This post has been updated June 6th, 2011. A new report from Colorado Avalanche Information Center reveals further details of this tragic accident. This photo, below,
posted originally over at CAIC, shows the crown.
Two bright stars in the ski community were extinguished earlier this week when Kip Garre and Allison Kreutzen were killed in an avalanche on Split Mountain near Bishop, CA. Local friends from Squaw joined SAR efforts, locating the two skiers at the base of Split Couloir amidst fresh debris Wednesday. Check out the full article at powdermag.com.
This story saddens me. While I don’t know many of the details, nor am I familiar with the avalanche conditions of the area, I do know this: the Sierra Nevada’s snowpack is well above average and the two were killed while climbing up Split Couloir with the intention of skiing it.
Obviously their timing was wrong.
And timing is everything when traveling in avalanche terrain. While avalanches may seem unpredictable and precarious, in my experience as an avalanche professional, they are not.
Every snowpack is different.
A maritime snowpack (found in the PNW and the Sierras) usually experiences direct action avalanches. These are slides that occur from recent snow. The Cascades and Sierras often see huge snowfall amounts. Usually the deeper layers sinter and bond, making the snowpack safer as it grows. The danger lies in the fresh layers. In mountains that can see nine feet of snow in a single week, those fresh layers can be very dangerous indeed.
In a colder, shallower snowpack, such as in the Rockies, deeper layers rot out and become weaker instead of stronger. This deep slab instability can grow worse as the season progresses, each new layer of snow adding stress but no strength to the sugary depth hoar.
Earlier this month, the big slides at Crystal were caused by a little of both. A weak layer, formed by the MLK weekend rain crust was buried in the snowpack. The layer of snow on top of the crust had come in cold, so in the interface between the two layers there was a large temperature gradient. Nature hates temperature gradients. Just like when you are at home and someone (not saying you here, honey) leaves the front door open. Mother nature swoops in to even out the temperature. She brings in cold or warmth or wind or whatever is needed to even out the deficit. She’s consistent that way.
Same thing happens deep in the snowpack. Rain crusts are always zero degrees celsius. Subsequent layers will always be colder, and over time the crust will actually steal molecules from the colder grains, making them rotten and sugary. You end up with a weak, sugary layer of snow sitting on top of a slippery crust. Add to that the weight of several feet of snow sitting on top, and eventually the house of cards comes down.
Knowing about layers and snowpack, even carrying a transceiver or an avalung, or even a float bag, isn’t going to prevent an avalanche. The real problem with predicting avalanches is that they happen in the real world, on undulating slopes, in asymmetrical couloirs, over convexities shaped by wind.
Here’s the secret to understanding avalanches: just because you skied across the top of a slope without incident, or found reassuring results in a pit or even took a turn or two or
watched your buddy ski the slope safely, that doesn’t mean it’s not ripe to slide. When flinging bombs onto the slope, hoping it will slide, I look for the sweet spots. Hit these spots, sometimes invisible to the observer, and a ripe slope with slide.
A sweet spot is shallow, so that the weight of the bomb or the skier can more easily reach the buried weak layer. A sweet spot might be warmer or colder or rockier or just below a convexity. It all depends on that snowpack, that terrain, that slope.
The two skiers on Split Mountain found a sweet spot. They triggered an avalanche that started up high in the couloir and hit them on the way up. I wish this hadn’t been the case. I wish they would have chosen another route or another day or another mountain altogether.
I don’t think people should have to die skiing. I’ve said this before. My job is to prevent that very tragedy, so I take each fatality in the ski industry with a heavy heart. My thoughts go out to the family and friends missing their loved ones.