Vail & Summit County
AvalancheDrew Gibson · Nov 29, 2022 · Vail & Summit County
Weather
Cold and stormy. Light breeze and single digits at the trailhead at 0930. Winds at ridge crest were moderate from the NW. Light snow S-1 during the morning. Wind speeds and snow picked up around noon.
Snowpack
Approximately 20cm of new snow overnight. Average snow depth on west aspect BTL 50cm-60cm. The snowpack BLT is weak and mostly structureless. Below treeline, isolated cracking around skis was observed in the new snow. Cracking was not stepping down into the old snow. Isolated collapsing was heard/felt only in areas where the wind had drifted soft snow. Old tracks were still visible but filling in. Near and above treeline snow was actively being transported onto lee slopes. Fresh pillows and cornices were visible. A quick pit showed a mostly soft and deteriorating snow structure with chains of depth hoar forming on the ground. Despite the weak structure of the snowpack test results only occurred at the new/old snow interface. Test results showed the new/old snow interface is weak in shear, and compression and able to propagate a failure.
Avalanche
I remotely triggered two different slides. Both slides occurred just below ridge crest on steep, wind-loaded rollovers. At the trigger point, the surface snow was relatively soft with underlying hard layers. Shooting cracks communicated over 50m across the slope. The distance from the trigger point to the crowns was ~20m. Slab depth was up to 1 meter deep. Due to the nature of the terrain, both slides only ran ~10m.