March 7, 2012
Observations from our Full Profile Study Plot at Fraser. Height of snow was 185cms in our study pit. 40 cms of low density storm snow has fallen in the last couple days. This overlies a strong rounding midpack of rounds and facets below, 1F-P in resistance. The Feb 21 interface is down approx 75cms and was not producing results to stability tests. We did however get several instabilities to 'pop' (SP) within the recent storm snow.
ITS GETTING DEEP AT FRASER!
February 8th, 2012
Wx observations from Fraser this morning at 0730. Overcast Skies, -8 degrees, with calm winds. 17cms of snow fell overnight, and our storm total from the past week is at 55cms (with settlement).
Went into Powder Valley and Paddy Peak are today to get a better idea of distribution of the Feb 21 Surface hoar interface and the additional load (slab) over top with this weeks storm snow.
In the Paddy Peak area, we dug on a South Aspect, at Treeline. The snowpack height was 135cms. 15cms of low density storm snow overlies a midpack and lowerpack of facets. Of note was a resistance change, down 45cms in the facets from 1F to 4F. This interface produced Hard "pop" results to compression test. However, we feel that there really was not a sufficient slab for wide propagation above this interface.
We dug two pits on North Aspects, one at Treeline and one in the Alpine. Both pits revelead two layers of Surface Hoar, down approx 45 and 65cms. These layers had a 1F+ slab above them. Stability tests produced consistent results in the Treeline and Alpine profiles, moderate "pops" on both layers. In addition, Extended Column Tests showed propagation was likely for both layers, in both locations.
In the alpine profile, we performed a Rutschblock test that showed skier trigability and propogation is likely, with the potential for step down. (triggering the first layer and the weight of that avalanche subsequently triggering the 2nd layer, buried deeper)
We are seeing incremental loading on these layers in the transitional snowpack. What this means is that we are not recieving enough snow to currently see a natural avalanche cycle on this layer, it has the opportunity to heal with each small load, but hovering around that 'tipping point'. The travel strategy for this problem, remains to be discipline. Avoiding large, steep North and East aspects where this layer would be a problem.
Winds picked up a bit from the South this afternoon, but by and large the area has seen very little wind with the new snow. The tree skiing was really good today!
March 09th, 2012
We spent the day in White Pass today where about 100cms of snow has fallen over the last week with out much wind. This storm snow has settled to about 60cms in our treelike snow study site. With the exception of the Feb 21 layer of facets on sun crust found on steep south aspects the mid pack in White Pass is rounded and supportive. Temperatures warmed up last night and the winds picked up form the SW picked morning (up to 70kmh at ridge line) as a result our primary concerns for travel today were the developing storm and wind slabs instabilities.
We encounters numerous signs of instability through out our day. Shooting crack and difficult trail breaking in the morning indicated the the storm snow was settling into a widespread soft storm slab. Strong winds at highway level and intense amounts of wind transported snow indicated that windslabs were forming in lee features. By mid day we were seeing a widespread natural avalanche cycle. Natural slab avalanche up to size 2 were releasing from ridge top loaded N aspects and mid slope cross loaded SE aspects. These were running mid way down their historical run outs (up to 400m in length). Ski cutting small wind loaded slopes at tree line produced avalanches up to size 1.5 even on low angle supported terrain. (See bellow)
Given these obvious signs of instability we opted to stay out of the Alpine for the day. We also were mindful to avoid ridge loaded and cross loaded features, and to took extra caution by avoiding or spacing out appropriatley when traveling under overhead avalanche slopes, and around steep unsupported slopes.
The winds are forecast to remain strong through the night with more snow arriving tomorrow. This weekend is a time to travel conservatively in avalanche terrain. For more information see the latest conditions report.
Also of note with there was widespread overflow on the lakes around Fraser. - Eirik
Tuesday March 13, 2012
Spent the day gathering baseline snowpack data from both ends of the forecast region, WhIte Pass and the Wheaton Valley.
Weather was nice, Mostly clear skies with some valley cloud hovering between 1100-1400m. Winds Calm and -9 degrees. Just a dusting of snow recorded over night.
