With our next slow moving front bringing rain to a chunk of the region today, and most of us later tonight through tomorrow, the question turns to "how much" will ultimately fall. Computer modeling varies a bit on rainfall through Wednesday at 8 AM, but the trend is that more rain will fall north and west than it does south and east. Using the NAM as a guide, you can see the visual difference in rainfall over South Jersey compared to what may fall in Southeast PA on west and north.
The heavier rainfall later today and tonight will reside west of the city, with the rainfall axis shifting into North Jersey later tonight, with another shot of steadier and heavier rainfall possible on Tuesday for parts of the region. Modeling varies on Tuesday's round from it scooting mainly through the city and western burbs in the morning (NAM/Euro) to mainly New Jersey (GFS).
Computer model output varies a bit on rainfall totals as well, with the GFS the most aggressive on rainfall for all as it spreads round two out a bit more geographically and the NAM/Euro close to each other on rainfall thinking, but the consensus is that rainfall amounts should avoid reaching the three inch barrier by Wednesday morning except in isolated locations.
Minor flooding is certainly possible with this event, especially in areas that approach that three inch range. However, the odds of a widespread flash flood along a stream appear low at this point. Could get some of the usual suspect streams to get close to the top of the bank, though, with this event.
We'll keep an eye on rainfall over the duration of this front's slow track through...and you can look as well by checking out our current weather page.