NEW GFS

The low begins to develop off New Jersey coast but its still far enough offshore to keep the heavier qpf offshore.  On this frame two different distinct s/w's are phasing or coming together to produce this low pressure system.  The main culprit is the Polar Vortex over the Hudson Bay.  That prevents this from turning the corner sooner. 

The OLD GFS:

Notice how the low develops later is has the qpf further offshore and to the north.  The main reason why this happens is because the s/w's merge too late for us to get hit.  Even more so the second s/w does not dig as much as a result it is forced to meet up too late for us.

NEW GFS

I highlighted the two distinct pieces of energy that come together.  You can see this happening in the frame above.  But as I mentioned before the main player is that polar vortex.  In the 12hrs from the older run to the newer run this shifted the PV to the SW.  The significance of that is it brings in the s/w in a much favorably trajectory and allows it to dig and phase sooner.  Hence the low developing off NJ coast now.

The OLD GFS

PV is an unfavorable spot and shows the s/w at a higher latitude and not as favorable.

Summary:

If the GFS continues this shift slightly in the coming model runs we could see a nice low blow up right off the coast and give a good snow event for portions of the Northern Middle Atlantic.  Something to watch out for, but regardless a light snow event is likely from this system whether it be a plain clipper or a clipper with a coastal enhancement!