Yodlin 061223

A most interesting day out there.
Two noteworthy issues, first was a tempature gradient.
At 10 CM -3.9 C
At 20 cm -5.7 C
After that it became more normalized 0.2-0.3 C every 10 cm

The second and perhaps more important was a clean, high quality shear at 160 cm, yes that was 160 cm with a CTM with a score of 19. Now that is scary and pretty remarkable. That layer seems to be pretty well bridged right now, but if something changes it could get really ugly, really ugly. I would suspect that is is isolated in pockets and it would take a huge warming cycle to make this happen.


I am still getting the hand of the new Snowpilot software and there are a few errors that I need to figure out how to fix. I also have a few wish lists in terms of what I would like to see this software do. But it is a hell of a lot prettier than my fieldbook.

Rutschblock explained

Until last week, I had neglected to include a Rutschblock test.
First and foremost, this strikes me as odd, since it is my favorite test. For the uninitiated, this test is a continuation of your test pit, which is extended across the slope 2 meters, it is then cut back about 1.5 meters on either side and then the back is cut down to the same depth of the slope.
If a layer goes at this point it is considered a load of 1.
Next a skier gingerly stands on the top of the block, if it fails at this point it is a load of 2.
Then the skier makes some knee bends (partly weighting and unweighting the skis. If it fails here it is a 3.
The skier then jumps once, if it fails here it is a 4.
The skier then jumps again, failure at this point is a 5.
The skier is then replaced by a pedestrian jumping or stepping down to mid-block on skis and jumping some more, a failure here is a 6.
No failure at all is a 7.

I remember the rating scale as “Jump 4 joy” since a jump is a 4, and you are starting to get psyched once you get to a 4, a good little memory tool.

The summary in the OGRS is that a 1, 2 or 3 is unstable.
A score of 4 or 5, a slope is pretty suspect.
A score of 6 or 7, the risk of a skier trigger avalanche is considered to be low on that slope and possibly other, similar slopes.

This is a great test since it approximates the actions of a skier better than any other stability test other than a ski cut and it is fun and a good way to warm up after recording data in a hole in the snow. It is far from perfect and like all the other pit tests, can only be assumed to be 100% accurate for the immediate area of the pit, since we all ski slopes larger than 1.5 meters we need to evaluate the results of this test carefully and be sure that we do not over generalize.

Back to the reason for my omission of this test, a slope of at least 25 degrees is needed and 30 is greatly preferred. Another wacky rule of thumb is to subtract 1 for each 10 degrees of increased slope. For example a score of 4 from a test site at 32 degrees would translate to a 2 on a 52 degree slope nearby, which is a good rule if you can dig a safe pit on a 25 degree slope and can’t safely dig a pit on the 45 degree slope nearby which you want to ski if the results of your snow analysis are favorable.

Bullion Basin, Crystal Mountain 061202

I was very curious to get a look at the structure of the snowpack, since it has been an interesting week for Washington State weather, with heaps of snow and very cold weather. Since I was traveling alone, I was very cautious about which slopes I was willing to travel on, let alone to ski.
I chose to dig a pit in a less than ideal spot at 5370ft. It was closer to the trees than I would have liked but I did not want to stop in an avalanche chute and was hyper aware of the sun hitting the steeper slopes above me. The pit itself was a great learning experience for me and I made some errors.
It was the first Rutschblock test and the first Shovel Shear test of the season, both of which were done incorrectly. I will update that a little later in the week about how they were done and how they will be done in the future.
I found some nice hoar frost, which melted later in the day. Also, I found fairly cohesive snow bridging the weakness of the rain crust at 27 cm. In the upper layers there were a couple of failures with a RB4 at 112cm and 126cm, neither of which concerned me much and were stiffening up as the day went on.
I dug a hasty pit at 6400 ft with an E expose. It showed even stiffer snowpack at about 120 and less of a crust with greater cohesion. The sun was also further consolidating the surface snow. I skied this exposure all day without incident.
Perhaps most interestingly, at least 25 people passed within 5 meters of me doing my full observations, only three two stopped to ask me what I had found. This is a bit distressing. Thanks to Troy for helping my on my Rutschblock.