Close call with small avalanche on Andesite Peak.

Location Name: 
Andesite Peak
Donner Summit Area
Date and time of avalanche (best estimate if unknown): 
Mon, 02/20/2017 - 10:50
Location Map: 
United States
39° 20' 59.3772" N, 120° 21' 44.8092" W

Red Flags: 
Recent avalanche activity
Whumphing noises, shooting cracks, or collapsing
Recent loading by new snow, wind, or rain
Obvious avalanche path

Observation made by: Forecaster
Avalanche Observations
Avalanche Type: 
Trigger type: 
Crown Height: 
1 ft
Weak Layer: 
Storm Snow
Near Treeline
7 860ft.
Bed Surface: 
Storm Snow
Number of similar avalanches: 
Number of people caught: 
More detailed information about the avalanche: 

This was a close call incident on a slope that my partner and I had no intention of entering into until I accidentally dropped my ski pole and it slid 15 feet down the slope.

Prior to dropping my ski pole, I had intentionally approached the top of the slope for stability assessment and data collection. The slope angle at the top of the slope was 45 degrees and it quickly decreased to 32 degrees about 15 feet downslope. I kicked at the very top edge of the slope and created shooting cracks 1 foot deep. These cracks connected with steeper terrain about 60 vertical feet downslope to a convex rollover. Along this rollover, an avalanche released with a 1-foot crown that propagated around 200 feet wide. After taking a photo of the initial shooting crack, I gave the cracked slab a few more kicks and it moved no further. I then stepped down onto the top 1 foot of the slab and knelt down to examine the shooting crack I had created. I also dug out and examined the failure layer which was near the base of the storm snow, about 1 cm above a 2 mm thick rain crust at the old/new snow interface. The slab was F to 4F hard. At that time I accidently dropped my pole and it slid about 15 feet downslope.

My partner and I then discussed how to retrieve my ski pole. We discussed tying our cordelettes (ropes) together and attempting to snag the pole but gave that an extremely low chance of success. We also discussed further attempts to make the upper slope avalanche to mitigate the hazard but concluded that the ski pole might be buried in the process. Just leaving the ski pole behind seemed unnecessary.

At this point I rationalized entering the slope to retrieve the ski pole as the most realistic option. I considered that the upper portion of the slope had cracked but not avalanched and that additional kicks had no effect to further move the slab downhill. I also considered that I had stepped onto the very top of the slab to examine the weak layer and the slab had not moved any further. I concluded that the slab was held in place by the friction against the bed surface with extra support from the lower angle portion of the slope immediately below.

I thought about but did not communicate to my partner the possibility of entering the slope on belay. If a deadman style anchor made from my partner's skis had failed and been pulled down the slope with me, it would have left my partner at the top of the slope in deep snow without skis. I also thought about but did not like or communicate the idea of trying to cross the narrow start zone at speed on a ski cut and pick up my pole on the way by. This seemed too difficult in deep snow.

I planned to sidestep/sideslip the 15 feet down to my pole and then exit 10 feet to the south onto low-angle terrain. I quickly communicated this plan to my partner who reluctantly agreed and I began to sidestep/sideslip down the slope on the previously cracked 1-foot thick slab. When I was about 10 feet down the slope, my partner heard a whumpf and the slab cracked again further downslope than it had initially and started sliding as a slab avalanche.

I was caught in a relatively slow moving 1-foot deep and 20-foot wide avalanche. I immediately deployed my airbag and then attempted unsuccessfully to use the handle end of my remaining ski pole to self-arrest on the bed surface. Ultimately, I was carried down a total of 200 vertical feet, over the mid-slope rollover, and onto the bed surface and debris of the lower avalanche. I was not buried. The tails of my skis were crossed but mostly out of the snow. I stood up uninjured with all equipment. Once I got my skis back on the surface I skied out the bottom of the slope. I picked up my ski pole along the way as it had ended up just below me on top of the debris. I exited the runout zone and regrouped with my partner. After deflating my airbag we returned to the top of the slope to begin to analyze what had just occurred.

Lessons Learned and Analysis:

The small size and slow moving speed of the avalanche made it easy to survive without injury. I speculate that without the deployed airbag, some amount of partial burial may have occurred but that full burial would have been unlikely due to how high I was on the small slab and the limited amount of debris.

The main lesson learned was not decide to enter the slope to get the ski pole so soon in the brainstorming process. Time was not a critical or pressing factor. My travel partners in multiple disciplines have previously commented that I am skilled at slowing down and thinking things through during problematic situations. In this case, I needed to slow down even more than I did in order to more thoroughly think things through. Even some low-likelihood-of-success tactics to snag the ski pole would have been worth the time spent before committing to entering the slope which was previously identified as a no-entry zone.

Further brainstorming after the fact between my partner and me raised the idea of using a probe and ski pole strapped together to snag the dropped ski pole. This system would have provided sufficient reach and had a fairly good chance of success. We would likely have come up with this idea if we had not acted so quickly on the idea of entering into the slope. - BS

Avalanche Photos: 
Weather Observations
Blowing Snow: 
Cloud Cover: 
100% of the sky covered by clouds
Air temperature: 
Below Freezing
Wind Speed: 
Air temperature trend: 
Wind Direction: