A quick change to colder weather will be accompanied by accumulating snow from the mid-Atlantic to eastern New England into Thursday night.
The cold and snow follows on the heels of record warmth across the Northeast on Wednesday.
The storm will begin with a brief period of rain in some areas, but will quickly change over to snow as temperatures plummet. Initially the snow will melt on paved surfaces. However, that can change in a matter of minutes as the rate of snow picks up.
Despite the recent warmth, snow will fall at a fast enough pace to lead to slippery roads and airline delays as the storm progresses.
Major cities at greatest risk for a period of accumulating snow include Philadelphia, New York City and Boston.
Major travel delays and disruptions to daily activities are likely from accumulations ranging from a slushy coating to as much as 12 inches.
Airline delays will increase exponentially, due to aircraft deicing operations and slippery runways. Flight cancellations will continue to mount.