Study: Biggest tornado outbreaks are spawning more twisters

WASHINGTON (AP) — The most extreme tornado outbreaks are mysteriously spawning many more twisters than they did decades ago, a new study claimed. The once-every-five-years-or-so outbreak that might have involved 12 tornadoes 50 years ago now has on average about 20, said Columbia University applied physics professor Michael Tippett, lead author of the study in […]