Friday, January 31, 2014

Pilot Peak - The Last day of January 2014

Skiing was fun at Mores Creek Summit with 10-15 cm of new snow in top of a supportable rain crust.
Rain runlets at 6500 feet
The game today was to do big turns, ride fast, and do BIG turns to stay above the crust!
Big turns from my Sir Francis Bacon!
Last night's clear skies, cold temps, light winds, and water moisture left by the departing storm produced ideal conditions for the deposition of surface hoar. Also the somewhat warmer rain soaked layer below cold snow metamorphosed the new 15 cms of snow into near surface facets. Today's conditions were not like skiing soft dust on crust. Skiing the combination of a thick surface hoar coating in top of creamy near surface facets was fulfilling, particularly compared to the variable mixed conditions from last weekend.
Top of the World
The truth is that today I was suppose to do research work at MCS, and generate temperature data sets that will allow me to estimate thermal diffusivity of the various snow layer. But temperatures today were too cold to be sitting in the snowpack for +1 hour. Temps were in the -7 Deg-C range for most of the day and light winds from the NW kept the air chilly. The only setback was that I carried of instrumentation in my pack that I never used.

The only reactive layers we identified today are the buried facets from early December, which is now buried at ~ 70 cms. This weak layer continues to fail propagation saw tests with sudden planar fracture character. Compression tests support a picture where the 70 cm weak layer is hard to trigger (CTHQ1), however in one occasion a column failed during isolation (CTVQ1), and while skinning up a whumpf was triggered. This suggest that there are still isolated locations in steep terrain where it is possible to trigger a high consequence avalanche!

Conventional wisdom is that hard layers (rain or wind crusts) can isolate a weak layer and make them hard to be triggered.  This can be  a dangerous misconception. Fracture initiation can and do happen at weak spots or trigger points. Currently, the trigger points in our regional snowpack are highly variable and hard to pinpoint due to the thin and variable snowpack as well as highly faceted basal layers. Proof of that was the whumpf that Evan and I triggered later in the day as we skinned up 'Almost Top of The World', where the burly rain crust failed to "bridge' the weak layer at the random trigger point we happen to found.

Winter recreationists will notice this weekend a set of snowmobile tracks at Top of The World bowl. The bowl main line was not skiing well. Winds had transported away the new snow, but that did not discourage snowmobilers from punching it. In fact one of the snowmobiles got stuck near the bottom or a while. I hope that this is not a trend, and that such practice will NOT persist. Two weeks ago Top of The World bowl became a snowmobile playground. I like snowmobiles, and have use them to access terrain. But it is important to avoid damaging the good relationships skiers and snowmobilers enjoy at MCS for the act of few folks that might not know that they are accessing terrain that ski tourers often use. I only hope that other snowmobilers will influence their community and explain their peers that snowmobile machines allow them to get into much farther terrain not easily accessible by skiers. Ski tourers appreciate the generosity of snowmobilers that leave untouched snow slopes within 5 miles of Mores Creek Summit and Idaho 21.
Boise Mountains in the horizon from Top of The World. Notice Almost top of the World slope, and farther back the Knob Ridge.
Winter Corner is in the shade behind the Knob ridge.

Sunday, January 26, 2014

MCS conditions for Jan 25th

Not much can be said ... we desperately need snow! Two weeks of no precipitation in an already thin snowpack as well as diurnal temperatures exceeding the zero degree temps have resulted in highly variable snow surface conditions.

Yesterday at Freeman peak we found dense and creamy facet skiing at shaded slopes, and the skiing was not too bad at all. But meters away a minefield of breakable crust was ready to remind you about the temperate temps in the mountains during the last 10 days.

I was surprised about the high level of optimism ... skiers and snowmobiles were out in force to enjoy Mores Creek Summit recreation area this past Saturday.

I do not track or compare multi year snow conditions too often ... but I cannot remember such a poor snowpack in the 22 years I have been skiing at Mores Creek Summit. The next snotel chart for Mores Creek Summit snotel is not encouraging. The chart suggest that MCS has an approximate deficit of 5 inches of SWE (snow water equivalent), or if we assume snow densities of 10 % (pow conditions) we are missing 50 inches of snow!

I do not recall a January where I could see so much dirt at the south aspect of Pilot Peak, or that I had to take my skis off to go over rocks when skinning up Freeman Peak along its East ridge.  Between the road and 6600 feet the snowpack at N and NE aspects have a depth of 80-90 cms. At 6800-7000 feet the snowpack supasess the 1 meter depth at N and E aspects. The next pictures illustrate the poor coverage conditions.
Lower Freeman Ridge looking into lower Pilot Peak.
Freeman Ridge - 6500 feet
Last weekend I skied at Baker Mountain- Washington for the first time. It has been in my list of places to explore for too long! The backcountry skiing opportunities are limitless! I was quite impressed and will be back late in March to further explore this area.

