Snow will start light tonight. Late Monday night through early Tuesday morning will be when the heaviest of snow will fall. Snowfall rates of 2-4 inches per hour are likely in NYC and Boston. Once all is said and done I would not be surprised if we get a snowfall report of 3 feet or higher. We saw it in 2013 when Hamden, Connecticut got 40 inches of snow because of a very heavy snow band.
Wind will be a major problem with this storm. The area with the strongest winds will be Cape cod where wind gusts will likely surpass 70 mph. It isn't shown on the map but Nantucket could have wind gusts even higher. Perhaps reaching 80 mph. These strong winds will also create whiteout conditions in New York City and Boston. Snow drifts from strong winds will likely be double of how much snow actually falls. For example if you get two feet of snow, snow drifts could be as high as four feet.
3. Coastal flooding
Coastal flood watches that will likely become warnings have been issued in Massachusetts. On the New Jersey, Long Island and Connecticut coast expect some minor coastal flooding. On Rhode Island expect minor flooding with a few pockets of moderate flooding. On the Massachusetts coast expect moderate coastal flooding with a few pockets of major coastal flooding.