In May of 2011, Joplin Missouri was hit by the deadliest single tornado since record keeping began in 1950. After that disaster, the National Weather Service evaluated their warning system and public response to it. That led to a more specific warning system that went into effect in Iowa on April 1. Today we hear from two Iowa National Weather Service meteorologists about the new “impact-based” warning system. We also listen back to our conversation last year with storm chaser Jeff Piotrowski and his firsthand account of the Joplin tornado.