A flash flood warning is issued when a flash flood is either imminent or already occurring. In flood-prone areas, it’s crucial to move immediately to higher ground. A flash flood is a sudden and violent inundation that can develop within minutes to hours, and it can even happen in areas not currently experiencing rainfall.

Heavy rain moved out Wednesday morning in the Philadelphia area and several streams and creeks are dealing with more water than normal.

Torrential rain led to a flash flood emergency in Western Maryland, with up to two inches of rain per hour forcing rivers and streams over their banks and into the streets.