(CNN) A storm system causing severe weather Sunday along the Gulf Coast is forecast to move off the East Coast, turn into a nor'easter and threaten the Northeastern United States on Monday night into Tuesday.

The storm's exact path remains a bit uncertain, but the system will bring precipitation and wind in what will be the third significant winter storm in the past 10 days.

A winter storm watch is in effect for 8.5 million people in New England, including residents of Boston and Portland, Maine. The National Weather Service Boston estimated 6 to 8 inches of snow for parts of Massachusetts, Rhode Island and Connecticut.

Accumulating snow in SNE Mon night-Tue except outer Cape & Islands. Temperatures will play a key role in how much accumulates, even in some of the area covered by the Winter Storm Watch. Pay attention to the latest forecast updates, since these amounts will likely change! pic.twitter.com/OQvnzbAm6Z — NWS Boston (@NWSBoston) March 11, 2018

New York, Philadelphia and Washington are only under a hazardous weather outlook at this time. The next forecast update will come at 8 p.m. on Sunday.