Comments on the storm from the NWS and TWC:
The National Weather Service covering Long Island and the tri-state area and The Weather Company are still both leaning towards mostly snow, but they leave open the possibility of more rain for the coast. It's going to be a very close call for Long Island.
Both images are from The Weather Company, and here are comments from them and the NWS:
The Weather Company:
1. Accumulating snow is likely along the I-95 corridor from Boston to New York, Philadelphia, Baltimore and Washington D.C., some of which may be significant amounts of snow. More than a foot of snow is likely and some disruptions are likely. But some rain may also occur for a time, especially closer to the coast.
2. Winds could be strong, particularly along the coast.
3. Wednesday and Wednesday night appear to be the peak of this East Coast storm, though some snow could linger into early Thursday.
National Weather Service covering Long Island and the tri-state area:
A southern stream low pressure system moving across the lower Mississippi Valley Tue night will weaken W of the Appalachians on Wed while a secondary low takes shape near Hatteras. This system will have plenty of Gulf and eventually Atlantic moisture to work with, as well as a continued supply of low level cold air from the strong high to the northeast, so as this system approaches, expect snow to develop Wed afternoon, and then become moderate to heavy at times Wed night as the low wraps up just off the Mid Atlantic coast. Forecast mentions almost all snow at this point with a good chance of significant accumulation, with the caveat that the high to the NE may be modeled too strong, and if the high does retreat more quickly that could allow for a more N/W low track as well as potential for mixed precip for the NYC metro area and Long Island as marine air and possible warmer air aloft get involved.