Models remain pretty much on course for a 1 to 2 inch rainfall. Both the GFS and NAM have a similar idea. One thing that is happening is that the front is moving slower and slower so that pushes the threat for downpours back by a few hours. It will begin sometime after midnight in Western areas of New Jersey and continue to spread east during the early morning hours. The bulk of the rain will probably be Friday morning.



The main difference between the two models is that the NAM cuts off the heavier precip south of Central New Jersey while the gfs extends that area all the way southward into Delmarva. There should be enough tropical inflow to cause a widespread rain. We can certainly feel it out there too with the high humidity. The sky has almost a Florida look to it with multilevel clouds and not much haze.
gfsprecipTrying to pinpoint rain amounts in a situation like this is always difficult. When you look at the nam surface profile with the radar simulation on it, the line of storms is pretty narrow. One is going to have to bank on the slow moving nature of this and the tropical air to generate some decent amounts and it is certainly doable from that respect. The air masses ahead and behind this “front” are pretty similar so we are going to really have not much change in the overall flavor of the weather right through the weekend. Once the rain is done it is back to very warm and very humid with pop up thunderstorms.nam42

nam48With regards to any real change in air mass we will have to wait until perhaps Tuesday when a stronger front arrives with some genuine cooler air behind it. In the lower corner by the way that is the GFS showing Tropical Storm Dannygfs168With the trough like that Danny (if it is really there) would recurve up around and out…but that depends a lot on whether the trough extends far enough south to pick it up, or is it going to lift out and leave it meandering there and wait for the next possible trough. Or a ridge might build and force a track westward. I think you get the idea here that there variables at this point make postulation anything regarding Danny beyond the short range is beyond ridiculous and a time wasting adventure.