Cool video, and great job by the rescue team, and amazing for such a long burial survival.
Seems the CAIC may still be piecing together an official report but I dug this up from the CAICís website:https://avalanche.state.co.us/acc/acc_report.php?acc_id=497&accfm=rep
Unfortunately I canít link directly to the archived bulletin from the day but a few key points in it:
"Strong, gusty west and northwest winds drifted Friday's snow and added to the wind slabs drifted earlier in the week. Expect to find touchy wind slabs several feet thick. You will find them on most slopes, even open areas below treeline, with the most extensive drifting on north to east to south aspects near and above treeline. Deeper in the snowpack, persistent weak layers remain a concern. The persistent slabs over the weak layers have become stubborn and harder to trigger. If you find the wrong spot you could trigger a very large, destructive avalanche. Avalanches in the recent wind slabs could step down and pull out larger avalanches.Ē
"Snow & Avalanche Discussion
Recent avalanche activity indicate problems at the top and bottom of our snowpack. Over the past week, snowfall and wind have combined to form wind slabs in the upper snowpack. There are old weak layers buried deeper in the snowpack. While getting stubborn, once triggered they produce large or very large, destructive avalanches.
Expect to find touchy wind slabs on many slopes near and above treeline, and some open slopes below treeline. Wind slabs are two or more feet thick, and observers report that they were touchy and easy to trigger. The winds that formed the slab were from the west to the north, so the deepest drifting will be on north, east, and south aspects. Expect to find cross-loaded terrain features on all other aspects, including gullies on westerly aspects. There were periods of gusty valley winds and you will find wind slabs on open slopes below treeline.
The recent wind slabs drifted on top of persistent slabs and deep persistent slabs. The weak layers are facets in the lower snowpack or depth hoar at the bottom. These slabs have become stubborn and harder to trigger, but if you find the right spot, the result will be a large and dangerous avalanche. Avalanche mitigation work on Thursday triggered very large, destructive avalanches (R4D3) with debris piling 12 feet deep. Observers find hard and clean test results. Last weekend there was a large skier-triggered avalanche in the Vail-Summit zone, a reminder that people can still affect the weak layers.
You can trigger one of these large avalanche by starting a smaller avalanche in the wind slabs, or by hitting a thin spot on the side or lower edge of the persistent slab. That makes it easy to move from relatively safe to very dangerous terrain with just a few steps. You should approach all avalanche terrain with a healthy dose of caution, careful evaluation, and a large margin for error.Ē
The aspect they were on was East Facing at tree-line... while it hasnít been declared human triggered yet, and may not be, that choice of terrain given these conditions... well, very glad someone survived...