As of now, the setup does not comparable to the one that produced the derecho last June across South Jersey and Delaware but the risk of severe weather is pretty high for this part of the world. We're under a slight risk for severe weather in the city and points south (30% chance for Central and Southern DE as of now); however, I do believe that areas north of the city to around Allentown and Reading should be weary that if the disturbances track a bit further north, you guys will also run the risk of severe weather. Heavy rain is a risk for everyone. With any thunder complexes that move through later this week, the potential does exist for more heavy rain to fall.
As the front will be tortuously close to Philadelphia, we do have to keep an eye on this as the potential for heavy rain will yield more problems around the region. After five to seven inches of rain in much of the immediate Philadelphia region since Friday, any bit of extra rainfall is liable to quickly run off and cause problems as the ground is saturated.