Steamboat Springs The large avalanche triggered by a snowboarder Sunday in North Fish Creek Canyon serves as a dramatic reminder that last week's snowstorm contributed to an unstable snowpack.
Sunday's avalanche, which took place several miles northeast of Steamboat on a steep slope, was remotely triggered by a snowboarder.
He was reportedly about 75 feet away from the slide, which traveled 350 vertical feet. The snowboarder was not caught in the avalanche and there were no injuries.
The mountains surrounding Steamboat Springs received as much as 18 inches of snow overnight Feb. 8. The snow fell on top of an old, weak layer. Since then, unseasonably warm temperatures have condensed the new snow, and several more inches of wet, heavy snow have fallen.
"It took the added weight of the boarder to set it off," avalanche observer Art Judson said. "It was on a very steep slope (estimated at 40 degrees) and it was a pure soft slab. It ran very fast."
Judson e-mailed information received from the snowboarder to the Colorado Avalanche Information Center, and it was posted on the Internet.
Spencer Logan at the Avalanche Information Center said that avalanche danger in Colorado's northern mountains is generally rated "moderate" at or below tree line. However there are increasing pockets of considerable danger, particularly above 8,500 feet and on north to northeast facing slopes in the "Steamboat Zone."
"The danger is inching upward toward widespread and considerable," Logan said. "The most sensitive area is around Steamboat."
Judson maintains contact with a small number of backcountry users who alert him to changes in snow conditions so that he can share them with the Avalanche Information Center. Judson declined to name the snowboarder who told him that Sunday's avalanche involved a fracture that averaged 24 inches deep and 100 feet wide. It took place on a northeast-facing slope at 9,500 feet in elevation.
Logan said backcountry skiers and snowboarders had been able to ride some steep lines in the days preceding the heavy snowfall. That condition can lead to complacency among skiers and snowboarders using the backcountry.
The old snow had become "faceted," Logan said. It's a snow condition backcountry skiers refer to as sugar or recycled powder.
Increasing the possibility of an avalanche is the fact that the old snow crystals did not bond well with the new snow.
"Once you put a load on it, it has no strength," Logan said.
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