Steamboat Springs The signs are strongly cautionary for backcountry snowmobilers, skiers and snowboarders thinking about their first big expedition of the winter.
Steamboat Ski Area spokesman Mike Lane confirmed that ski patrollers conducting routine avalanche control work at Mount Werner on Thursday deliberately triggered slides that broke to a depth of 3 feet. Lane said the avalanche work was being conducted between the East Face and Chute One trails. Uncontrolled avalanches are very rare at the ski area.
Scott Toepfer of the Colorado Avalanche Information Center filed a report on information he received from the Steamboat patrol. He said the avalanches broke on slopes steeper than 38 degrees that face northeast at about 10,600 feet. They were up to 200 feet wide.
They were notable for the way they were triggered.
"Some of the slopes did not release with explosives, then later fractured with ski cuts," Toepfer said. "These are indications of a tender and tricky snowpack."
He added that similar conditions could be encountered on slopes that face northwest, north, northeast and east. The old snow on those exposures is weak, Toepfer said, and skiers don't necessarily have to be on a wind drift to release an avalanche. He rates the danger on those slopes "considerable." Elsewhere it is described as being moderate.
"More snow is headed to the Steamboat zone, so watch for an increasing danger over the next few days," Toepfer warned. "Although the snowpack is tender, it is not very deep. If you get caught in a slide, there is a good chance of getting trundled through the rocks and bushes."
Retired U.S. Forest Service avalanche expert Art Judson of Steamboat Springs said delayed avalanches like the ones encountered by the ski patrol this week are called "post control" avalanches.
"The presence of post control avalanches should warn backcountry skiers that stability information from standard tests will be less reliable than usual," Judson said. "The second, third, or the last skier to cross such snowpacks may be the one that gets caught, while the first person might cross without incident. Skiing or snowmobiling on slopes less than 30 degrees may add some protection against taking a ride or being buried."
Duncan Draper of the Steamboat Ski Patrol told Steamboat tv18 on Friday that none of the control gates that allow skiers to leave ski area boundaries have yet opened for the season. He urged people not to ski the backcountry without a shovel, avalanche probe and transmitter.
"It doesn't do you much good if you are the only one in your party who has that equipment," Draper said. "And it doesn't do much good if two people have it, but don't know how to use it."
Friday morning, the National Weather Service in Grand Junction forecasted that Rabbit Ears Pass could accumulate an additional 8 to 16 inches of snow by this morning. The Natural Resource Conservation Service reported that the settled snow depth at the West Summit of Rabbit Ears stood at 27.2 inches on Friday, up from 16.6 inches on Dec. 1.
The forecast model that Toepfer consults indicates the low pressure trough connected to the ongoing snowfall could sag to the south, meaning areas south of Steamboat will get more snow over the weekend.