A sunny afternoon can turn ugly real fast in Tornado Alley - and it's about to. The four chasers were strangers, with only a common interest in bad weather and tornadoes. They found each other on the Internet last year. Seven months and hundreds of E-mail messages later, they found themselves roaming the plains in a rented Winnebago in search of the elusive twisters. On May 24, the atmosphere over north-central Oklahoma and south-central Kansas is a weather bomb ready to go off. At 3:28 p.m. in Ponca City - a town that owes its prosperity to oil, not grain - it is a sticky 85 degrees. A hot 12 mph wind blows off the ocean of green wheat from the west. At 69, the dew point is excellent - lots of moisture hangs in the air, but not too much to drown a tornado's delicate birth process. This day brought the chase team what they were looking for: jackpot - a storm which contained over twenty tornadoes.