YAA CAC Techs - White Pass West Conditions Report

Hi Klondike skiers and sledders, We're the new YAA CAC avalanche techs. We're excited to be up here and working on the development of a new forecast region for the CAC's Public Avalanche Warning Service. One of the program's goals is to have a Public Avalanche Forecast up and running some time early January. In addition, stay tuned to this thread for routine reports from the field throughout the winter. DISCLAIMER: This WILL NOT be a forum for posting any sort of avalanche hazard forecast. It WILL be a forum for publicizing observations from where we have BEEN working, on what the conditions we encountered WERE, and what our concerns for travel WERE at that place and at that time. If you see us working out there please stop by and say Hi. We look forward to meeting you all out in the mountains, Eirik and Justin

111206 Conditions Report. Today we went for a reconnaissance flight to get acquainted with our new forecast regions. All I can say is "WOW!" I can't wait to get out there and start exploring. Our only notable observation from the White Pass area was a size 2 slab avalanche on the northwest aspect of Log Cabin. It appeared to have released naturally in a wind loaded feature mid slope sometime during or slightly after the storm on Monday. Apart from that most of the snow from the storm seems to have been blown around (or away) by the strong winds that came with it. Windward features were scoured and windward features appeared loaded. I know that's not a lot go off but I'm not confident in saying any more right now given how much terrain we saw and how far above the terrain we were. - Eirik

111210 Conditions Report: We spent the day today running a CPD day for members of the Yukon Avalanche Association up in the Summit Creek Area. We had a great day, met some great people and explored a new area (to us at least). On our drive up to Summit Creek from Fraser we observed numerous small (sz 0.5-1.5) wind slab avalanches mainly contained to the steeper NW facing lee features at or slightly above tree line. These were new since Tuesday and although I can't say when they ran they were our primary concern as we started poking around the summit creek area. We stayed fairly close to the highway as our training objective for day was tracking down and checking out the wind-loaded pockets which we had seen were capable of producing avalanche and confirm some of our suspicions about structure of the snowpack. Snow quality for skiing at Summit was surprisingly good "dust on crust" considering the amount of wind the pass has seen over the weeks week. The snowpack depth ranges from 80cms down in the meadows to over 3m in some wind loaded features. As far as the snowpack structure we found between 10 and 40cm of new snow sitting on a 10cm thick laminated multiple crust-facet interface (which I'm calling the "111205 Crust"). This storm snow varied from low density loose snow to isolated pockets of stiffer wind-slab.The mid-pack is fairly well consolidated but broken by another crust which was down about half 60-80 in all but the most wind-loaded spots (I going to call this one the "Mid-Nov. Crust" unless anybody has a more accurate date for it). At the bottom, all this is sitting on about 5cm of basal facets, although surprisingly we didn't observe any depth hore. Traveling through terrain our groups produced a number of good whumphs typically in and around the more wind loaded features. This collaborated our earlier avalanche observations and suspicions of instability in these areas. Snowpit tests snowed that this failure was happening on the interface between the storm snow and the 111205 Crust and that when the overlying storm snow was sufficiently "slabby" it had the stiffness necessary to propagate this failure. Remember that "Failure + Propagation = Avalanches". Right now in the Summit Creek area the only slab we could find was limited to wind-loaded features but I'll be interested to see if that changes in the next couple of days. Thanks to everybody who came out today. I hope you all had as much fun and I did. - Eirik

