A 32-year-old Denver man was killed Sunday in an avalanche while snowboarding near Berthoud Pass, the first such death of the ski season.Grand County Sheriff Rod Johnson said Samuel Raymond Teetzen and two other backcountry snowboarders triggered the avalanche at about 10:30 a.m. on the northwest side of Mines Peak, near the pass.Teetzen was buried in the snow and it took about two hours to recover his body, Johnson said. The other skiers weren't injured.Authorities said that Teetzen was not wearing an avalanche beacon, although he owned one.A group of backcountry skiers responding to the first slide triggered a second avalanche, but no one was caught in it, said Spencer Logan, an avalanche and mountain weather forecaster at the Colorado Avalanche Information Center.Logan said the first avalanche was 400 feet wide, 2 to 4 feet deep and up to 1,500 vertical feet long. The second, which occurred west of the first, was 300 feet wide, but also 2 to 4 feet deep and 1,500 vertical feet long.Logan said the Mines Peak area in Grand County has been susceptible to slides in the past."It's not too early for avalanches," he said. "We've had just enough snow, especially with the snow Friday night."Portions of Colorado's central mountains received over a foot of new snow between Friday and Saturday. Logan said that snow was packed on a much weaker base of older powder."It's like stacking cinderblocks or two-by-fours on Dixie cups," he said. "There's nothing in the snowpack to support that weight."Logan said many skiers, snowboarders and other outdoor enthusiasts don't concentrate on avalanche preparedness until later in the season."People aren't thinking about it seriously," he said. "They tend to turn off their brain until the winter when things look more like the familiar avalanche conditions."Last season, five people died in avalanches in Colorado, he said.