The U.S. government shut down in Washington today ahead of a fierce snowstorm packing heavy, wet snow that had blanketed the Midwest, leaving thousands without power and forcing hundreds of flights to be cancelled.

Washington could get slammed by its biggest snowfall in two years, with 15 cm to 30 cm expected after the storm moved eastward into the mid-Atlantic states, the National Weather Service said.

The government, already hit by $85 billion in overall budgetcuts that took effect last Friday, ordered 375,000 federal workers in the Washington area to stay home. Major school districts in the area also shut down ahead of the storm, which is packing winds of up to 35 miles per hour (56km per hour).

Airlines cancelled about 1,500 flights, including about 700 at Washington's Reagan, Dulles and Baltimore/Washington airports. About 1,700 flights were called off yesterday as the storm moved across the north central United States.

The heavy, wet snow was expected to bring down power lines and tree limbs. About 54,000 Dominion Resources Inc customers were without power in Virginia, and American ElectricPower Co Inc and FirstEnergy Corp reported 5,000 customers in West Virginia were in the dark.

The National Weather Service forecast heavy rains on the Atlantic coast. The New Jersey Office of Emergency Management said it was monitoring a coastal storm expected to bring heavy rain, high winds, snow and coastal flooding through Friday morning.

The weather service said the system dumped 18cm of snow on Chicago's O'Hare International Airport by the time the winter storm warning had expired at midnight Tuesday night, making it the city's biggest snowstorm in two years.

During the evening rush hour, wind-whipped snow reduced visibility to less than half a mile (0.8 km) and caused delays on roads.