Today we went out with the goal of getting a sense of the variability in weather and snowpack from one side of the pass to the other. We started at Log Cabin, then check out the Fraser Chutes before poking around the Summit Creek. Obviously we didn't get to go to deep in any of the areas but we got a good overview of what the recent storms had up there. In all areas we found about 110cm of snow in sheltered areas although it ranged between 40cm and over 3m wherever the wind had had a chance to push it around. I'm guessing the pass got about 45cms over the week but it came with strong winds and relatively warm temperatures. The storm snow had had settled into a 20cm deep soft slab at Summit and although we didn't see any I would expect pockets of deeper, stiffer wind slab to have formed in all the usual lee features. Log cabin hadn't seen as much settlement in the storm snow although we did find isolated pockets of soft slab on N to NE aspects that reacted to moderate loads with clean shears. These were releasing on an interface within the storm snow down about 15-20cms. We also got some smaller features to avalanche (size 0.5 to 1) by jumping around on the convexitities unsupported slopes. Given what we saw we were definitely treating the larger wind-loaded features with extra caution, altering our route whenever we started to feel the snow stiffen under our skis, and trying to minimize our exposure to any terrain traps. Deeper in the snow pack the 111205 crust facet combo is still widespread down about 60-80cm in sheltered areas and the mid November crust can be found down 80-100cms. Even though its getting buried deeper they are both is still a concern to me. The 111205 Crust failed under hard load in our compression test, but that didn't give me any confidence that we'll be putting it to bed any time soon. I think that with a more consolidated snowpack on top of it is going to be harder to trigger but will also be capable of producing larger avalanches; a classic persistent week layer scenario. On a positive note thought the ski quality in unwind-effected areas at Log Cabin was excellent today, the 20cm of fairly low density powder made the few turns we got in thoroughly enjoyable. - Eirik

111229 Conditions report. Hello All, we went up log cabin yesterday to check on conditions. Sorry for the late post, we have been having trouble lately posting on the discussion forum. Skies were broken, temperature steady around -10 at treeline, winds were moderate from the SW with some snow transport, loading the NE aspects. This wind slab (20-40cms thick) was reactive to ski on unsupported, small convex rolls at treeline in lee. Snowpack observations were taken on a N aspect, at treeline(1155m), height of snow was 260cm. Last weeks snow is settling into a storm/windslab approx 30-40cms deep (same layer reactive to ski) and producing Easy Sudden Planar (Clean and fast) results. Mid-snow pack is generally well settled with the exception of a old wind slab down 60cms still producing hard clean planar results. The Dec 5 crust/facet combo was down 140cms in this location, producing Broken results and feeling 'stubborn'. This layer can be found much shallower in adjacent slopes and appears to be widespread up to 1350m. We observed one Natural avalanche on steep NE facing terrain in the alpine, visibility was obscured but suspect the recent wind slab layer. The alpine snow was highly wind variable and ski quality in the alpine was "ok" and enjoyable at treeline and below. A good day in the mountains. Cheers, Justin *Please excuse if any other reports for this date get published, I have tried posting with a few different methods."

120102 Conditions Report from Tushi Chutes Area. Went for a short trip into Tushi Chutes today. 5-10cms of low density storm snow in the area. Ski quality was quite good in the trees with still a little tricky route finding through the alders but more than manageable. Temperature was -2 degrees and winds were light from the south below treeline and moderate at treeline. Drove up to Summit earlier in the day to find moderate to strong winds from the South-west, Intense snow transport and limited to nil visibility. Cheers, Justin

We traveled up Summit drainage today. Winds were moderate from the North in the Alpine with light snow transport. Light snow started in the afternoon and temperatures were steady at -11. We observed Natural wind slab avalanches to size 2 on Steep convex rolls, North-East Aspects. These are soft slabs at treeline, down 20-40cms. Suspect 24-48hrs old. These wind slabs continue to be our primary travel concern. Ski quality was wind affected in alpine and treeline. Justin

We headed into Powder Valley today. We found it had been sheltered form the N winds associated with the outflow we experienced after the last storm. Fraser show about 10cms over night which matched what we saw on the road, As a result we were plesantly supprised to find 20-30 cm of of low density snow ontop of of a supportive old wind skin For two boys from BC it made for the first good powder skiing we've had since we got here. Unfortunatley I expect that with the forcasted warmer temperatures this will settle into a soft slab over the next day or two. On average at treeline the snow pack is about 110cms deep. The 111205 crust that was our primary concern before christmas is still out there, down about 80 cm, but it apears to be breaking down and we could only find it in isolated areas. The midpack is faceted and week and feels hollow bellow the wind skin as one would expect in the transitional snow pack on found in Powder Valley. The lower snow pack is characterized by deapth whore. If your lucky and can get out there tomorrow you might still find some really good skiing. Eirik

