Yellowstone and Grand Teton national parks will open for the winter as planned Monday, but will limit some winter activities such as snowmobiling and trail grooming because of low snowfall amounts.

News of the opening comes as a winter storm promises to drop snow throughout the region. Between 12 and 20 inches of snow is expected in Yellowstone over the weekend, with lessor amounts expected in Grand Teton.

Absent significant new snow, Yellowstone officials plan to open the park to outfitters with rubber-tracked snow coaches. From the west and north entrances, the park could also allow outfitters to use vehicles with snow tires and chains to shuttle visitors to Madison and on to Old Faithful.

Snowmobiles and snow coaches with metal cleats or ski steering will not be allowed in Yellowstone until the park receives more snow.

“The snowpack throughout the park for the present is fairly light,” Yellowstone spokesman Al Nash said.

Nash said it isn’t unusual for Yellowstone to start the season with limited snow cover. “Its a challenge we face every winter,” he said.

In Grand Teton National Park, officials have opened most areas for skiing and snowshoeing, including Teton Park Road for hiking, snowshoeing and skiing. Crews will not begin grooming the Teton Park Road until more snow falls.

“Until we get substantial snow accumulations on the park road we won’t be grooming it,” said Grand Teton spokeswoman Jackie Skaggs. “It could damage the grooming equipment and also the road. That doesn’t mean people can’t go out there and make their own track.”

Dogs are permitted on the Teton Park Road and the Moose-Wilson Road but must be restrained with a leash no longer than six feet. People are also reminded to clean up after their pets.

Skaggs said the Grassy Lake Road is currently open to winter travel, but the road currently has only about a foot of snow. This winter, 50 machines a day are allowed between Ashton, Idaho and Flagg Ranch. Machines must use the best available technology when leaving from Flagg Ranch, but not the Idaho side. Snowmobiles for ice fishing will be allowed on Jackson Lake once the ice gets thick enough, which will likely occur in mid-January.

Skiing, hiking and snowshoeing are allowed throughout most of Grand Teton National Park during the winter including flagged trails on the Taggart Lake/Bradley Lake loop, the Death Canyon/Phelps Lake overlook and elsewhere.

The few exceptions are areas that have been closed to protect wintering wildlife including the Snake River flood plain from Moran to Menor’s Ferry and the Buffalo Fork River flood plain within the park boundary. Backcountry skiers should stay away from Static Peak, Prospector’s Mountain and areas of Mt. Hunt. Detailed maps are available at the Craig Thomas Discovery and Visitor Center.

Starting Dec. 26, the park will begin ranger-led snowshoe hikes in the woods behind the visitor center. “It’s a really interesting, different way of getting out with a ranger and learning about winter ecology,” Skaggs said.

A single day pass for Grand Teton during the winter is five dollars.