I feel like the models are slowly pushing this entire thing NE. The Mid-Atlantic gang already busted. Next up is PHL and NYC. They probably aren't getting 2 feet.
It seems like this storm is evolving and the models are playing catch-up. 18z Euro moves the snowfall max to NH and Maine, out of SNE...
I get upslope enhancement from the NW, N, NE, and E directions. So that's not an issue here. I think the 18z just blows up the GOM low a little later and less strongly than 12z. Still 20" here so no complaints.
Based on the GYX distro, they seem to be hedging a lot about what happens after the first thump and the low occludes before firing again. They say totals may need to climb significantly if that second piece comes to fruition. It sounds to me like they are riding the GFS.