As the 10pm newscast drew near one night last month, the chief meteorologist of Birmingham's ABC-affiliate began to get worked up. Balding and characteristically attired in suspenders, James Spann is one of the most recognizable and respected local TV meteorologists in the country. But he had a familiar problem. The day had been pleasant in Alabama, and more of the same temperate spring weather lay ahead—so what the heck was he going to talk about? “I’ve got 2 minutes and 30 seconds to fill,” Spann explained. “Everyone in my audience is going to know what the weather is going to do. Except maybe my mom. She’s 85 years old. But most everybody has looked on their phone or some other device already. So what am I going to do? Am I just going to rehash everything they already know?” Many forecasters have been asking themselves this question lately. Two technologies have converged to rapidly displace the primary function of meteorologists. First are computers that are generally be...