Front Range
AvalancheIan Peterson · Mar 28, 2024 · Front Range
Weather
Sunny day with moderate temps. Strong westerly winds were blowing snow, scouring many slopes, and little active loading was observed. Evidence of previous wind activity in the terrain was widespread.
Snowpack
We observed a highly variable snowpack. In exposed easterly aspects ATL, it was a mix of sastrugi and scouring down to rocks. gully and bowl features had evidence of previous loading and scouring, and the presence of new wind slabs in terrain was highly variable. Some slopes were scoured down to a crusts, others had a thin, noncontinuous, wind skin/3-4" slab and others had more of a continuous, recently built slab.
Avalanche
As our team moved from Chasm Junction towards Chasm lake, we started to encounter steeper terrain on roughly the Chasm Lake Summer Trail. Many of these slopes faced south and were fully scoured down to a crust from before this week's snow event. As we began to move above Peacock Pool, we started to observe slopes that were more wind loaded. At first, we detected wind loading of super variable depth, from <1" - 4" on slopes. The wind had built P hard slabs on top of ~2-3" of F-4F snow with a robust crust below. Hand shears and test slopes showed that the slabs were not very well bonded, but the lack of connectivity prevented us from turning around, but we had spaced out to minimize our exposure. At the last slope before Peacock Pool, the team regrouped on a scoured section. We discussed whether to drop down and boot up to avoid the steep slopes, or to continue spacing out as we traveled across. We had seen no red flags yet, and decided to space out across the slope. When they were mid-slope, they initiated a crack, that propagated the entire slope. The resulting hard slab that released was ~120' wide, and had a variable crown depth of up to 12". The avalanche broke at the hardness change between the slab and the soft snow beneath it. The skier in the lead was caught and carried ~150', and stopped on the surface on a subtle rocky bench. The avalanche ran to about 100' short of the lake. The skier was able to recover all of their equipment and ski out to the trailhead.