Sawatch
AvalancheDylan Craaybeek, Jewel Campbell · Dec 22, 2024 · Sawatch
Snowpack
On most northerly slopes below and near treeline the snowpack is composed of one to two feet of facets that are mostly supportable to skis and snowmobiles but not supportable to feet. On slopes steeper than 35 degrees it was easy to trigger loose avalanches and on sustained, steep slopes any loose avalanches would gouge into older, weak snow from the Thanksgiving weak storm. On the east-facing shoulder of Peak 12174 (east of Sellar Peak) we found the Persistent Slab avalanche problem as we were getting collapses and shooting cracks traveling up to 50 feet away from where we triggered it. The slope was not steep enough to slide but on very small convexities it was easy to walk across the bottom and have the slab fail slide into the skintrack. All of the cracking and collapsing failed on a layer of well-developed near-surface facets up to 2mm large with clear striations and some evidence of small surface hoar grains. The overlying slab was about 5 to 6 inches deep, F to 4F hard (on the hand hardness scale), and the density of the slab was around 175 kg/m^3. On the ridgeline between Peak 12174 and Sellar Peak, the snow was either wind-hardened to the point where ski penetration was <1cm or weak facets down to the ground with very little structure to the snowpack beyond wind-packed snow and facets. We got a large collapse with shooting cracks while snowmobiling back in a meadow that broke on the same layer with a crust across much of the slope but not all of the slope where the collapse occurred.
Avalanche
Observed a couple of large avalanches likely from November 27 and one widely propagating avalanche on the northeast-facing slopes below the ridgeline of Sellar Peak that likely occurred in the last week. It was easy to trigger small loose avalanches on steep east and northeast slopes but we did not travel on any sustained steep slopes to get these loose avalanches to run more than 10 or 15 feet.