The storm is due to form Friday off the coast of the Carolinas and rapidly strengthen as it moves north up the East Coast overnight into Saturday.
Blizzard warnings Friday cover 4 million people in coastal areas from Maine to Massachusetts and from New Jersey to Maryland. Whiteout conditions will make travel difficult to impossible, the National Weather Service predicts. At risk of blowing snow due to high winds are Portland, Maine; Boston; Atlantic City, New Jersey; and Ocean City, Maryland.
“Powerful winter storm to produce significant impacts across parts of New England and coastal Mid-Atlantic/Northeast on Saturday,” it said. In a blizzard, snow is joined by winds gusting over 35 mph for more than three hours, creating visibility of less than a quarter mile.
The forecast also includes:
• Eastern Massachusetts, including Boston, could see between 18 to 24 inches of snow combined with wind gusts up to 70 mph, forecast models show. Two to 4 inches per hour could fall in the city, with conditions due to peak Saturday between 8 a.m. and 5 p.m. Similar snow total and wind predictions are in place for Rhode Island.
• The Philadelphia area in eastern Pennsylvania is expected to get 4 to 11 inches of snow, with a winter storm warning in place from 7 p.m. Friday to 7 p.m. Saturday. Up to an inch of snow an hour is possible, along with gusts of 35 mph. Similar conditions are expected in the Dover, Delaware, area.
• In Washington, DC, snowfall could be 1 to 3 inches, with higher amounts in some parts and conditions due to peak Friday between 4 and 9 p.m.
Snow, wind and coastal flooding to slam Northeast
The storm is expected to unleash a double whammy of heavy snowfall and strong winds throughout parts of the Northeast, but the exact impact across the region remains in question.
“This storm is likely to strengthen at a rate, and to an intensity, equivalent to only the most powerful hurricanes, so the high-end potential of this storm cannot be overstated,” CNN meteorologist Brandon Miller said. “But with nor’easters, like in real estate, it will all come down to location, location, location.”
“Coastal flooding is a concern thanks to astronomically high tides on Saturday,” the weather service office in Boston said. “The combination of strong northeast winds and high seas will bring storm surges that, if coinciding with high tide, would lead to minor or moderate coastal flooding.”
The difference in storm timing — even as few as six hours — would make a massive difference in impact on coastal flooding and erosion concerns.
New York City forecast remains uncertain
A European forecast model shows New York City on the edge of the snow-or-no-snow divide but still predicts a heaping pile of snow. The American model shows nearly nothing for the city. A third model indicates a foot or more of snow.
And direction is playing a vital role in this storm’s projection, too, CNN meteorologist Chad Myers pointed out.
“It’s like a bowling ball going right down the middle or slightly off-center. You can get a 7-10 split or a strike with only an inch difference,” Myers said. “I think the models will come together as we get closer to the event.”
CNN’s Judson Jones and Robert Shackelford contributed to this report.