Washington:
A massive snowstorm put a crimp in travel plans for thousands of US air passengers and drivers, not even sparing President Barack Obama, who faced travel delays upon returning from a day trip to the US Midwest.
Hundreds of flights were cancelled and schools closed because of a snowstorm that was expected to dump up to 12 inches (30 centimeters) of snow on US east coast cities on Wednesday night.
The snowfall forced Obama to alter his travel plans. He had to use a motorcade -- instead of his helicopter -- to get from Andrews Air Force Base to the White House. Obama had returned to the Washington area from a trip to Wisconsin at 4:45 pm.
Snow created treacherous road conditions that caused several cars to skid off the road or become stuck in the snow, slowing the presidential motorcade, which made it to the White House at 5:58 pm.
Meanwhile, several hundred flights were canceled late Wednesday -- with more cancellations expected on Thursday - as heavy snow forced Washington's airports, Dulles International and Reagan National, to close their runways for several hours.
"Travelers should call ahead because it will take time for the airlines to recover their schedule Thursday," said Rob Yingling, spokesman for the Metropolitan Washington Airports Authority.
Yingling could not specify a number of canceled flights but each airport handles more than 800 flights per day.
Hundreds more flights were canceled at aiports in New York, Philadelphia and Boston, according to local media reports, which estimated at least 600 in the New York-area airports.
The National Weather Service put the entire Washington-to-Boston corridor under a winter storm warning for "severe winter weather conditions," including wet, heavy snow that caused thousands of power outages in the Washington area, as well as other cities.
The storm warning was to remain in effect until early Wednesday morning .
"Only travel in an emergency," the warning stated. "If you must travel, keep an extra flashlight, food and water in your vehicle in case of an emergency."