Some Pit data from Dec 11 and 12, 2013

Post snow pack observations - snowpits, avalanche activity, signs of instability.
splitboarder
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Some Pit data from Dec 11 and 12, 2013

Postby splitboarder » December 12th, 2013, 4:00 pm

Overall on Southerly and Northwesterly slopes, I have observed a shallow, faceting snowpack with low reactivity and an isolated pocket of moderate reactivity on a Southerly slope.

Observations from Dec 11
Some pit results at 11,500 ~S aspect ~35degrees, ~70 feet south of the top shack at AZSB.
CT Easy, Score 7, Q3/Q2 about 7 inches down - windpacked slab on top of a graupal/faceting layer.
CT VeryEasy, Q2 failed upon isolation about 4 inches down - windpacked slab on top of a graupal/faceting layer (same as above)
This moderately reactive slab on top of faceting graupal may not be widespread, and It appears that the biggest issue for southerly slopes is lack of snow...
But I would look for this, if on a southerly slope with good coverage - does that even exist right now in Northern AZ?


Pit data from Dec 12

White Lightning
Image


Sundance
Image
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raisingarizona
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Re: Some Pit data from Dec 11 and 12, 2013

Postby raisingarizona » December 12th, 2013, 5:41 pm

It actually does exist. We skied off of the south side of Core Ridge with incredible conditions the other day and had a huge whoomph under us once we stopped below the powder pitch, there was probably about 3 feet of snow, maybe 4, it was a bit unnerving to say the least. I thought it may be from geothermal heating but maybe not? It really was very freaky. I would think that this weeks warmer weather might take care of that.

raisingarizona
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Joined: November 28th, 2010, 8:01 am

Re: Some Pit data from Dec 11 and 12, 2013

Postby raisingarizona » December 12th, 2013, 6:14 pm

Is there an accessible decoder for pit results on this site? I would appreciate one if not, I'm ok at back country skiing but not so good at reading the pit results, sorry for being uneducated but a decoder could help us learn for sure. Thanks for your postings!

Edit, I just found one of my books so I can decode!
Last edited by raisingarizona on December 14th, 2013, 5:37 pm, edited 1 time in total.

splitboarder
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Re: Some Pit data from Dec 11 and 12, 2013

Postby splitboarder » December 12th, 2013, 6:42 pm

What I saw on a Southerly slope near the AZSB top shack on Wednesday was a layer of wind-packed slab on top of a weaker layer of faceting graupels. Today I found those faceting graupals in the lower Sundance trees on a Southwesterly aspect. See the sundance pit below and look at the 55-60cm layer. however in today it was not very reactive.
Perhaps the other day you found this same weak layer on a southerly aspect at core ridge... Maybe it was wind loaded from the Northerly Monday winds... Glad it all worked out just fine... There is a lot of data that can be gathered and presented so these graphs can get rather dense.

So to decode this thread watch out for a weak layer on southerly aspects!

And to dig in a little deeper.
Data from a couple of tests from the entrance to 7 meadows on a Southerly slope near the AZSB top shack.
    CT Easy, Score 7, Q3/Q2 about 7 inches down - windpacked slab on top of a graupal/faceting layer.
    CT VeryEasy, Q2 failed upon isolation about 4 inches down - windpacked slab on top of a graupal/faceting layer (same as above).

So the CTV Q2 means this baby failed/collapsed and barely started to slide while I was isolating a 30x30 cm column. I didn't even have to tap it. If it had been a Q1 shear quality, then it may have slid out of the column... So perhaps if your collapsing layer had propagated more or had a more planer shear, it could have turned into a real deal avalanche... We are all glad that it did not. just shooting from the hip here. Will try to decode some of this in tomorrow evenings snowpack summary. It is worth noting that I've seen this graupal layer on Norhtwesterly slopes...

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Troy Marino is a splitboarder and on the KPAC board of directors.
KPAC Snow Summary.
Future Guidebook?!

splitboarder
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Re: Some Pit data from Dec 11 and 12, 2013

Postby splitboarder » December 12th, 2013, 11:12 pm

Would be nice to know your aspect and elevation.

zesue
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Joined: October 21st, 2010, 3:12 pm

Re: Some Pit data from Dec 11 and 12, 2013

Postby zesue » December 13th, 2013, 10:00 am

You guys are hitting the ground running this year. Great info, thanks.

raisingarizona
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Joined: November 28th, 2010, 8:01 am

Re: Some Pit data from Dec 11 and 12, 2013

Postby raisingarizona » December 14th, 2013, 12:15 pm

S/SE facing at around 11k to maybe 11,500 I'm guessing. We were on practically flat ground putting our skins on when we heard/felt the whoomph. It's my second whoomph in 12 years of skiing the Peaks, it wasn't cool and it put me on edge for a little while.
Last edited by raisingarizona on December 14th, 2013, 5:40 pm, edited 2 times in total.

raisingarizona
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Joined: November 28th, 2010, 8:01 am

Re: Some Pit data from Dec 11 and 12, 2013

Postby raisingarizona » December 14th, 2013, 12:20 pm

Complacency can be a dangerous thing, I feel a bit stupid for not taking the snow pack more seriously. It has been cold, really cold and it's thin so some continental like behavior is very possible, hopefully it gets warm for the next week or so before we get another storm.


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