Parts of Long Island can expect a white Christmas Eve, as about half an inch of snow is expected to fall Tuesday morning, the National Weather Service said. Bryan Ramsey, an NWS meteorologist, said a line of snow showers will approach New York City and move east beginning around 7 a.m.

A White Christmas in upstate New York is looking more and more likely. With several inches of snow already on the ground, it isn't a certainty, but is certainly likely, said Meteorologist Bob Hamilton of the National Weather Service in Buffalo.

First, let's define our terms: according to the National Weather Service, a white Christmas happens when there is one inch or more of snow on the ground on the morning of the holiday.