Before I leave I check www.weather.com and look ahead 5 days for severe weather. That way I can change routes if necessary to avoid bad weather. If possible we wait until the weather passes. If not we stay put until it passes and ask where the shelter is at the campground. We have the weather radio from Walmart. Has S.A.M.E. option. About $30. We keep it plugged in and can hear it in our class A. If you are in a truck, you should get a hand held portable weather radio. I'm not sure that a cell phone would work in some areas if you lose signal. Weather channel has an app. Maybe do both. Get the app and a hand held weather radio. Always have a plan.
