BOZEMAN – On Saturday night Feb. 9, at 10:35 p.m., The Gallatin County Sheriff’s Office received a call reporting two overdue backcountry skiers. The skiers had planned on skiing the Blackmore Trail near Hyalite Dam and told a sister to expect them back in the evening.

When they hadn’t returned by 10 p.m., the sister called the Sheriff’s Office. Approximately 30 Search and Rescue Volunteers responded to the call. More than 10 inches of new and wind overnight in the area prevented searchers from doing a complete search that night, but a full-scale search was started at 5:30 a.m. The skiers were located around 8:30 a.m. as they were making their way down the mountain.

The men, one from Big Timber and one from Idaho, reported that at 6 p.m. they triggered an avalanche on a north facing slope near Alex Lowe Peak, southwest of Mount Blackmore. One of the skiers was caught in the slide and was swept down a couple hundred vertical feet. He lost a ski but was uninjured.

The avalanche broke an estimated 300 feet wide and ran approximately 500 vertical, according to the Gallatin National Forest Avalanche Center. The skier triggered the slide near exposed rocks where the snowpack was thin. A pencil-hard wind slab atop facets was the set up that produced the avalanche.

Due to worsening weather conditions, the skiers were not able to return to their car that night. The men were unable to build a fire and spent the night sheltered behind a rock. They began their descent at daybreak.

The skiers did several things right, said Gallatin County Sheriff Brian Gootkin: Letting someone know where they were going and what time they expected to be back and traveling with a partner.

A report on this incident will be available in the next day or two at mtavalanche.com.

“Since Saturday, a foot of fresh snow has fallen in the northern Gallatin Range. This has put additional stress on buried weak layers in the snowpack,” wrote GNFAC forecaster Eric Knoff in today’s avalanche advisory.

A similar situation exists in the mountains around Big Sky, Knoff wrote, noting that a skier remotely triggered a slide on a west-facing slope in Beehive Basin on Sunday.

This is “bull’s eye data the snowpack is unstable. The tricky part about this situation is some slopes have buried weak layers while others do not. There is little consistency as to what slopes harbor buried facets, so careful snowpack evaluation is essential before committing to avalanche terrain.”