One inch of snow was measured in Central Park at 7 a.m., and the National Weather Service announced an official white Christmas.

It's official, it's a white Christmas in New York city with at least 1 inch of snow on the ground in Central Park Wednesday morning. It's the first white Christmas for the Big Apple since 2009.

In the tri-state, some will get a White Christmas and some will fall just short. Christmas Eve’s morning snow totaled near an inch in many places near the coast with higher totals – between 2 and 3 inches – for northwest New Jersey into the Catskills and Hudson Valley.

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.

Those areas along the Great Lakes, as well as those in central and northern New York, all have a “high” probability of enjoying a white Christmas. Meanwhile, parts of the Finger Lakes region and the Catskills region have a “medium” chance of waking up to snow on Christmas day. Although the odds are low for New York City, they are not zero.

Snowy weather during the Tuesday morning rush hour should leave behind about half an inch of accumulation, according to Bryan Ramsey from the National Weather Service. With some places – like Central Park – still covered in some snow from winter weather over the weekend, the total could be enough to last until Christmas Day.

Around 20 million people were under winter weather alerts across parts of the mid-Atlantic and New England, including Philadelphia and Burlington, Vermont.