Parts of the Philadelphia area are under a Flash Flood Warning until 6:30 p.m. Thursday night. Brad Paisley gave fans a night to remember when his latest concert turned into a full-on comedy sketch involving local police officers.

Most of the rain is forecast to fall in as little as 3-6 hours. A small chance of heavier rain and flooding could pose "an elevated threat to life and cause significant disruptions to transportation, flood underground infrastructure and basements and first floors of residences and businesses," with water rescues needed, the weather service said.

New York and New Jersey have declared states of emergency as rainfall reaches up to 2-3 inches per hour in some areas.