The CBAC got up to Mount Owen today to investigate yesterday’s slide that caught and carried two skiers as they boot packed up Jenga Chute. The slide broke above the pair near the top of the couloir as they were about halfway up the chute. The area received 10-12″ of snow on the night of November 2nd which fell on a variety of surfaces ranging from bare ground to up to 2ft residual of snow from the few storms that rolled through the Elk Mountains in October.
The avalanche should be classified SS-AF-R2-D1.5-O/G. The slope angle ranged from 37-41º on an ENE facing slope (61º). It ran ~400 vertical feet from ~12,600ft to 12,200ft. Debris width spread about 60ft wide, ranging in depth from 40-150cm deep.
The snow structure of the slab in the couloir consisted of two distinct graupel layers that fell in our most recent storm, capped by a thin windslab generally 3-6″ deep created by light winds during and after the storm; however, the new snow has drifted into 1-2ft deep isolated pockets. The slab failed and ran on a 4cm “pencil+” hard melt freeze crust from the October 12th storm, although it did scour down to rock within parts of slide path. Up to 50cm of 1-2mm faceted grains remained below the bed surface, which will continue to mature/grow in size as the season progresses, likely causing more concerning instabilities in the months to come, in this location and surrounding slopes.
The CBAC would like to genuinely and humbly thank those involved for sharing their experience for the greater awareness of our Crested Butte backcountry community as we plunge into another winter.