A massive tornado developed right in front of their vehicle. Actually, they were probably a little closer than they'd hoped. The twister intensified right on top of the car they were riding in registering wind gusts of 138 mph on the car anemometer. 

Why do these guys do it? They say it's for the adrenaline rush, the experiences of a lifetime, and the chance to sell the video to the Discovery Channel for national TV broadcast. Look for more video from these guys on the Storm Chasers new season which airs this fall on Discovery Channel.