You have to be careful when looking at 6-hour maps:

I know there are others talking about snow on Long Island and severe flash freezes, but you can get much more accurate data when you look at the hourly GFS maps (1st image), as opposed to maps that average the precipitation rate and type over a 6 hour period (2nd image). I am not saying there can't be a snow shower (the possibility is even in my forecast), but don't expect much, if any, back-end snow on Long Island; look at the hourly radar at 5 PM Friday in the 1st image. As for a flash freeze, yes, some black ice is likely, but just how widespread it is remains to be seen as the National Weather Service covering Long Island is saying the following: "Behind the cold front, temperatures may drop 10 to 15 degrees within 1 to 2 hours behind the front. Since highs are forecast to get well into the 50s Friday, a flash freeze seems unlikely at this time." The truth is likely somewhere in between, and I have posted all about the rapidly dropping temperatures many times already