In the White Pass, at our 900m Fraser Wx Study Plot, the snowpack depth is approx 200cms of snow. 30cms of settling storm snow overlies a layer of preserved stellars down approx 40cms with a 1 Finger (resistance) storm slab above. The mid pack is strong, composed of rounds and rounding facets down to 150cms where the broken down Dec 5 Crust exists. Below is facets (Pencil in resistance) to ground.
Stability Tests produced repeated 'pop' (Sudden Planar) results on this layer down 40cms. Yesterday, traveling in the Fraser ridge area, this same layer was observed with more of a wind slab developed above. We also noted signs of instability (shooting cracks from our skis) on small convex rolls where a thin wind slab exited-failing on this layer, however not steep enough to slide. The fat looking pillows below fraser ridge at Treeline and above appeared to be harbouring some lingering wind slabs from last weekends storm. Also, areas that had avalanched on Friday or Saturday, looked to be re-loaded.
Reports from Hwy Personnel that the North Easterly winds picked up last night, gusting 70km/h. This became more obvious on the drive back to town, areas that were scoured last friday (South Aspects) in the Tutshi Lake area were no longer scoured, and some S-Aspects looking 'fat' in places.
Please see the "Wheaton Valley" thread for snowpack data for the Wheaton.
March 14, 2012
We've previously been talking about the Feb 21 surface hoar layer in the Powder Valley region. Up until this point we haven't found it to be widespread in White Pass. Bellow is good evidence that this layer may be more widespread than we have thought up until this point:
This is photo of a recent natural size 3 avalanche in the Big Blue area to the east of Summit Creek. This was a large avalanche, the crown was roughly 500m wide, and 80 to 100cm deep. The entire slope avalanched and it ran for almost 800m. This avalanche propagated on a well preserved surface hoar layer which we assume is the Feb 21 layer we've been seeing further to the North.
Like I said we haven't observed this layer to be widespread in the Whitepass to date so seeing this avalanche yesterday was a nasty suprise and we're going to spend the rest of our work week trying to track it down. The fact that this is the only avalanche we have seen on this layer to date raises some questions in my mind? Is this layer isolated to certain features or is it a widespread problem that is that might be just starting to wake up?
Deep persistent slab avalanche often occur in cycles so I am going to be avoiding those large north facing aspects for the next little while. Surface hoar layers often trigger avalanche remotely and this particular layer down 80cm seems primed for human triggering given the right week spot. Discipline is the key to dealing with this type of avalanche problem, don't let tracks lure you into a false sense of security. Digging a profile at the crown showed this layer was failing with a "drop" under a moderate loads however recent snowmobile high-marks into the start zone immediately adjacent to this slide showed no signs of instability (Luckily!)
Please see our recent Youtube Video for more info
March 15, 2012
We headed up the East side of Log Cabin today to investigate the natural avalanche that was reported from last weekends storm. On approach, we quickly realized the magnitude of this slide, it had looked large from the air yesterday, but much more humbling once on the ground. A healthy size 3.0 avalanche. The debris is actually composed of 3-4 different avalanches. 2 size 2.0 wind slabs that likely released somewhere around March 9-10 (during the last storm), the weight of these avalanches caused a step down affect, releasing a deeper slab (size 3.0) on a surface hoar layer (preserved and size 6.0), buried approx 80-90cms (Feb 21 SH) further down slope. The crown of this avalanche is located in the lower part of what would normally seem like the typical start zone for this typical terrain feature. A location that is shaded and likely more sheltered from the wind, allowing the formation and preservation of the surface hoar.
This was a destructive avalanche, approx 300m wide and running 700-800m long. In the track/runout zone, it buried the common skier up track for accessing the East side of Log Cabin, not to mention a lot of common ski terrain. (see photos below)
The presence of this avalanche and the size 3.0 avalanche in the Big Blue (East side of the pass) area tells us this layer (where it does exist) is waking up, and is likely at or near the 'tipping point'. Isolated avalanche activity on a persistant week layer that exists in isolated areas makes it difficult to predict where and when this type of avalanche will release. Therefore, the way to manage this hazard continues to be discipline. Eirik and I will be staying off any steep terrain (25 degrees or steeper) that is sheltered and shaded (N to E aspects). Rember this layer is deep, it could be possible to ski a slopes all day without anything happening, but if you do tickle the dragon, it is going to be a large and unforgiving avalanche, likely over exceeding your expectations.
