Heard in a news-talk station's air check from the '70s: "Chances of measurable precipitation are just five percent today..."
I think that's the only time I've ever heard an announcer mention a five percent chance of rain. The thoroughness and consideration for the listener there impresses me. It's a good way of saying, "It probably won't rain, but there's still a slim chance of it."
I can't remember the last time, however, that I heard any radio announcer mention a chance of rain below 20 percent.
