Don't let the sunshine Thursday morning fool you, you will ilkey need an umbrella because parts of Pennsylvania, New Jersey and Delaware could get a soaking of 2 or more inches of rain in an hour.
"You'll need sunglasses this morning and umbrella this afternoon," said NBC10 First Alert weather meteorologist Bill Henley
The National Weather Service Issued a Flash Flood Watch into Friday evening for all of South Jersey, all of Delaware and Philadelphia and the immediate suburbs in Pennsylvania.
Forecasters are still unsure of the track, but they say periods of showers and thunderstorms are expected from Thursday night into Friday.
Rain could already start falling around noon in points south of Philly.
"The greatest threat is to the south: for Delaware, South Jersey... this is where we are most likely to see severe storms take shape this afternoon," said Bill. "The farther north you go, the less likely they are. But there are still going to be showers and thunderstorms around even if they are not severe.
Thursday afternoon and evening -- during the evening commute -- could be when the heaviest rain hits, said Bill.
The storms have the potential to knock down trees and knock out power, said Bill.
Temps pushing into the 90s should fuel the storms.
"One of the keys to the storms really strengthening this after is the warm-up that happens before they move in," said Bill.
People are urged to not drive or walk through floodwater.
"Flash flooding is a very dangerous situation," said Philadelphia Mayor Jim Kenney. "Whether you’re driving, walking or riding, we urge you to stay clear of potentially flooded roadways and seek shelter during heavy rains."
Keep checking back with NBC10 for the latest First Alert Neighborhood Weather forecast.