'Snoverkill' slams eastern USA

A second major snowstorm in less than a week has struck the eastern United States, paralysing the US capital, shutting down the federal government and forcing school closures from Virginia to New York.

The National Weather Service (NWS) forecast that the storm, dubbed "Snoverkill," would dump up to 36cm of fresh snow on the mid-Atlantic region.

This comes on top of the 91cm of snow from the weekend's powerful blizzard, much of which remains on the ground.

Federal government offices in the US capital closed on Wednesday for the third straight day, while local schools prepared to remain closed until next week.

Even in New York City, Mayor Michael Bloomberg ordered schools closed for the day.

The National Weather Service (NWS) issued a blizzard warning for the Washington-Baltimore area lasting nine hours.

It warned of heavy snowfall and winds of 32 to 48km/h, with even more powerful gusts.

The NWS in an advisory said blowing and drifting snow would produce blizzard and white-out conditions, making travel extremely dangerous.

"Do not travel," the advisory read.

It also issued a blizzard warning for New York in effect until early Thursday morning.

Thousands of homes were still without power in the Washington-Baltimore metropolitan area after Friday and Saturday's massive snowfall dubbed "Snowmageddon".

Strong winds expected to accompany the second storm could also mean further power outages.

Snow-weary residents have since scrambled to get a sense of normalcy, digging out, stocking up on depleted groceries and clearing their streets from fallen trees and branches.

But even before the storm hit, many secondary roadways remained treacherous, with piles of snow and near-invisible black ice.

Harried commuters in the mid-Atlantic states struggled to dig out buried cars and trundle to work on Tuesday on icy roads, while subway users in the US capital suffered long waits despite the relaunch of suspended above ground services.

But just hours after the first new flurries began to fall, Metro said subway service would be limited to underground only stations until Thursday, while transit officials cancelled bus and shuttle service.

Most of the 230,000 federal employees in the Washington DC area were off work, costing an estimated $US100 million ($A113.9 million) a day in lost productivity. Some government offices including the White House, parts of Congress and some agencies however remained operational.

Washington, Virginia and Maryland all declared emergencies, allowing them to mobilise the National Guard to help cope with the unusually severe winter wallop.

No flights were expected to take off from Washington's Reagan National and Dulles International airports on Wednesday, the Metropolitan Washington Airports Authority said.

Airlines operating out of New Jersey, Philadelphia, Baltimore and Chicago also reported cancellations and delays.

The government-owned rail corporation Amtrak said it would operate limited service along its money-making Northeast corridor on Wednesday. In addition to snow, the rail service was also battling downed trees and power lines.