A Northfield, Minnesota, tornado clocked in at 459 megajoules. 
Mitch Dobrowner
On May 20, 2013, a mass of swirling wind gouged a path of destruction across Oklahoma, killing 24 people and causing $2 billion in damage. And earlier this week a deadly cluster of tornadoes ripped through the midwest and the south, killing more than dozen people and injuring hundreds. This kind of destruction would seem to indicate that tornadoes are getting worse. But with the way we currently measure twisters, it’s nearly impossible to know. Now James Elsner, a geographer from Florida State University, has a fix.
See, meteorologists use the Enhanced Fujita Scale, which looks at damage to buildings and vegetation to rank a storm from EF0 to EF5. But that’s subjective, and it doesn’t work well in areas with few structures or trees. And you can’t look inside the categories to see if one EF5 storm is stronger than another.
A tornado-power equation that actually gauges a twister’s kinetic energy would be more useful to scientists who are also examining the effects of climate change, so that’s what Elsner built. He looked at the length and width of a storm’s damage path, correlated that to the amount of damage, and then used the result to estimate wind 1.0 speed. A little more crunching and bam!—integrated kinetic energy of a storm. Non-linear upward trend estimated values of kinetic energy Elsner’s analysis suggests that since the turn of the century, tornadoes have packed a more powerful punch. Which, if you live in Tornado Alley, totally blows.
