On the afternoon of Wenesday December 17, a solo 37-year-old snowboarder was killed in an avalanche approximately 2 miles northwest of Crested Butte. The avalanche occurred in an area known as the Happy Chutes. The soft slab avalanche ran approximately 1500 vertical feet through small trees, over a cliff and into a confined gully. The avalanche was large relative to the path (SS-AR-R4D2-O). The rider was traveling alone and the details of how the accident occurred are not known.
Map of the accident. Fatal avalanche is outlined.
Remnants of early season snows were subjected to relatively warm temperatures in late November & December, leading to a faceted base layer beneath a crust. Surface hoar formed on top of the crust and was buried early in the second week of December when a cold front brought around a foot of snow. In many areas near treeline, this layer consolidated to a thin 4-finger hard slab. On December 10th and 11th another surface hoar layer formed and was buried on the 12th. Between the 12th and 17th, an active storm period deposited another 2-3 feet of snow in the area of the accident with significant wind transport. On the 16th an Avalanche Warning was in place with HIGH danger at all elevations. While the danger remained HIGH near and above treeline, on the 17th the Crested Butte Avalanche Center and the CAIC reported the danger as CONSIDERABLE below treeline. Between the 15th and 18th, at least 6 medium sized avalanches ran in the immediate area of the accident.
Sometime after noon on the 17th, the solo snowboarder ascended a ridge above the Slate River Valley and Peanut Lake. The victim frequently rode this area. With no witnesses, the actual series of event from this point remains unclear.
Search and Rescue efforts were initiated the morning of the 18th. At approximately 4:00 PM on the 18th, searchers found a lone snowboard track off the ridge. The lone track led directly from the ridge into a recent avalanche, which strained through dense trees. Hazardous weather and dangerous terrain hampered the search efforts. On the morning of the 20th a dog team and SAR members were brought to the valley floor, 1500’ below the entrance track. One significant debris pile just reached the valley floor. This debris was from an avalanche in the next path to the north of the entrance track. Searchers found the several pieces of the victim's gear in the path, and the victim was located in this debris pile following an alert from the dog.
Based on clues, the avalanche probably carried the victim through a dense grove of small avalanche-trimmed trees, over a 20-30 foot cliff band, down a tight gully, and finally into a stand of Aspen saplings. It is unclear how the victim came to rest in the next avalanche path over from the initial track entering an adjacent crown. The victim was found lying supine, head downhill, beneath 4 feet (1.2 meters) of snow without his snowboard or pack attached (neither were recovered), his jacket unzipped. The one recovered pole was extended fully. The victim was not wearing a transceiver.
Given the uncertainty of which and even how many avalanches the victim was caught in, the natural avalanche cycle that ran the night of the 18th, as well as the additional foot of snow and strong winds that fell between the accident and recovery, exact avalanche details remain uncertain. The avalanche path above the victim begins at 10,560’ and terminates at the valley floor at 9,000’. The start zone averages 40 degrees, with the track undulating through several benches and steep rolls. Based upon the general snowpack in the area and the other avalanches, the slab is assumed to have been around 2 feet thick, failing on the basal facets. The avalanche was large realtive to the path (SS-AR?-R4D2-O).
View from the Valley Floor. Fatal accident is outlined.
On the morning of the 17th, the CAIC danger rating was "HIGH near and above treeline on N-NE-E-SE aspects. Natural and human triggered avalanches are likely on any slope greater than about 30 degrees on these aspects. The danger is rated CONSIDERABLE on S-W-NW aspects near and above treeline, and CONSIDERABLE over all below treeline." The danger from the CBAC forecast was similar.
Pritchett, 20081220
