BC Zone Observation Report
Sunday, April 14, 2019 at 12:00 AM
Moonshine couloir NE aspect descent. Approached by skinning past the couloir and ascending to the saddle just south of summit. Ridge ascent to summit
Started skinning at 830. Sunny and blue skies until about 11 when we started to get low hanging dark clouds that weren't dissipating. Ridgeline between saddle at ~13500 to summit was windy, maybe 25-35 mph sustained west winds. Visibility slowly decreasing from 1130+, snow showers around noon.
- 4in dry light snow on valley floor on top of hard pack. - SE aspect at 13k was heavier than most we saw through the day and hadn't bonded well to the layer beneath, ~6-8 new snow - Bootpack to ridge from 13.4 to 13.6 was deep. 12+ in from the storm wed thru sunday, possibly deeper due to wind loading
Group of 2, frequent partners Day started great with a sunny and somewhat windy skin through the valley. We had discussed potential issues, mainly wind slab and the technical nature of the route. We were in this area last year around may so knew exactly how we wanted to do the approach, what we wanted to descend and a few plan b's. We were discussing and observing wind at the ridge throughout the approach. Lots of snow transport, we were guessing 30+ W winds. However, we also believed the couloir we were aiming for would be mostly sheltered from this wind. We saw what appeared to be some sloughing in the couloir and considered this was a positive because the touchy layers had been naturally shedding (note: we were either wrong on this point or the sloughing hadn't helped enough). The skies started darkening as we booted up to the saddle. We discussed visibility issues and how that would affect the skiing. The forecast hadn't called for storming until later in the day so we assumed it was simply pockets of clouds. The saddle to the summit had sustained winds. When we got to the couloir the visibility was flipping between mediocre and poor. Winds were still relatively sustained and there was some blowing snow at our entrance. At first look it seemed like this wasn't the day for the route. Because we were a bit nervous about the route in general, we thought we should put our skis on before deciding whether to drop. For us, a steep route is easier to gage when actually on skis. Our main concerns were a) wind, b) low vis and c) steep exposed entrance. We briefly mentioned stability/wind slab but dismissed this as a manageable risk. The wind died down momentarily and I decided to start side slipping into the couloir. At first the snow was hard pack / chalky and a good surface for a steep ski. About 15ft in, some soft snow started to show up at the surface. I started moving slowly. Saw a small shooting crack and had a plate about 5x5' and 4 in deep release down the slope directly in front of me. I was pretty nervous at this point but going back up didn't seem to be an option at this point. It felt too exposed of a location to do anything but continue on. I tried to kick in front of me a bit to get some more to slide away, but couldn't get much else to go. I decided to point it for the center of the couloir and get moving quick - in case something went, I did not want to be above the rocks/cliffs. I was hoping if something did release it would be at my feet. I was wrong. As I started into the couloir a slab broke above me and I started accelerating down the couloir with a bunch of snow. This point of the couloir is easily high 40s, might hit 50. I yelled "avalanche" and then was concentrating on keeping my feet downhill. Neither of my skis released as I had my toes locked out. I had an axe in my hand and briefly attempted a self-arrest before realizing it was fruitless. I was in a river of snow. Next I tried some swimming motions and was luckily staying on top. The snow was still moving fast but had at least stopped accelerating. I was eventually able to dig my downhill edge into what I think was the bed surface and shoot off to the side of the slide. In the end the wind slab had carried me about 500ft downhill and I got lucky I managed to avoid the rocks and the top of the couloir and didn't slam into the side walls. I radioed to my partner that I was ok and we were both relieved. Having radios was a huge benefit this day. My partner asked if he should ski the couloir or find another route. I left it up to him but said that the bulk of the slab was probably gone. He dropped into the couloir and kicked off another small slab but wasn't caught. We met back up and made the exit, which was slow because I had lost both my poles. We made some mistakes this day and plan to regroup for a post-mortem in the coming days. There were a lot of human factors that came into play in this avalanche. In retrospect, it's very easy for us to say that we should have obviously gone to a plan b and that there were more than enough signs that we shouldn't have skied the line in those conditions. But in the moment it was not so obvious. It was hard to distinguish nervousness about the ski route and a dispassionate analysis of conditions. We thought we were overcoming fear of the line and suboptimal weather when in reality we were placing ourselves in danger of a wind slab. Additionally, most of the couloir did appear sheltered from the wind as anticipated and had great stable snow. But it was the top 50ft of the route that counted today and that's where the slab had developed.