What are "Rain Chances"

Why do you have to have a PhD. to be considered a meteorologist? Do you need a doctorate to be considered an engineer? An accountant? A nurse?

Four hours before Hurricane Andrew, yes way back then, the weatherman said there was a 100% chance of rain and followed that with saying it was the first time he’d seen the figure of 100% chance of rain.

Nate Silver’s book goes into this in a lot more detail. Weather predictions are statistical. He also notes that local stations have a bias in predicting rain, less so for the Weather Channel and even less so for NOAA. The bias comes from the viewers being happier if they predict rain and it stays dry versus not predicting rain and the viewers getting wet. He gives data on this, of course.