are leaving a storm zone, they are the men and women going in. the up side is, you ve seen their work and they ll leave us with the videotaped record of this storm and others. one such storm chaser story tonight from nbc s lester holt. reporter: eastern mississippi, wednesday afternoon. dark clouds gather. to the trained eye behind the camera, it s clear this could be very bad. it could produce right now. watch as the winds begin to swirl, and then something rarely caught on camera. out of thin air, a tornado is born. instead of seeking shelter, the cameraman guns it, racing torwards a storm that would eventually devastate parts of alabama later in the day. large tornado. 24-year-old andy gabrielson is a storm chaser.