BC Zone Observation Report
Sunday, November 3, 2019 at 12:00 AM
Cameron Pass, South Diamond Peak, Medicine Bow Mountain Range
AOI for snow pit analysis: lookers-right of South Diamond peak, known as Ptarmigan. Recent avalanche location: "Avy Alley" or "The Gash"
Clear conditions for most of the morning, temperatures ranging from 22 degrees Fahrenheit at 10,200ft, and 17 degrees Fahrenheit at and above 11,000ft. Winds blowing from the West at 15-20mph, gusts near 30mph on N/NE/E aspects. Temperatures slowly warmed to 23 degrees above treeline, with thin cirrostratus and small lenticular clouds forming to the southeast by 1200; visibility was not affected.
After the recent storms that hit the Northern Colorado mountains, approximately 9 inches has accumulated on top of weak facet layer at and above 11140ft. Snowpack has been impacted by extensive wind-loading over the course of the past 3 days, with increasing amounts of solar radiation and cloudless evenings and days. Top layer has toughened up and showing instability based on its bonding with the weak facet layer below it. Shooting cracks are noticeable when ascending across all wind-drifted slopes above 19 degrees. Snowpack depth varies from 40cm below and at-treeline to 80cm above treeline. Some above-treeline NE aspects are 90cm in depth.
Located on the left-center face of South Diamond Peak, known as "Avy Alley" or "The Gash". A prominent and steep, NE facing gully known for heavy amounts of wind-loading and propagated rocks that act as trigger points. Skier-triggered avalanche likely occurred on 11/1/2019. A second avalanche was also triggered to the right of the gully, most likely at the time the skier exited the slide. Ski tracks are visible at the top of the gully entering, and then quickly exiting to the right; most likely causing the slide to occur. The slide within the gully traveled roughly 400 feet from the crown. I did a beacon search to insure no one was caught/buried; I did not pick up a transmitting beacon signal from the two slides. D1 R1