CHEYENNE, Wyo. (AP) — The National Weather Service says a spring winter storm is bearing down on Wyoming.

Winter storm warnings, watches and weather advisories are posted for all but the northwest corner of the state. Up to a foot of snow is possible in some areas Monday and Tuesday. Strong winds are expected to accompany the storm.

The National Weather Service says snow is expected to start in central Wyoming by Monday afternoon and spread to the east by Monday night.

A winter storm warning includes the cities of Laramie, Rock Springs, Casper, Rawlins, Riverton and Lander. A winter storm watch is posted for Cheyenne, Douglas and Gillette.

The storm could provide a last boost to the state's snowpack, which is only 77 percent of normal. It was 70 percent a year ago.