The 00z model guidance has rendered me speechless, and my fingers just barely work enough to allow me to type this post.

The first runs of the 00z suite, the NGM and NAM, are a change from their previous runs right from the start. By hour 24, the trough is already showing signs of a more negative tilt, and more consolidated energy. By hour 48, it is much sharper, and by hour 60 (Tuesday morning) the trough is tilted notably negative with a vorticity maximum riding around the base to the east side. At the surface, things are little delayed still, but the low does cut north much further west, with rapid intensification occuring just east of Cape Cod. Verbatim, this would be a double digit snowstorm to much of the Mid Atlantic and New England regions, with blizzard potential on the backside.

Still waiting on the rest of the guidance: GFS will be within the next hour, and Euro a few hours after that. I have a feeling though, these models will follow what we've seen so far.

Why the change? One valid possibility is that the energy that will be driving this storm was located over the North Pacific (specifically devoid of data at the moment considering flight traffic being rerouted around Redoubt in Alaska). Now, it is moving ashore across western Canada, where there is much better data collection.

How far west will this end up going? Very hard to say. There has been so much model instability as of late, that notable changes in the future are definitely possible. I feel more comfortable again saying that there will likely be a major storm in the eastern US next week, regardless of the details.