as i expected, the north aspect skiing, into canyon creek, was just fine yesterday. a really solid base with about 10" to make some easy, fun powder turns. and surprisingly, even the easy to reach and ski lines in the creek were largely untracked.
but to my surprise, was how well the front of the mountain skied. it was not frozen crust everywhere. although i did not explore widely, it seemed like the mountain skied well throughout, especially the top 2/3. it sure is crusty in town, but maybe we are going to be lucky on this one.
still, we need more snow. this is really apparent when i went for a skate ski out at Stillwater. some ice and bare spots are already showing up with the warm temps and light rains. let's hope el nino is not so strong to put us too deep into a drought right now. just a few storms and a slight drop in temps will do the job.
i haven't heard anything from others out touring, but am sure they are doing so. is this because no one wants to share what they are doing? or just because everything has stabilized so nicely that everything is a go? i hope it is the latter.
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Chris, I can't keep up with all your blog entries... You are having WAY too much fun! How 'bout sending out an email each time you update your Blog?
ReplyDeleteHeard about an avalanche on Big Slide on 1/14/10... Does anybody know if this was skier triggered? Would be good to know and share.
In reference to snowpack stability increasing, just wanted to point out that although this mundane weather and mild winter temperatures are promoting snowpack settlement, these weather conditions are also promoting "creep" in the snowpack under the effects of gravity and allowing the snowpack to "creep" downhill while increasing stress between the interface of the surface snow slab and the prominent uppermost dangerous weak layer… This is especially true on steep convex rolls and steeper unconfined terrain...
This was really evident in a quick test pit I dug on Chicken Bones last (1/15/10... SE exposure, 35 degree slope, 6' snowpack)...
The surface slab, average 1F hardness with a couple of new crusts in it, was resting on the still VERY prominent Christmas crust/surface hoar layer- about 4' down from the snowpack surface...
An ECT test on this snowpack/layer (I only had time for one) produced full column propagation on the 28 hit- ECT 28/28... Q1- So, it was hard to cause failure, but once failure was initiated, there was an evident energy release component. It is important to note, historically I have not been a big ECT fan, but recent results using the ECT have my undivided attention.
Well, anyway, good thing that damn layer is buried 4' down!
Right. BUT, this is where it gets tricky, BECAUSE as the snowpack gets a little deeper storm by storm, the obvious (dangerous) weak layers in the snowpack are getting buried deeper and deeper (in most locations). YOU ARE NOT going to see or hear clues related to this PRESISTANT weak layer as often as in the past... Why? 'cuz it's gett'n buried sooo deep- in MOST locations... Hence, SPATIAL VARIABILITY.
That's good!???
YES but NO, a thick slab will potentially insulate you from triggering an avalanche but also falsely increase confidence in snowpack stability- potentially taking you into steeper, more exposed terrain...
Just remember, terrain features can easily affect slab thickness... So, a weak layer that may be buried and under tension beneath a slab at 4'depth in a uniform unconfined slope, may only be at 2' depth on a convex roll or near a rock feature... Eazypeezy to trigger- even for cbm...
Once triggered, at least from my single ECT test, it appears the potential for propagation is high. So, as you decide to ski steeper and more exposed terrain, know your snow and be very selective of your lines.
Oh, also worth mentioning, the Thanksgiving ice lens is still way prominent (at least at this location) and the facets beneath this ice are imprssive 2-3mm/ F hardness... No time for stability tests.
Ted Steiner.
Chris:
ReplyDeleteOne more important point to mention that I forgot to... Steep terrain features in starting zones such as convex rolls, etc. are also the areas where the most tension will be stored in the interface between the slab and buried weak layer through "creep." It is another reason these areas are so prone for avalanche triggering and also a primary reason these areas are good to avoid- most all the time- but especially right now as our confidence in snowpack stability increases.
Gotta run.
Ted.