Steamboat Ski Area officials pleaded for skiers and riders to respect closure ropes Wednesday afternoon after someone triggered a substantial avalanche to riders' left of Chute 3 on Mount Werner.
No one was injured in the slide, which is thought to be the first avalanche within ski area boundaries in more than 30 years.
Ski area spokesman Mike Lane said he was particularly concerned that the unknown person who apparently triggered the slide had ducked a double strand of rope to the side of Chute 3. It was strung there to close off a band of jagged rocks where the slide broke loose.
"We're somewhat upset that somebody jeopardized the safety of others," Lane said. "We need people to respect these closures. They're there for a reason."
The triggered avalanche could have buried an innocent bystander at the bottom of the steep pitch, Lane said.
Ski Patrol Director John Kohnke said the last official report of a skier triggering an avalanche within the boundaries of the ski area was in the early 1970s when a 12-year-old boy was trapped and killed by a snow sluff to the south of Chute 1.
Kohnke said his staff has been unable to identify or interview the person who triggered Wednesday's avalanche. He said that the fracture line at the top of the slope was almost 3 feet deep and that the snow slide carried all of the snow on the rocky exposure to the bottom, 50 to 75 yards away.
Chute 3 was open to skiers Wednesday, Kohnke said, but the closure ropes are strung on the south side of the expert trail to keep skiers and snowboarders away from the dangerous rocks. The ropes were not in place because of any perceived avalanche danger, he said.
Tracks leading into the snow slide suggested the avalanche was triggered by a snowboarder, Kohnke said.
The Steamboat Ski Patrol was made aware of the avalanche when its headquarters at the top of Sundown Express received a cell phone call from an anonymous person reporting that somebody had been partially buried on the side of Chute 3.
"Patrollers responded almost immediately," Kohnke said, but whoever had been temporarily trapped in the snow had dug himself or herself out and left the area. He says the person was fortunate that he or she didn't venture further into the closed area.
"They could have been dragged over the rocks and buried," Kohnke said.
Janet Saller, a snow ranger for the Medicine Bow Routt National Forest, said she intends to work with ski area officials to try to determine who was responsible for triggering the slide.
Kohnke said all three of Steamboat's chutes were closed for about 90 minutes while patrollers "ski cut" the snowpack to check for further instability. They triggered some minor movement near Chute 1, he said. Ski patrollers will be back in the area doing avalanche-control work in the morning, Lane said.
Steamboat received 8.5 inches of relatively wet snow in 24 hours bracketing the avalanche.
Saller said she's concerned that skiers and riders in the area may be underestimating the instability of the snowpack in the backcountry.
The Colorado Avalanche Information Center is rating the avalanche danger "high" across the state. The information center reports that its observer in the Steamboat area has been able to spot numerous slides while on a driving tour of the area.