Rain is pretty much inevitable later today as an almost textbook example of a mid-latitude storm system continues to slowly creep eastward. The original low is still near Chicago and a secondary low is forming along the Mid-Atlantic coastline. Both systems are pulling gobs of warm, moist air northward from the Gulf of Mexico and the Atlantic. The latter source may soon be joined by tropical humidity streaming ahead of Hurricane Gonzalo. Moderate-to-heavy rain has reached eastern Pennsylvania and should be arriving here early this evening. This afternoon's high of 75 degrees is about ten degrees warmer than normal.
It's all about the rain tonight and tomorrow. Rain, heavy rain, maybe even a thunderstorm are likely overnight. A couple inches of rain are possible by morning. But, wait, there's more! Rain and thunderstorms are possible again tomorrow, when we could see up to another inch of water. It looks like the rain will end early Thursday evening. Tomorrow's high should reach the low 70s.
Friday is looking good! A cold front will pass through the city Thursday night but there is not much cold air behind it. Friday and Saturday should be mostly sunny with highs near 70 both days. Saturday should be mostly sunny and only slightly cooler. We'll be lucky to see 60 degrees on Sunday following the passage of another cold front.