The north-east US coast is braced for a big snowstorm that has already caused hundreds of flight cancellations.
The storm is set to cause power cuts and transport chaos as it arrives from the Great Lakes and brings blizzards to parts of New England on Friday.
It is expected to peak on Saturday morning east of Cape Cod.
Schools have already been closed in Boston, where sustained strong winds are set to exacerbate heavy snowfall - as much as two feet in some areas.
The National Weather Service said the combination of two weather systems from the polar and subtropical jet streams would produce a "potentially historic" storm, with weather warnings extending from New Jersey to Maine.
Winds of up to 35mph (55km/h) with significantly stronger hurricane-strength gusts were expected to create deep drifts.
Airlines have already cancelled hundreds of flights across the region.
In Boston, Mayor Thomas Menino urged businesses to consider allowing staff to stay home to reduce the risk of commuters getting stranded.
"We are hardy New Englanders, let me tell you, and used to these types of storms," said Mr Menino.
"But I also want to remind everyone to use common sense and stay off the streets of our city. Basically, stay home,"
In New York, where memories of October's Hurricane Sandy are still fresh in the mind, the famous Staten Island ferry has had its schedule reduced. While schools remain open for now, residents are being advised to prepare for the worst.
"Due to potential power outages and transportation difficulties, New Yorkers are advised to stock up on potential supplies, including medicine," said the city's mayor, Michael Bloomberg.
With up to a foot of snow expected over the next two days, Mr Bloomberg said snow ploughs and 250,000 tonnes of salt were being readied for use.
