Thunderstorms, Heavy Rainfall In PA Forecast Wednesday: See Where

PENNSYLVANIA - As temperatures finally begin to fall in Pennsylvania this week, chances of thunderstorms are set to increase, forecasters said.

Multiple rounds of thunderstorms and showers may hit the southeastern region this week, starting Wednesday with a chance of storms around 3 until 11 p.m. interspersed with sunshine, according to the National Weather Service. Showers are likely to follow suit in the wee hours of Thursday morning with some storms capable of producing heavy rainfall.

As of 5 a.m. on Wednesday, several counties are under an excessive rainfall outlook, including, Somerset, Bedford, Fulton, Franklin, Berks, Lehigh, Northampton, Adams, York, Lancaster, Montgomery, Delaware, Philadelphia, Chester and Bucks counties, the National Weather Service said, with isolated flash flooding possible.

“Precipitable water values will likely remain in the 2 to 2 1/4 inch range in those areas, so locally heavy rainfall is possible,” the National Weather Service said in a forecast discussion Wednesday morning. “The potential for thunder and heavy rain will be lower across Berks County, upper Bucks County, Central New Jersey and points northward due [to] the lack of deep moisture and their distance from the front and weak surface wave.”

The gloomy forecast will continue Thursday with temperatures near 85 degrees, per AccuWeather, and a chance of showers and thunderstorms set to hit the region before 2 p.m., though it’s not clear where major impacts will be yet. Thursday afternoon will gradually clear up with partly cloudy skies; the evening forecast will be entirely dry, forecasters said.

“The coverage and timing of the showers/thunder however will depend on the details of an impulse exiting and then how fast some drier air arrives in its wake,” the National Weather Service said. “There could be a few showers/thunder getting to our far northwest zones later Thursday afternoon with the main cold front, however a south and eastward extent is less certain given the later timing and lowering instability overall.”

The silver lining: Friday’s forecast remains mostly sunny with a high near 82 degrees, per AccuWeather.

Here's the latest forecast, per the National Weather Service:

Wednesday: A slight chance of showers and thunderstorms after 3 p.m. Mostly sunny, with a high near 88. North wind around 5 mph becoming west in the afternoon.

Wednesday Night: A chance of showers and thunderstorms before 11 p.m., then showers likely and possibly a thunderstorm between 11 p.m. and 1 a.m., then a chance of showers and thunderstorms after 1 a.m. Some of the storms could produce heavy rainfall. Mostly cloudy, with a low around 71. Southeast wind around 5 mph becoming calm. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Thursday: A chance of showers and thunderstorms before 2 p.m. Partly sunny, with a high near 85. Calm wind becoming north around 5 mph in the afternoon. New rainfall amounts of less than a tenth of an inch, except higher amounts possible in thunderstorms.

Thursday Night: Partly cloudy, with a low around 66. Calm wind.

Friday: Mostly sunny, with a high near 82. North wind 5 to 10 mph.

Friday Night: Mostly clear, with a low around 60.