A ripple of energy in the atmosphere over the Carolinas is pushing northeast around the mid level trough in the atmosphere. This energy is producing rain and thunder in the Carolinas this morning and will push into our region tonight and early Monday, producing areas of rain and thunder for us.
We could see the first fingers of moisture into Delaware this afternoon, into South Jersey by evening, with steadier showers pushing north towards the late evening hours. Below are a couple of graphics from the NAM that show those showers pushing northeast, with the first wave of showers moving through South Jersey by 10 AM and a steadier, second wave down in Maryland and Virginia for later tonight.
Rain could be heavy at times later tonight for Delaware, South Jersey, and even into the Philly metro itself if the NAM is right. The Euro brings the axis of heavier rain mainly across New Jersey and northern Delaware while the GFS is very weak with the system and pretty much just brings nuisance showers. It's hard to think the GFS solution is right given that the rain at current is outproducing what the GFS suggests will fall by this point.
At minimum, expect a round of showers later this afternoon and this evening spreading up from the south, a steadier period of rain that continues later tonight and into early Monday morning, followed by rain tapering off from southwest to northeast through the latter half of the morning rush hour on Monday.
Rainfall totals could approach or exceed an inch in a few spots tonight across parts of the region.