A massive winter storm was barreling toward Washington on Friday, with the system poised to drop near-record snowfall on the US capital before battering New York and other East Coast cities with blizzard conditions.

The National Weather Service described the storm as "potentially crippling" for a swath of the Northeast, with snowfall exceeding 61 centimeters in the Baltimore and Washington metro areas.

A blizzard watch was issued for New York City and parts of Long Island and New Jersey starting early Saturday. Snow accumulation could reach 30 cm in the region, forecasters said. Southeastern Pennsylvania, including Philadelphia, was expecting 25 cm to 42 cm of snow.

To the south, significant icing was likely for portions of Kentucky and North Carolina.

Millions of residents in the storm's path scrambled to prepare for the weekend weather event, picking stores clean of bottled water, food and other supplies.

Federal employees in the Washington area were told their offices would close at noon on Friday to allow them to get home safely before the snow begins piling up in the afternoon. Public schools were canceled.

The Washington Metropolitan Area Transit Authority, which includes the second-busiest US subway system, took the rare step of suspending operations from late on Friday through Sunday.

The Virginia National Guard said it planned to bring in up to 300 troops to assist in response operations.

Airlines have also canceled Friday and Saturday flights, with many of the 2,200 cancellations for Friday, most of them at airports in North Carolina and Washington.

AP - Reuters