Snowstorms ground air travel in Northeast

A powerful winter storm system will again snarl air traffic in the Northeast on Thursday, canceling hundreds of flights as travelers try to get home after the Christmas holiday.

Winter storm advisories are in place from central Pennsylvania to Maine, with snow accumulations of up to a foot expected by Friday morning, according to CNN meteorologist Bonnie Schneider.

A tracking website said many flights across the country have been called off for weather and mechanical reasons. According to FlightAware.com , more than 400 flights have already been taken off the schedule for Thursday. That's in addition to about 1,780 flights canceled Wednesday.

US Airways grounded 376 flights, according to spokeswoman Michelle Mohr.

"That is out of a total of 3,200 flights on this busy traveling day," she said Wednesday.

United Airlines called off 225 flights while Delta Air Lines had 200 cancellations, officials said.

American Airlines canceled 500 flights Wednesday, spokesman Matt Miller said.

About 375 of those flights were at Dallas/Fort Worth International Airport, where more than 1,000 passengers spent Christmas night after their Tuesday flights were called off, CNN affiliate WFAA reported.

"(Tuesday's) rapid snowfall, ice and winds required us to implement a deicing program and severely hampered our ability to safely service aircraft as we normally would," airport spokeswoman Cynthia Vega told the station.

Philadelphia International Airport had some arrival delays of more than four hours Wednesday, the Federal Aviation Administration said.

Airports in the New York City area reported delays of almost three hours on Wednesday.

Travelers are advised to check before leaving home to see if their flights are postponed or canceled.