Severe weather is definitely possible this afternoon and evening across the Delaware Valley as a cold front approaches from the west. Showers are in Western Pennsylvania this morning out in front of the front itself and will help set the stage for thunderstorm development later on today. Anything that develops will likely fire in Central PA in the midday and early afternoon hours, moving east and east-northeast towards us.
In terms of risk, wind is the larger risk for severe around here, with a 30 percent chance that any one location within 25 miles of you picking up severe criteria winds (higher than 58 mph) at some point today. Hail is also possible but wind is a larger threat with these storms.
The risk for severe weather is greater west of I-95 than east, due largely to timing as the storms should approach the western suburbs after 3 or 4 PM this afternoon. An earlier arrival of those storms may increase the risk of stronger storms across New Jersey this evening as some daytime heating will be available for storms to feed off of as those storms approach the coast. As of now, it looks like the city's "prime time" for thunderstorms to impact it is between 5 and 8 PM.
The high resolution NAM does show the potential for a line of thunderstorms this evening, with other showers and storms farther to the west. In addition to the threat of damaging wind and hail, heavy rainfall is also likely in any thunderstorm activity and some locations could pick up an inch, perhaps more, of rain.
Other modeling does show the potential for scattered areas of thunderstorms after 4 or 5 PM...so the potential definitely does exist.
You should be able to get through the morning and midday hours ok around here but the later into the afternoon we get, the higher the odds will be for thunderstorms to impact your outdoor activities.