More than 1,000 flights were canceled or delayed across the country on a busy travel day

As travelers prepare to fly home on what is expected to be one of the busiest travel days in 15 years, a powerful winter storm in the Midwest and Great Lakes region has caused hundreds of flight cancellations across the country.

As of Sunday afternoon, 6,211 flights in and out of the United States were delayed, and 1,006 flights were canceled, according to flight tracker FlightAware, which provides updates on flight delays and cancellations.

Out of Los Angeles International Airport, California’s busiest airport, six flights were canceled, and 126 were delayed. Inbound flights to LAX were also affected, with 12 flights canceled and 155 delayed. Hollywood-Burbank Airport and Long Beach Airport were also affected with several flight delays on Sunday.

The Transportation Security Administration said in a statement on November 21 that more than 17.8 million passengers were expected to fly from November 25 to December 2, with more than 3 million passengers traveling on Sunday. “We predict that the Sunday after Thanksgiving will be one of the busiest travel days in TSA history,” said Adam Stahl, the senior acting TSA deputy administrator.

While weather is the main cause of delays, some short-term disruptions are expected after the Federal Aviation Administration and the European Union’s Aviation Safety Agency issued emergency airworthiness directives to address software problems on the Airbus A320 aircraft. The recall came into effect after a JetBlue Airways flight from Cancun to Newark on Oct. 30 skidded midair and made an emergency landing in Tampa, Fla., injuring 15 to 20 passengers.

Before heading to the airport, travelers are encouraged to check NASstatus.faa.gov for flight delays, the National Weather Service for weather conditions and airlines for flight updates.