Tornado study to dive into storm's heart This funnel cloud formed April 10 in Keo, Ark, although no tornadoes on the ground were reported. A band of hail, heavy rain and twisters pounded Arkansas, Texas and Oklahoma Thursday, damaging hundreds of homes, flooding roads and leaving thousands without power. U.S. scientists plan the most extensive tornado study since one in the mid-1990s that helped inspire the Hollywood film Twister. Starting in spring 2009, researchers intend to hunt tornado-spawning thunderstorms in the central part of the country.