We rode around the Johnson Pass area to look at the aftermath of a major avalanche cycle following this week’s storm. We saw a lot of very large crowns and debris piles. Some of which looked fresh and had occurred near the end of the storm, while others occurred mid-storm and had since been partially buried by snow and strong winds. We saw crowns a mile wide or wider, and debris piles that were around 20′ deep. We made it to a high point of 2200′ and found around 3.5′ of settled storm snow in our pit at 1700′. We could only find one of the 3 layers of buried surface hoar in the snowpit, and did not get any propagating test results. The stability tests were more of a footnote, and the widespread activity was all the info we needed to be very, very cautious with our route finding today.
We saw two small (ish) slab avalanches on a southern aspect at around 4000' that may have occurred when the sun was out cooking the snowpack this afternoon, but they may have also occurred near the end of the storm. Everything else we saw was from mid-storm.
There were too many very large (D2.5-D3) debris piles to count. Some of the crowns that were still visible were over a mile wide. Multiple avalanches ran to the valley bottoms, with full-grown trees in the debris. A lot of these looked to be a mix between wet and dry snow.
|Cracking (Shooting cracks)?||No|
Widespread recent avalanche activity had us avoiding avalanche terrain and limiting time spent in runout zones.
We were lucky to have some windows of sun in the morning and early afternoon before clouds started moving back in during the afternoon. Winds were light out of the east. Heavy snowfall in the morning down to the road along the Turnagain Arm dissipated by the time we got to the top of the pass.
There was a breakable crust up to around 1300', with wet snow on the surface up to around 1500' and moist snow up to our high point around 2200'. Settled storm snow was around 3.5' deep on a sheltered slope at 1700'.
We could see crusts from 3/2, 3/16, and 3/22, but were only able to identify the 3/2 surface hoar layer in our pit. That interface was 155 cm (roughly 5') deep in our pit.
We did not get any propagating test results, but the widespread avalanche activity was all the information we needed to keep our terrain very low angle. The lingering potential for very large human-triggered avalanches in the next brief window of quiet weather is alarming.