National Weather Service says Philly region hit with up to 10″ of rain ‘100- year flood’ Monday – and it most likely won’t be a century before the next one

100-year flood: Thunderstorm training late Monday afternoon turned an average storm into a flash flood emergency in Bucks and Burlington counties, creating what the National Weather Service later called a “100-year flood.” But the phrase doesn’t mean what you think it means.
Source: pennnews