The gates will open Thursday for winter traffic at Yellowstone National Park, but it's likely a key ingredient will be in short supply: snow.

In a release park officials said that "beginning Thursday morning, visitors will be able to travel on commercially guided snowmobiles or rubber-tracked snowcoaches between the park’s South Entrance and Old Faithful.   Businesses which normally offer commercially guided snowmobile and snowcoach tours will be temporarily allowed to use either rubber -tracked snowcoaches or wheeled vehicles to transport visitors from West Yellowstone and Mammoth Hot Springs to Old Faithful. Rubber-tracked snowcoaches will be permitted to travel between Norris and Canyon."

"The rest of the interior park roads have too much ice and snow to allow visitor travel by commercial wheeled vehicles," the release went on, "but not enough snow yet to permit commercially guided snowmobile or snowcoach travel."

The five-day forecast is not encouraging, calling for light snow Thursday before clearing skies take hold Friday.

"Additional sections of the park will be opened to commercially guided snowmobile and snowcoach travel as soon enough new snow falls to permit the roads to be packed and groomed for safe oversnow travel," the park release said.

Travel through the park’s East Entrance over Sylvan Pass is scheduled to begin December 22. The road from the park’s North Entrance at Gardiner, Montana, through Mammoth Hot Springs and on to Cooke City, Montana, outside the park’s Northeast Entrance is open to automobile travel all year.

At Old Faithful, the Geyser Grill, the Bear Den Gift Shop, and the Old Faithful Visitor Education Center open for the season on December 15. The Old Faithful Snow Lodge and Cabins and the Obsidian Dining Room open on Sunday, December 18.

The Mammoth Hot Springs Hotel, dining room, and gift shop will open for the season on Tuesday, December 20.   The Yellowstone General Store, the medical clinic, campground, post office, 24-hour gasoline pumps, and the Albright Visitor Center at Mammoth Hot Springs are open all year.