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Feb 21, 2014, Stemilt Avalanche observation's

2/21/14
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Posted by jtack on 2/22/14 1:22am
I was interested to see what affect the wind event of the 20th had on the snow, so took a quick tour into the Stemilt Basin.  I have not been over that way for awhile, but I was not surprised to see there had been several natural releases, I'm not sure they were related to the wind event, or were part of the earlier storm snow loading.  From what I could see it looked like they slid on the ground contact.  I dug a pit, to see what I could see, the wind built yet another denser layer over soft snow below.  In three column test, two failures occurred in the lower density snow below the wind slab, and one occurred as a sudden collapse  at the ground contact.    I was told that the basin to the SE had a large failure caused by snowmobile's but did not travel over there to look.











Wow - some of those failures look pretty low angle. I'm going out for a look myself to get some exercise and exploring in the valley.

sure looks like our snowpack is hugely variable and complex.

Interesting, you skinned over from the Outback I assume. It would be interesting to take a look at the top after a hike to Microwave. I rarely ski that lower stuff and usually head up and over the bench before I get to that open slope that the ski blaze dumps you out on. I think the folks on snowbikes weren't too far from that spot.

two days later:2-23  Jamie and I looked in from the top.  On the way there, we saw this crown in a popular run off of the Microwave ridge called "last tree" (intentionally triggered by patrol with explosives)


We poked in to the top of Stemilt Basin and sawed off a small cornice to see if we could trigger something; no result.  Then we roped up and jumped up and down on a suspect slope; no result.

We dug a pit and found 100cm of well bonded snow over an ice layer, over 30 cm of sugar.  My column test failed just under the ice layer and Jamie's failed lower, in the sugar, near the ground.  Being with Jamie is like having a personal snow science instructor, I enjoyed every minute.  It was a great day with almost no skiing.  We headed home the way we had come and didn't make any turns in Stemilt. 

Exit through bowl four with a visit to the Patrol's 8 foot crown at the humps.  Wind has blown in snow reducing the visible crown to about half a body height.  Still very impressive.  Here are pics:



It isn't dark out.  I played with the contrast to try to make the snow features visible.  The light was very flat.



and for those with 3 minutes and 49 seconds to kill, here are our attempts at triggering a slide.  We gave it our best, but didn't succeed.

http://youtu.be/E1sOIWcms1s

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feb-21-2014-stemilt-avalanche-observation-s
jtack
2014-02-22 09:22:26