Henry's Bravada is the fourth SUV he's built for chasing. Inside, it has a full rollcage as well as fabricated steel brackets to hold an assortment of weather, police, and ham radios, along with two laptop computers. One laptop runs a GPS map; the other has links to satellite weather images. The rear luggage compartment has tools and emergency rescue equipment. Two modifications underhood are an automatic transmission shift kit and a low-restriction exhaust.

Faidley has similar equipment in his chase SUV, but also has foot-long sections of PVC pipe fastened to the rear floor: These hold ready-to-use telephoto-equipped cameras. All the vehicles have extra amber emergency warning lights, and in Texas it's legal to use "wig-wag" circuits that alternately flash left and right headlights. "When people see us coming, they're usually ready to pull over, get out of their cars, and find shelter," says Faidley, who's been selling tornado photos and video for 13 years-you may have seen his images on the Weather Channel. "A lot of times, cops follow us because they know we're not going to get caught in a wedge." (Chasers call twisters "wedges.")

A big problem is overheating when storm debris clogs radiators. Faidley's and Henry's grilles have screens to catch sticks, leaves, bugs, and mud. Hail also can puncture a radiator, as well as smash the windshield. Faidley replaces the windshield of his Explorer once each season due to baseball-size hail damage. Everything inside the car must be fastened down, too: Faidley's seen wind gusts suck maps and clothing out of open windows.

Each day, the chasers choose a state where a storm system is forecast, then spend the day driving there, often averaging 500 miles. Storms usually don't fully develop until day's end, when the sun has warmed the ground enough to produce rapidly rising heated air. But Faidley and Henry and crew don't chase after dark or in regions with tall trees. "You'll never see a tornado coming if you're under trees," Faidley says. Each time the chasers pass a small town, they keep track of awnings and overhead shelters where they might later have to hide their SUVs from hail.