2013, marks the last ... now than it was to attain an F5 rating on the legacy Fujita scale," Lyza said. "As we illustrate in the paper, every single tornado of the EF-scale rating era ...