111210 Conditions report     We dug our weekly full profile today. I think it is interesting info worth sharing but by its nature its going to be a little technical and probably won't be of equal use to everybody reading this.     Site: Fraser - flat, sheltered weather plot.     HS: 136     Pack summary:   70cm of low density snow has fallen since the 1st and has settled into a 40cm thick soft slab. This lies on fairly well consolidated although slightly faceted mid pack. The 111204 crust facet sandwich is still around down 90cms and dosn't show any signs of breaking down yet. Its not a layer that is really playing much of a factor in my decision making any more but I'm keeping an eye on it in case it wakes up again in the spring.     Test Results:   CTE 8 SP down 15cm x 2   CTM 12 RP down 27cm   CTM 15 SP down 35cm x2   CTM 18 RP, CTH 22 RP down 40cm   CTH 27, 30, SP down 57cm   DTT H23 SP down 88cm (storm instability)   Eirik

120111 Conditions Report: We thought we would go and poke around Log Cabin as a low risk travel option given the series of fronts that where forecast to materialize today. Luckily for us they didn't come with the intensity we were expecting and we enjoyed the occasional reprieve from white out conditions and blowing snow. Winds were strong at the Pass overnight and had done a great job at moving all new the snow around. In the alpine some really stiff hard slabs have developed in wind loaded features and although these felt quite supportive we decided against push it onto any of the larger unsupported features. At treeline various storm instabilities exist withing a 45cm deep soft slab. We jumped around on a couple of smaller features and only got shallow results in the upper storm snow although we both felt that given the right piece of terrain we would be suspect of the whole upper pack. Eirik

Went to check out our transitional snow pack at Tushi Chutes today. We found an HS of 120 and a much more faceted snow pack than we had found previously at the pass summit. We dug a test profile at TL on a SW aspect where we found the same instabilities in upper pack we've been seeing all week. The mid pack was comprised of 20 cm of stiffer rounded crystals on top of 20 cm of facets overlying the 111205 crust. This was shallower than we've seen it in other places lately (down 80cms),l reactive to heavy loads and still exhibited propagation propensity. That said the stiffer layer in mid pack was supportive to skier weight and we felt it was doing a good good job of anchoring the snow in the steeper broken treeline terrain we opted to ski. - Eirik

Eirik, Justin & I (ilya from Revy) travelled in the "Fraser Lake" basin today investigating how last week's cold temperatures changed the snowpack as a whole, and checking out the reverse loading pattern from last week's northerly winds. First the snowpack... the upper layers are dust on crust (10 to 20 cm of dust and 10 to 20 cm of crust) above a layer of softer facets (sugary snow, 4 finger hardness, about 10 cm thick). The mid-pack has faceting but still quite hard (1 finger or pencil hardness). The early December rain crust is 65 to 100 cm deep and below that are pencil hard facets and depth hoar. The December rain crust didn't perform with stability tests in our study plot, however, in the field it did react in one profile (compression test hard, pop). Last weeks winds created a widespread "wind crust" that's hard & supportive everywhere we travelled today. Today's concern was the hard slab; likely hard to trigger but hard slabs tend to release above you (when you're lower on the slope) and are unpredictable. Thinking about what comes next, we're going to be watching the dust on crust. Right now the top 20 cm is blower snow; however there's no real bond with the hard wind slab below. Conditions will be verry different if the top 20cm settles into a slab but the bond below doesn't change. Watch for warming, more snow or wind drifting - any of these could quickly create a storm slab hazard. We rated the hazard today as Moderate at Treeline in the area we travelled. Check out todays videos on our new YouTube Channel: YAACACTech

