tornado. it was a very slow-moving storm. so we had plenty of time to get out of its path. >> just because the way it's getting bigger, it's right here. >> reporter: then on monday, may 20th, they planned their next moves. >> we looked at the weather models. predicting where the strongest winds aloft are going to be, where moist air, where the surface boundaries are located that will initiate storms. >> we actually started out going south of the norman and moore area. we were looking at the radar and it had what we like to say, just the look, of a strong thunderstorm. and that's when we made the decision to go north on i-35. >> if you're anywhere from just north of new castle right into moore, this is your storm. >> reporter: just before 3:00 p.m. central time, cnn meteorologist chad myers spotted the telltale sign of a developing tornado. >> you look down and it was a ball. the next scan, the next time i