50 million Americans on alert for heavy snow
Some 50 million Americans are on alert for heavy snow in the northeastern United States on Tuesday, as a storm is forecast to hit the region in the morning hours before exiting by the afternoon.
It's the first time in two years that the National Weather Service has issued a winter storm warning for New York City.
Rain began changing to snow early Tuesday and much of New York City was already under snow by 5 a.m. ET. The freezing line hadn't quite made it to Philadelphia at that time but was expected to soon.
Since this is a wet snow falling into temperatures that are generally at or above freezing, the initial accumulation on the ground will melt before it starts to stick.
Snowfall rates are expected to be moderate, from 1 to 2 inches per hour, with heavier bands mixed in at times.
Winds are forecast to gust 20 to 40 miles per hour, blowing the snow and reducing visibility. However, due to the wet nature of the snow, blizzard-like conditions were generally not expected and should only be short-lived if they occur at all.
Coastal flooding was also expected to be an issue from Washington, D.C., to Delaware to New Jersey and Long Island and then from Cape Cod to Boston and Portland.
-ABC News' Kenton Gewecke