120125 - Powder/Sunshine Valley. Today Justin, Ilya and I headed into the Powder Valley area to see if how the cold winds had affected our transitional snow pack We were lucky to meet a couple of local sledders at the trail head who punched a great trail for us almost all the way to Mt. Racine at the head of the valley. The wind had certainly done its work on the ski slopes above the access road since we were last there scouring the ribs to ground and cross loading the gulleys. We headed right at the fork of the valleys and took advantage of the broken clouds to get up into the alpine. In our transitional snow pack we found similar dust on crust layering to what we found at White Pass yesterday. The overlying storm snow is starting to settle into a soft slab, although not as fast as we had expected. This is likely because temperatures did not rise as much as foretasted. Bellow the storm snow we found the widespread wind crust everywhere we went although it got more progressively more supportive the higher we got. The storm snow is still reactive and showing no signs of bonding to the underlying crust (compression test easy, pop). The crust felt and sounded hollow and failed on the underlying facets (compression test moderate, drop). Lower, the mid pack was faceted but firm and we found the December rain crust as high up as 1500m. Our primary concern for the day for the day was the soft slab instability and we managed our hazard by avoiding steeper terrain. We were a little surprised not to see any natural activity in this layer but I think this was a result of the cooler temperatures inhibiting the snow settling into a slab. That said the winds picked up and swung around to the south early today and I expect to see reactive pockets of wind slab developing in lee features in the next couple of days. We rated the hazard as considerable in the alpine, moderate at tree line, and low bellow tree line today in the area we traveled. Check out the today's test results on our youtube channel: YAACACTech. - Eirik

120126 Conditions Report

Spent a half day on log cabin, weather conditions were great, broken skies, approx. -11C and winds were light from the South.  10-20cms of soft slab overlies a hard wind slab.  This wind slab was not as prominent at treeline in Log Cabin as we have seen it further up White Pass but was supportive and stiff in the Alpine.   

We observed easy hand shears in the soft slab at treeline, down 20 and 40cms.  Additional stability tests produced easy results (CTE) in the soft slab and Moderate (CTM) in the facets below our wind slab, both layers “Popped”.  Ski Cuts on lee features in alpine produced no results, other than good skiing!(see attached photo)

Our primary travel concern continues to be the soft slab over top of our hard wind slab.  Things to watch out for are an additional load of snow, rising temperatures and wind over tomorrow and into the weekend.  One or a combination of these could turn the powder into a more cohesive slab.  

Our secondary concern is the layers of facets bellow the widespread hard wind slab.  This wind slab will be an issue on steep unsupported terrain.  Hard slabs are commonly triggered from below or in shallow areas where it is less bridged or less developed.

Clues to look out for in the field?  Shooting cracks at the ski tips, hollowness feeling under the slab.  When breaking trail, is the sides of the trail collapsing behind your skis or is it sharp, clean walls?  Clean walls indicate a harder slab development.

Collectively we called today’s hazard at Log cabin; Alpine-Moderate, Treeline-Moderate and Below Treeline-Low.  However, keep a careful watch on the weather moving into the weekend and expect the hazard to rise if we receive significant winds, new snow and warming.

Happy Skiing!  Its good out there!

Justin, Eirik and Ilya

Eirik enjoy some nice alpine turns on the cabin.

 

Ilya shredding down log cabin on thursday.

February 2nd, 2012

Eirik and I travelled into the Mt. Montana area today, just South of Carcross.  We travelled up into the alpine where we experienced strong southerly winds (steady 50km/h, gusting 90km/h) that were sublimating any remaining snow left for transport.  -5 C was recorded at 1500m and a balmy +1C at Carcross townsite.  No precip and skies were broken at times throughout the day.

The snow distribution in this area could be described as barren, wind-scoured and highly-variable.  Where snow exists, a shallow facetted snowpack dominates, with a 10cm hard supportive windslab overlies a rotten mid-pack of facets, broken by more facets and depth hoar on the basal layer.  The height of snow in the alpine ranges 80-100cms.

At Treeline, 10cms of soft slab overlies a harder wind slab but not supportive to human weight in more sheltered areas.  Again, facets dominate below these layers to ground.  The soft slab produced moderate hand shears and was reactive to the weight of a sled. (really????)

Cheers,

Justin

Anyone know if Wiarton Willy saw his shadow today in Whitehorse?