YELLOWSTONE NATIONAL PARK, Wyo.- Yellowstone National Park is marking the end of its winter season with the last of the groomed roads closing to snowmobile and snow coach traffic this weekend.

A handful of park roads closed earlier this month. Plowing has already begun in those areas. The remaining stretches of roads will be closed to the public at 9 p.m. Sunday.

If snow removal takes place as scheduled, the first park roads will reopen to automobile traffic beginning April 17, with staggered openings continuing through subsequent weeks.

The schedule is dependent on weather and is subject to delays or changes.

Yellowstone spokesman Al Nash tells the Jackson Hole News & Guide ( ) that it's a major effort to open more than 320 miles of road in addition to pullouts and parking areas.