BC Zone Observation Report
Saturday, May 11, 2019 at 12:00 AM
NE aspect off Parnassus's north ridge ~12,800 feet feeding into the Northface Drainpipe.
Calm below ~11.5-12K feet, high winds above 12k. Mostly clear skies with limited sun affect on Parnassus due to mountain wave cloud persisting through 9:30 am. Wind was consistently pushing from the west with sustained gusts of at least 25 knots. The wind chill was very significant at times.
Above treeline, new snow ranged from 1 inches to 6 inches. No cracking or wind crusts were observed while there were a few isolated spots where the snow had not bonded to the old snow along the skin track, but there did not appear to be any weak layers present.
My partner and I climbed the route together to the top of the ridge leading to the summit. We navigated to the top of the ridge through the left flank of the cornice. From there I decided to descend into a wind-protected spot next to a rock just below where we separated. I utilized that vantage point on the NE aspect to take pictures of my partner descending from the summit to skier's right of the cornices where others had previously dropped before him. After his descent, my partner stopped further down the face and had eyes on me as I dropped down. I had intended to follow the fall line heading skier's left away from the cornices to manage any possible slabs. I slowly cut across the face a few times to see how the snow reacted before initiating my descent. On my second turn I had hit a pocket of firm snow which released and on my third turn my tail washed out to skier's right so I ended up in switch mode for a few seconds before recovering. As soon as I recovered, I got swept from underneath by the slide. I attempted to move my board, but it was locked into the heavy, moving snow so I kept my hands free and after about 15 seconds the slide came to a stop and I was able to get up and ride out without injury. A few things to note - the forecast discussion on Friday afternoon did not note any wind slab concerns. These concerns were added to Saturday afternoon's discussion. Above treeline, the temperatures seemed very cold for the forecast and the wind was much stronger than forecasted. It was 24 degrees at the Ruby Gulch trailhead at 11 am (barely changed in 4 hours). The main takeaways from today's free lesson was to put much more consideration into the current weather observations and how they may lead to wind slab formation throughout the day.
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Backcountry tourer caught/carried in small wind slab avalanche. North to northeast facing terrain, Front Range May 11, 2019.