In the path of the size 3.0 on the East aspect of Log Cabin.
Eirik approaching the crown of the size 3.0, the wind slab released above this photo, causing a step down onto the surface hoar layer, approx 80-90cms deep.
Check out todays video from our crown profile.
From your description and pics that's the exact place that I saw large surface hoar on February 19 - in what I think people call the "7-11" bowl. I didn't look that closely at the time but it seemed to form in the bottom of the bowl where there's a little more shelter..........I guess, hence the crown in such an unsuspecting spot, like you say.
Thanks so much for sharing all of your awesome work!! I can't tell you how much you guys are appreciated in helping us all get a better sense of what is going on out there!
Wondering if you could just confirm this location. Same for the one at Big Blue.
Kirstie 5736.log cabin mountain.pdf
Thank you for the support Michelle! These observations of the Surface Hoar on February 19 are very valuable. I would urge fellow backcountry skiers to share these types of observations on the forum, especially if you are seeing a persistent weak layer forming on the surface, such as surface hoar but of course not limited to that (others include, facets, sun crust/rain crusts with facets above, etc). Photos are very valuable, specifically backcountry groups that are seeing these 'persistent' in nature layers forming in specific/isolated terrain features. This will ultimately add to everyone having a better idea of distribution of these layers. I hope that did not come off too demanding, just trying to promote sharing of observations! Thank You!
March 20, 2012
Snow Profile observations taken from our full profile site at Fraser Wx Station, 900m elevation. 30cms of settled storm snow overlies a strong mid and lower pack of rounds and facets. Stability tests revealed an Easy "pop" down 20cms within the storm snow, otherwise no other instabilities were noted in the study plot.
Recent North winds appear to have their affect on the Fraser Chutes area. Reports of a breakable sun crust on Solar aspects, apparently not the best skiing! Otherwise a nice day in the mountains, broken skies and light to moderate North winds in the Valley bottom.
See "Wheaton Valley" thread for observations around Annie Lake.
March 21st, 2012
The White Pass welcomed spring with a beautiful if cold day. Justin and I spent the day exploring the east side of the Pass and continuing to track down our mid Febuary surface hoar.
A supportive upper pack made for easy travel and allowed us to see a lot of terrain.
Winds were light from the north throughout the day, redistributing what ever snow was left available for transport into a revers loaded pattern We saw 2 size 2 wind slab avalanches from earlier in the week on slopes that see an exceptional amount of loading from north winds. However, apart from a couple of point releases starting up in the rocks on steep sunny aspects we saw no signs of instability.
The Feb 21 SH remains a concern and we are still avoiding steep N aspects.
Check out our new Blog thread for Eirik's thoughs on the distribution of this old surface hoar problem we keep talking about!
March 22, 2012
The high pressure continues in White Pass providing easy travel at Alpine and Treeline Elevations. We were able to cover a lot of ground again today. Today we spent our time in the Fraser, Taiya Peak and Summit Creek area. Winds were light to moderate from the NE all day, making it quite chilly at times. Our travel concerns continue to be the Feb 21 SH layer, remaining awfully suspect of any large North facing, shaded and sheltered aspects. Our secondary travel concern was winds slabs on South aspects from the reverse loading this week. Yesterday, we observed a few size 2 Natural Wind slabs released on cross loaded slopes from the Northerly winds. Today we had a size 1.0 Sled Accidental on a small, steep south slope on Summit knoll (see photo below). Shallow in depth, 10-20cms.
March 28, 2012
Full profile from Fraser today showed a well settled snowpack. Midpack and lower pack are strong and stability tests produced no results. Height of snow in the study plot is 170cms. Of note was small but present surface hoar on the surface by mid day, however sun was having a strong influence, top 5-10cms was becoming moist.
Observed Numerous wet loose snow and small size 1 slab avalanches on steep solar aspects along the highway corridor by mid-afternoon. Lots of movement all along the corridor from White Pass to Carcross. That sun is packing some heat!