The National Weather Service has issued a flash flood watch for the region through Friday morning.

Heavy rainfall will develop over portions of eastern Pennsylvania and northwestern New Jersey ahead of Tropical Storm Elsa through this afternoon. The area will see 1 to 2 inches of rain with locally higher amounts at that time. Another 1 to 2 inches of rain is expected with Tropical Storm Elsa tonight into early Friday morning.

Heavy rain in a short period of time may cause streams and creeks to rise quickly out of their banks and there is the potential for flash flooding in areas of poor drainage.

The latest forecast:

Today: A chance of showers and thunderstorms, then showers and possibly a thunderstorm after 1 p.m. Some of the storms could produce heavy rainfall. High near 82. Calm wind becoming south around 5 mph in the afternoon. Chance of precipitation is 80%. New rainfall amounts between a quarter and half of an inch possible.

Tonight: Showers and possibly a thunderstorm. Some of the storms could produce heavy rainfall. Low around 66. Southwest wind 5 to 10 mph becoming east after midnight. Chance of precipitation is 90%. New rainfall amounts between a quarter and half of an inch possible.

Friday: Showers likely, with thunderstorms also possible after 2 p.m. Partly sunny, with a high near 82. Northwest wind 5 to 10 mph becoming west in the afternoon. Chance of precipitation is 70%. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Friday Night: A chance of showers and thunderstorms before 8 p.m., then a slight chance of showers between 8 p.m. and 2 a.m. Partly cloudy, with a low around 63. North wind around 5 mph. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Saturday: Mostly sunny, with a high near 79. North wind around 5 mph.

Saturday Night: A chance of showers before 9 p.m., then a slight chance of showers after 2 a.m. Partly cloudy, with a low around 60. Chance of precipitation is 30%. New precipitation amounts of less than a tenth of an inch possible.

Sunday: A chance of showers between 8 a.m. and 2 p.m., then a chance of showers and thunderstorms after 2 p.m. Partly sunny, with a high near 79. Chance of precipitation is 50%.

Sunday Night: Showers likely and possibly a thunderstorm. Mostly cloudy, with a low around 64. Chance of precipitation is 60%.

Monday: A chance of showers, then showers likely and possibly a thunderstorm after 2 p.m. Partly sunny, with a high near 82. Chance of precipitation is 60%.

Monday Night: Showers likely and possibly a thunderstorm before 8 p.m., then a chance of showers. Patchy fog after 4 a.m. Otherwise, mostly cloudy, with a low around 66. Chance of precipitation is 60%.

Tuesday: Showers likely and possibly a thunderstorm. Patchy fog. Otherwise, partly sunny, with a high near 84. Chance of precipitation is 60%.

Tuesday Night: Showers likely and possibly a thunderstorm. Partly cloudy, with a low around 66. Chance of precipitation is 60%.

Wednesday: A chance of showers and thunderstorms. Mostly sunny, with a high near 84. Chance of precipitation is 40%.