Snow is already moving into the area but mostly in the form of virga (not reaching the ground). The main event should come in around 4-6PM and last until 10-11PM. If you are in NJ and LI things will need to be watched for the coastal development as many SREF ensemble members show forcing increasing fairly rapidly as the coastal develops. This is not going to be a big surprise but with temps so low anything will stick so if some of the SREF members are right we could see 2" in some spots in NJ with more towards LI.
The winner for this event will go to Southern New England where it wil snow longer, but dynamics are going to be pretty impressive. Check out the sounding from Boston:
That is nearly 50J/Kg CAPE in the lowest 3km! And it goes right through the dendritic snow growth layer in very cold temperatures favorable for very high ratios. This is going to come close to a "norlun" criteria I think, but these are so hard to pin down. So if you are in MA and ME watch out for this as snowfall rates could reach 4"/hr at times!!!