Avalanche!

Nearly 10 years after a skiier was killed on these slides, and after a week that produced nearly two feet of new snow, the Angel Slides on Wright Peak avalanched taking two skiiers for a long, scary ride–both survived without major injuries.  Check out this link.

Avalanches are not common in the Adirondacks due to the amount and type of snowfall, and the inaccessability of many of the slides.  The reality remains though that there are slides between 25 and 40 degrees slope that recieve significant amounts of snow–if the conditions are right they can avalanche.

Due to the unprecedented nature of this event I decided to visit the Angel Slides and see the aftermath for myself.  The newspaper pictures don’t do it justice–this was a big one–the two skiiers are truly lucky to be alive.  I’m not sure how long this slide is, but I would estimate 1000′ or more, and probably 300′ across (very rough estimates).  The avalanche released at the top of the slope and was the width of the skiers right portion of the slide.  The skinnier, skiers left slide did not realease, but because it has the same slope and aspect the potential for avalanche is high.

I got to put my Avalanche I skills to action for the first time since leaving Idaho.  About 1/3 of the way up the slide I was able to dig a snowpit and assess what may have caused the slide.  The top 2/3 of the slide is steeper than the bottom 1/3–well in excess of 30 degrees–probably very close to the magic 34 degrees that most avalanches occur on.  The top section released all the way to the ground, and the debris washed over the bottom 1/3 without releasing the snowpack.  Basically this means that where I dug my pit the snowpack was preserved on a slope of 28 degrees.

A couple of standard tests were done to assess the layering of the snowpack and to see if the snowpack can fail.  The snow was 105 cm deep, and a weak layer of sugary snow was found 35 cm from the ground.  During the compression test an isolated column of snow failed (a clean sheer) at the same depth, 35 cm.  Early in the season, some sort of weather event created this thin weak layer that is most likely what caused the avalanche.

So that’s alot of avalanche jargon and stuff many people don’t care to understand.  The take home point is that there is a persistent weak layer near the ground that will not go away until snowmelt begins and water starts perculating through the snowpack.  If in a week from now people thing the danger has passed here in the Daks, they should think again.

This was a great day to see a unique event here in the Adirondacks, with a great ski tour and downhill finish to the car.

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