If you're interested, read the NWS NY (covering Long Island) forecaster discussion below:

It shows you what goes into making a forecast and the complexities involved. Even if you don't understand it all, you'll get the gist. Also, notice how they mention the temperatures dropping Saturday from late morning through the afternoon. This will be a very powdery high-ratio snowfall! I wonder if a Blizzard Warning will be issued for all of Suffolk or only the eastern half of Suffolk.