The Weatherman

So I’m driving to work this morning, and the rain is coming down pretty hard. Listening to the BBC for world news on the local radio station, when they give the day’s weather report. So, as a reminder, the rain is coming down pretty hard, when they guy on KEOS gives the weather forecast… High of whatever, low of whatever, it’s cloudy, and there is a 70% chance of rain. So, it’s raining. Why do they tell you it’s a 70% chance when the rain is coming down?