Thursday, January 7, 2010

clear and cold

is this classic montana or what?  we go from mid 20's deep powder, get hit with some late afternoon rime, then the wind comes ripping in, bringing in a high pressure, super cold front.  in less than 24 hours we have gone from deep pow skiing, to wind blown, soft snow, where wearing all your clothes is necessary. 
fortunately, the wind did not totally rip up the skiing. in fact, it stayed quite nice. 
i spent the day off the resort, in the canyon area, skiing mostly low angle trees, but occasionally venturing onto steeper slopes.  we did not dig a pit, as the cold temps kept us desirous of constant movement.  we had nothing but great skiing conditions, and felt very safe throughout the day.  the biggest impediment to nearly perfect skiing was snow debris off trees that had hardened up like avy debris.  it was easy to recognize, but once buried, might trip up many a skier like a snow snake. 
we could feel the tiny rime layer right at the top of the snowpack from the end of the day on tuesday.  and already surface hoar is forming on top of this crust.  so, yet another layer to be wary of in the future.  i kind of get the feeling that backcountry conditions will be relatively stable, but with hidden pockets of instability.  although this is often the case, with our many buried and super dangerous ice layers, the possibility of small slabs stepping down to these layers is of high concern.  often these hidden pockets are impossible to know.  but it helps to stay away from convex or concave slopes, rollovers onto steep terrain, or anything that seemed to be wind loaded. 
which brings up the concept of "spacial variability".  what does this mean and how important is it? 
i have long had trouble grasping exactly what this means.  but on my trip to sun valley area over new years, we did a short tour near the summit of galena pass.  they have an absolutely horrible and shallow snowpack, even for there.  but we dug two pits, less than 500 yards apart, one approximately 300 feet lower in elevation, both on the same aspect, and similiar slope angles.  why did we dig two pits so similiar.  well, mostly they were easy to dig, due to the shallow snowpack, and we were with a snow nerd , ex of these parts.  the first failed on an "extended column test" on the 16th hit, the 6th from the elbow, Q2.  no propogation.  so a poor quality failure, under moderate, nearing a high pressure hit, that did not move thru the snowpack.  RELATIVELY SAFE.  in the second pit, we had a clean failure Q1, at ECT 13, that completely propogated across the snowpack.  RELATIVELY DANGEROUS!  this is a great example of "spacial variability.  two spots, about the same, but in just slightly different places. one seems safe, the other not. 

how important is it?  read ted's comments from the last blog, and look at the youtube video of the fatality in cook city.  snowmobiliers all over, but he hit the sweet spot.  

okay, enough.  with all that said, we ended our day, somehow on top of a highly visable, beautiful line facing the valley and the base of the ski area.  staying away from a rollover, a convexity and the steeper skiers left line, we minimized our rish, and skied into the open terrain and had perfect turns.  should we have skied this slope? maybe not, but it did not move, and the turns were the best of the day. 


  1. Hey Chris,
    You're right, what a day. Glad you got out. I thought I'd share my observations from the Middle Fork yesterday. Guess what, NO wind effect, nada. Big surprise to see the trees still cloaked with pow. Four of us toured up from Essex to Marion Lake in 16 below temps. The brush is finally disappearing and the trail had 10 to 20cm of fresh for pleasant skinning and descending. Had a few settlements in the lower lake basin that we attributed to buried elkweed collapsing.

    Only a few crown lines visible on big east facing cirques and some surface sluffing from point releases. We dug 2 pits at 6500 ft on south facing slopes above the lake, one 32 degree and the other 36. Similar results in both. Here's what we found on the shallower angle slope.

    For starters the top 10 to 15cm of soft snow is super reactive (CT3 Q1) and just beginning to slab up on a very subtle facet layer. Seems to me that this will quickly heal up. Lots of sluff potential for now. The real concern on south slopes is the 5-10 mm facet layer sitting on the XMAS melt freeze crust down 50 cm with a 2 finger slab above. Column results were CT12, Q1 and extended column results ECT 23, Q2. The slab did not want to propogate, which was surprising given the unhealed nature of the facets. Facets were laying flat, however, having already collapsed where we investigated. Total pack was about 140 cm.

    I would agree with the GCAC advisory for now, although like I said, no wind effect evident. Our confidence in the snowpack increased as we toured out to the unnamed high point on the north side of the lake. Somebody had skied several lines solo the day before and apparently survived. We then cut a couple of cornices above the prominent south facing couloir off the high point and produced nothing more than a pretty good sluff (top 10 cm) which did not step down and ran maybe 1/3 path. Temps were probably 10 above on the ridge.

    We skied the left side of the couloir in and out of the trees in some pretty awesome snow. Hard turns would sink you down into the denser underlying snow and light turns kept you in the champagne. Yesterdays full sun formed the slightest zipper crust near the top but most was pow.

    Finished the day touring up to the south ridge above the lake and skiing one of the 45 degree north facing chutes. Hasty pits on the way up showed once again reactive 10-15 cm surface snow but no melt freeze, just smaller facets down 50 cm or so. It's my opinion that the steep lines above the lake are pretty self controlling, subject to constant sluffing and natural bombing from the cliff flanks. We had some substantial fast ski sluffing to the lake. The top bit would pretty much go right away and was hard to stay in front of. Below that was soft styrofoam snow that was fun to ski.

    I think the winter is shaping up to be alright but choose terrain wisely and keep digging pits. By the way, I totally agree that we all had better behave when skinning up Big Mtn. It would definitely suck to be banned. If forced to choose routes, I'd choose Toni Matt and Russ's Street.

    Cheers, Pete

  2. hey chris,
    just wanted to throw this out. a couple friends and i were skiing off spruce nob(canyon creek area) last sunday, when one of our group triggered a slide. it was pretty big, two foot crown and probably 50 feet wide. this was on a slope that was probably 30 to 35 degrees and very treed. he was tumbled and lost his poles and hat and goggles. he managed to grab onto a tree and the slide ran past him. it was slow moving and did not travel all the way to the bottom but big enough to do some damage. we were not shocked but definitely surprised. it was an area that we had skied many times before and considered it relatively safe(familiarity?) just wanted to get the info out. so be careful out there!

  3. I have been touring through out the Middle Fork, Upper Mcdonald Valley, and Marias Pass Area over the last four days. The Middle Fork has had a significant wind event over night on Tuesday Jan 5,2010. This event has been followed by snow with light winds. I have noticed that the wind deposited snow appears to be muffling the effects of the previous weakness obviously some bridging. Most areas have 12 to 20 inches of fresh snow on top of the previous wind event. This bridging with the colder temperatures adding to the stiffness of the snow pack is making for some great skiing. The problem is that weakness is still there. We found signifacant whoomphing and settling both in the valley bottoms and along the ridgelines. This is adding to the stored energy in the snow pack and shear quality has increased in our recent pits. We have also found that the ridges are wind loaded from both directions with cross loading becoming less obvious. Prior to this wind event we had very drastic settling and shooting cracks that were running 75 to 100 ft in the wind loaded areas. The snow pack is strong untill it is not and warming temps will play a big role in the tenderness of the pack. Use good judgment as it is easy to get over confident. I am still seeing issues with lower elevation snow pack, especially in areas with rock out croppings, and trees. Caution is recommended. Enjoy. ~ Greg Fortin 892-2173