"you'd better be a weather nut or you are going to be bored out of your mind," warns veteran guide Marty Feely, who has run WhirlwindTours of Norman, for four years. Twister "is the Indiana Jones treatment of storm chasing."

"In the movie, they saw six tornadoes in one day and had a nice leisurely lunch," notes Christi Endebrock, a substitute teacher from Effingham, Ill., who's twice taken Feely's tour and viewed the tornado featured on Twister's poster through binoculars on May 28, 1994. We're usually stopping in convenience stores, grabbing junk food and slamming it down."

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Hazards include lightning and hail, but the biggest danger, according to Gary England, chief meteorologist for Oklahoma City's KWTV, comes from humans. "People drive and say, 'Ooooh, look at that.' Next thing you know, you're in a wheat field."

When there's no weather to hunt, most guides teach forecasting basics and offer general sight-seeing; this year Feely stopped in Wakita, Okla., where Twister was filmed. But when the chase is on, be ready. "We recommend you don't drink too much," says Charles Edwards, who operates Cloud 9 Tours, also out of Norman. "We may not have time to take too many pit stops."