On a trip from Topeka to Texas a month ago, I used a weather radar app on my iPhone. I opened the app, hit the arrow for "my location", and then hit the button for animation. I could see when one of those big ol T-storms was going to cross my path, and we would pull over until it passed. This was the week that they had all of those nasty tornados.
Also - be very very very very careful crossing western New Mexico and Arizona on I-40. The winds get so bad there (on a clear day) that they have to close the interstate. My friend had a 30 ft toy hauler flip over and take her TV - which rolled three times - while going 35 mph down I-40 westbound. Both vehicles totaled but luckily no one hurt.