The second winter storm in a week has blown into New York and surrounding states, with intensifying snowfall that has delayed or cancelled flights as thousands remained without power from the last northeaster.
About 20-30cm of wet, heavy snow, some of it accompanied by thunder and lightning, were forecast for New York City and surrounding New Jersey and Connecticut suburbs through Thursday morning.
Gusts could create "near-whiteout conditions" for commuters, the National Weather Service said.
The service bumped up its snowfall estimates on Wednesday morning, with up to 60cm expected in some inland parts of New Jersey, New York, Connecticut and Massachusetts.
The storm will spread with varying degrees of intensity across the northeastern US, from western Pennsylvania up into New England.
About half of all scheduled flights were cancelled at the three major airports serving New York City, according to the tracking service FlightAware.
All schools were closed in Philadelphia, while other schools across the region cancelled classes or shortened the school day ahead of the storm, local news media reported.
This week's storm was not forecast to have the hurricane-strength winds whipped up at times by the storm last week but forecasters say strong gusts of 97km/h and accumulated snow will still be enough to knock down more power lines.
Last week's storm brought major coastal flooding to Massachusetts, killed at least nine people and knocked out power to about 2.4 million homes and businesses in the northeast.
About 100,000 homes and businesses in the region remained without power on Wednesday.
