Tornadoes Are Coming in Bunches. Scientists Are Trying to Figure Out Why.

Tornadoes tend to travel in packs these days, often with a dozen or more forming in the same region on the same day. On the worst days, hundreds can form at once.More than a dozen tornadoes were reported on both Monday and Tuesday this week across the Great Plains and the Midwest, according to the Storm Prediction Center run by the National Oceanic and Atmospheric Administration. Two weeks ago, on the most active…