Travelers across the United States got an early taste of winter weather delays on Tuesday when a powerful storm system dropped snow over the Rocky Mountains, causing more than 100 flights to be canceled at Denver International Airport.

Airline operations were also affected by tornadoes in Texas and Nebraska, as well as by a blizzard warning in effect for a large swath of northeastern Colorado and western Kansas, transportation officials told Reuters.

The rough weather is the result of a storm system that originated in Alaska. The storm was set to drop up to 12 inches of snow on the Denver metropolitan area by midday Tuesday, the newswire detailed based on National Weather Service forecasts.

USA Today put the number of canceled flights in Denver at 140 by 9 a.m. Tuesday morning. About 100 flights, accounting for some five percent of the day's schedule, meanwhile, were suffering delays, the newspaper added.

United, Southwest and Frontier waived change fees for customers ticketed to fly to, from or through Denver and some other Colorado destinations on Monday or Tuesday. American Airlines, Delta Air Lines, JetBlue Airways and Spirit Airlines also posted weather waivers for Colorado travel, the newspaper noted. The details of each waiver policy vary by carrier. 

Denver International is the sixth busiest airport in the United States and serves as a hub for United Airlines, Frontier Airlines and Great Lakes Airlines.

The Colorado facility is also one of the biggest bases for low-cost carrier Southwest Airlines, which told USA Today that it had preemptively canceled about 60 Denver departures on Tuesday and that more cancellations were coming because of poor weather near Dallas and Houston.

Denver International handles an average of 1,500 flights per day. The airport will be swamped with full de-icing operations during the storm, meaning passengers should expect extra time on planes prior to departure, local NBC affiliate KUSA reported. Nevertheless, the storm system is expected to clear by 11 a.m. Tuesday, transportation officials predicted.