100% chance of rain

Much like our local weatherman, I usually take the guestimation approach to the weather. I get up, make an assessment, and then am either dressed appropriately or not, accordingly. I don't lose a lot of sleep over the vagaries of weather prediction technique and technology. Lately, though, our weatherfolk appear to have been hedging their bets by adding percentages into their forecasts. While I'm a big supporter of the "hedge your bets" approach to forecasting. the recent rash of forecasters predicting "100% chance of rain," strikes me as more of an oxymoron then a hedge. All of this lead me (and my friend) to wonder whether "100% chance of rain" actually means something other than "it's going to rain. bring a coat."

It turns out that "100% chance of rain" actually means something. Go figure. A little piece of weather trivia for the day.