Area is under flash flood watch

With rain in the forecast through Friday night, a flash is in effect for the Philadelphia area until at least late tonight.

A flash flood watch is a step below a flash flood warning and means condition may develop for waterways and roadways to suddenly become flooded.

The National Weather Service, which issued the watch, said showers and thunderstorms are expected to produce heavy rain into Friday night and may prompt additional flooding concerns.

The region's rivers and streams - including the Delaware River and the Schuylkill - remain well below flood levels.

However, parts of the region have been hammered by the capricious rains of the last week. Through Wednesday, 2.3 inches of rain had fallen in the previous seven days upon Gloucester and Camden Counties, or 2 1/2 times the normal amounts. Rainfall in Delaware County was double normal.

The heaviest rains this afternoon are expected west of the city.

Any rain that falls, or has fallen, won't be evaporating much, given the saturated air and a brooding, persistent cloud cover.

Because of those clouds, Philadelphia International Airport has advised travelers of delays of more than an hour.

And in South Jersey, Camden County announced a South Philadelphia String Band concert set for 8 p.m. at Cooper River Park had been canceled because of the rainy forecast.

On a positive note, the forecast for Saturday and Sunday calls for clear and sunny skies.