Professional Observation

Observation Details

Signs of Unstable Snow

Key Points

I took a quick after-work tour up Bishop Bowl.

• I stomped on a northeast-facing test slope at 9,000 feet and triggered a small wind slab avalanche.
• I counted at least 7 natural avalanche debris piles in the west-facing chutes off of Table Mountain. These were the result of natural wet loose avalanches that occurred during the early, wet part of the storm. They were mostly small in size (D1-1.5).
• I got isolated cracking and collapsing around 9,500 feet, likely as a result of the new rain crust breaking under the storm snow.
• It rained at least to my high point of 10,400 feet at the start of the storm. There’s a crust that thins from several inches thick below 9,000 feet to just a centimeter thick at 10,400. There’s between 8 inches and over a foot of new snow on top of the crust – deeper with elevation. The top of the new snow was wind-blown almost everywhere I traveled. It seemed as though it rained enough around Bishop that the whole snowpack under the crust got wet, including the basal facets – which I found still moist in a few quick hand pits.
• There was a lot of blowing snow from the peaks. I could always find some east-facing slopes getting intense wind loading.

I stayed below treeline to reduce my chances of triggering a large avalanche. I stayed on low-angled terrain with no overhead hazards and kept to wind-sheltered slopes as best I could. In that kind of terrain the skiing was so good I wished I’d had more time. With the wind-affect, I’d bet the skiing was not only dangerous on steep leeward terrain but pretty crumby by comparison. The descent down the moraine was pretty sketchy and I’m not sure I’d recommend it.