November 28, 2020
November 29, 2020
Zone or Region:
Bagley Basin -> Herman
Did you trigger any avalanches? Yes
Was it intentional? No
Size 1: Relatively harmless to people
A D1 windslab was triggered by skiers above our group as we ascended the final pitch from Mazama Lake to the col South of Mt Herman . 4-18" crown, 35' wide, 50' long. It ran about 150'. The trigger point was about 50' above us where the slab was only about 4" thick. The skiers right flank of the slab broke at our bootpack and at the feet of the last person in our party. 15' shooting cracks were observed lower on the slope prior to the avalanche and hand sheers returned clean planar results at about 8-10"
A minor miscommunication between the groups led to this incident. Our group was ascending through a heavily windloaded section and had initiated a few shooting cracks. The group above us had transitioned and was asking if we were in a spot that was safe for them to descend. We tried to communicate that we were not and they misheard us and began to ski. The second skier triggered a slide that propagated down to our party and broke immediately next to us, with the bootpack serving as the flank to disconnect it from the rest of the slope. It was a small slide with minimal consequence but it was a perfect example of the hazards that come with the crowds in popular zones like Baker, Stevens, Snoqualmie, and Crystal. It's worth noting there are a lot of folks out in the mountains right now and whether you are above or below another group, you should be communicating thoroughly and clearly about your plan to avoid folks skiing on top of each other. The windslabs were thin today but a little bit more snow over night and this miscommunication could have been a burial or injury rather than a close call.
Apologies for the bad photo...
Did you observe any avalanches? Yes
Size 2: Could bury, injure, or kill a person
Bagley Basin, just below the prow. There appeared to be a small crown immediately below the cliff face that ran to almost to the valley bottom. Probably D1.5 with a 8" crown. Looked to be fresh debris although it may have come down in the night. There also looked to be another D1-D1.5 that released below the eastern end of Table Mountain with a similarly sized crown, although we were across the valley so it was hard to tell.
Did you see shooting cracks? Yes, Isolated
Did you experience collapsing or whumpfing? No
Our party observed shooting cracks and a set off a D1 wind slab on a loaded west facing slope on Mt Herman. We observed windslabs in isolated pockets throughout our tour on most aspects other than south. Below Herman saddle on the east aspect, we triggered 4-5 very small (5-10ft wide) pockets of thin (6-8") wind slabs in steep, loaded, or unsupported terrain .