More than a dozen counties in New York and New Jersey were under a state of emergency on Saturday morning as an intensifying nor'easter approached, threatening the nation's most densely populated corridor with strong winds, heavy rain and flooding. The center of the storm was forecast to linger along the New Jersey coast and move north toward Long Island through the weekend, before turning northeast early next week, the National Weather Service said in an advisory on Friday afternoon.

The Weather Service has issued coastal flood warnings effective until Sunday evening for northeast New Jersey, southeast New York and the Massachusetts coast, including Cape Cod and Nantucket. Up to three feet of flooding was forecast in waterfront areas in New Jersey and New York, with water levels likely to peak on Saturday morning. Gusts stronger than 50 miles per hour were expected to hit eastern Long Island and southeastern New England, potentially causing power outages and felled trees, the Weather Service said.

Several airlines, including United, Delta, American and Southwest, have told customers to keep a close eye on the shifting forecast. More than 370 flights into or out of the country were canceled as of 6 a.m., according to the flight tracker Flight Aware. The Federal Aviation Administration is predicting delays at the major Northeast airports for any flights not canceled.