In October of 2009 the snow started to fall in the mountains. And then, it stopped. November, aside from some intermittent and minor storms was a dismally dry month in the mountains. Good for bike riding. Bad for skiing. And it wasn’t just bad for skiing at that time. Rather, it was bad for skiing generally. That is, the entire ski season is being effected by those early storms, and the rotten, faceted snow that resulted.
What is faceted snow? In short, it is snow crystals that have changed, due to temperature gradients within the snowpack, from being round and cohesive, to being angled and separated. The result is a sugary, crumbled consistency , that sort of snow that falls to pieces in your hand. When such a layer of snow forms at the base of a snowpack, near the ground, it is known as depth hoar. And depth hoar is a primary cause of avalanches.
That sugary, rotten layer of snow is overloaded with the heavier, rounded, creamy powder that we all love to ski. A steep slope then becomes something akin to a heavy cardboard box sitting atop a stack of standing dominos. It might hold, but only just. The slightest additional weight (new snow, wind deposited snow, or a human) collapses the snow, and in the process unleashes its stored energy, sending an avalanche down the mountain.
It’s Avalanche 101.
And it’s what is plaguing the Wasatch Mountains in the winter of 09/10.
The persistence of the weak buried depth hoar is causing an ongoing avalanche cycle. Because our storms have come in short violent bursts this year, rather than consistent snowfall throughout the winter, that weak layer is constantly being catastrophically overloaded. In other words, our weak and shallow snowpack is remaining such partly because slopes continue to slide. And when they go, they are failing all the way to ground, causing massive and deadly hard slab avalanches.
What does it mean?
It means that so far, backcountry skiing has been an exercise in patience, self control, and conservative decision making. It also means that, as The Junkie noted, those wonderful and beautiful lines through the open bowls and the cirques and the star-scraping peaks are simply too dangerous to ski. It also means that unless we experience a complete anomaly of storms –small, consistent, and daily– that nothing will change. That persistent weakness will persist until the suns of summer melt it away, sending it to the snow hell it belongs in. This is not to say that I have not enjoyed the skiing thus far. The aspen glades and the low angled slopes are still enjoyable. And anyway, the downhill is only half the reason I venture into the backcountry.
But missing those fantastical days of smoke and powder does start to wear away at ones dawn patrol motivational matchbox. And it also becomes a sobering realization that skiing wild snow comes with inherent risk. Which, I must admit, is part of the attraction of the backcountry. I am no thrill seeker, but learning how avalanches work, and how to avoid them has become something of an intellectual and athletic hobbyhorse. Something I hope will lead to a long career of safe and enjoyable out-of-bounds skiing.
During the avalanche class I took back in December, I had a chance to dig down into the depths of the snowpack. I laid eyes on the depth hoar, grabbed handfuls of the stuff and watched in nerdy horror how it crumbled in my fist. At that time the class thought, or at least hoped, that the effects of that snow would taper and disappear as the mountains filled with famous Utah snow, that Greatest Snow On Earth. Instead, that shallow layer of rock salt is still holding much the backcountry hostage. And probably will throughout the rest of the winter.
Which all makes for an appropriate opportunity to become acquainted with the new addition to the arsenal.
Thom P.February 2, 2010
Like the new look of the site. Very nice!
Grizzly AdamFebruary 2, 2010
Jonnie JFebruary 2, 2010
Hey nice picture. I wish we could stand atop that bowl this year and let it rip. AF Canyon was good on Saturday. There are some good lines over there with a pretty low angle. I think I may be headed there some more this year.
Our Benevolent CaretakersFebruary 10, 2010
[…] are, as I have written, wreaking havoc in the Wasatch mountains this year. It’s an unusual snowpack, more […]
Persistent, but DifferentFebruary 22, 2010
[…] of the Wasatch snowpack continues to cause problems in the backcountry. The depth hoar that was so deadly a month ago has mostly, but not entirely bridged under the weight of new snow. However, I would not […]