A record number of avalanches were recorded by the Gallatin Avalanche Center this winter, according to an annual report released by the 20-year-old center recently.

The 87 avalanches in the Gallatin National Forest killed three people: an ice climber was "swept to his death" in Hyalite Canyon on Dec. 10, a snowmobiler was buried and killed outside Cooke City on Jan. 3 and another snowmobiler was buried and killed April 14 on Buck Ridge, according to the report.

"It was the most active avalanche season in our history," director Doug Chabot said in the report's introduction. "We even had slides on Peets Hill and the Moonlight Basin golf course."

Chabot said below zero temperatures in December turned much of the snowpack into weak, "faceted depth hoar," which avalanched all season. The avalanche center did not issue a "low" avalanche danger rating the entire winter.

Along with the three deaths caused by avalanches, 21 people were caught in avalanches this winter and nine people were partially buried. Skiers and snowmobilers triggered most of the avalanches.

In the 2008-2009 winter, the Gallatin National Forest Avalanche Center recorded 45 avalanches that killed three people, all of them snowmobilers, according to the report. The deadliest seasons since the avalanche center began keeping records were 2000-2001 and 1997-1998. Four people were killed in avalanches in both winters.

The avalanche center continues to grow in influence. On average, 3,534 people per day read or heard the avalanche advisory, a 9 percent increase.

This season also saw a huge avalanche south of Bridger Bowl on Saddle Peak.

In the report, the center calls the March slide "unprecedented."

"Although there were people on the slope when it released, miraculously no one was caught or killed," the report says. "We use this incident as a teaching opportunity, which was unprecedented in its scope."

Daniel Person can be reached at dperson@dailychronicle.com or 582-2665.