Before spending the MLK weekend at Washington, Pedro and I had a string of fabulous days skiing Idaho's mountains. We closed the week by having a phenomenal ski day on Thursday January 16th:

 Jan 16th MCS Blog Posting

Days have passed since January 16th, warm temps have affected the snow surface and no snow refresh to cover old tracks - but I did not want to face reality. I got myself busy with university work. But I knew I had to visit the backcountry to conduct a snow temperature conductivity experiment for Miguel,  a BSU Hydrology PhD student. So yesterday, I spent several hours playing with IR and high speed thermocouple temperature instruments.

I have to admit that I was happy to see stashes of soft snow during my climb,  but the thinly covered slopes got me very worried. It is the end of January, and it feels more like the end of March minus 1.5 meter of snow. Not good!

Check the next video clip. Clearly, the basal weak layer continue to be reactive to propagation.

No surprises here ... this propagation saw test was conducted at 6500 feet in a Northeast aspect slope with 28 degrees in steepness. The buried layer of facets at the 50-60 cm depth continues to have the potential to propagate fractures. The score for this test is codified as PST25/100(End)Q1-60 cm down. The same test score was reproduced when the test was repeated at the 50 cm interface. By the way, my ski touring partner initiated a whumpf earlier in the day.
Snowpack at 6500 feet, Northeast aspect
Compression tests results suggest that the 50-60 cm weak layers are not easy to trigger.  It should be noted that the structure of the current snowpack does not seem to favor ECT testing, where a combination of weak layer depth and thick slab favors the collapse of the isolated column where not all isolated columns result in fracture propagation. This issue with ECT testing is denoted as a false stable, since it can be mis-interpreted as results where no evidence of instability was found. For this season basal facet instability problem I have been often relying in the PST test methodology.
Snowpack at 6900 feet Northeast aspect
No weak layers were identified above the 50 cm depth. The above pictures shows interface at 22 and 30 cms. The 22 and 30 cms interfaces were unreactive to compression tests, and weak layers (facets) were not present at the elevations we studied the snowpack.

It is understandable how excruciating it is to deal with the existing instability problem. We have a regional snowpack, from Eastern Oregon to central Idaho with a highly variable buried weak structure. This weak structure continues to produce evidence of its capability to propagate fractures. The depth for this weak layer of facets varies from 50 up to 80 cms., suggesting that if an avalanche is triggered it will involve significant amounts of snow, where terrain traps can make rescue challenging due to burial depth. And it does not helps that the weather has been tranquil with mild temps resulting in ~10 cms of snowpack settling (settling is NOT whumpfing - settling is the process of where the snowpack densifies as air porosity is decreased in the snowpack) . The current conditions can easily be confused with periods where avalanches are not possible. And that is NOT the case!

We are dealing with a case of HIGH uncertainty. The weak layer distribution is highly variable, as well as the avalanche trigger likelihood. Slopes above 35 degrees should be treated with suspicion, particularly if the snow depth is variable making easier to find shallower spots that will make it easier to trigger an avalanche. Even careful evaluation of moderately sized slope cannot guarantee that a basal weak layer will not be triggered. There is just too much to variability in the snowpack structure!

For Mores Creek Summit (MCS), the snowpack seems to be fairly uniform in depth, reducing the probability of  shallow spots that will make it easier to trigger avalanches. But I observed yesterday some specific locations with signs of wind transported snow at ridgetops above the 7000 feet. Be mindful of wind effects at specific locations not only at MCS, but at any alpine or sub-alpine terrain in our region. Wind effects results in a double whammy situation where the slab is stiffened, and the distance between YOU and the weak layer can be reduced, making easier to trigger a slab with weak layers close to the ground!

Friday, January 17, 2014

Father and Son Perfect Day at Copper - January 16-2013

Perfect days do exist. I had such a day yesterday. The tranquility and solitude, as well as the beautiful terrain of Copper's sub-alpine forest with its 'just right' spaced trees. When such special place is shared by father and son ... there are no words to appropriately describe this magical moment, but the next video will!

If you watched the video, you might have notice the Propagation Saw Test (PST) stability test. The score was PST30/100(End) - 80 cm of depth at 8000 feet on a slope with 28 degrees with a north aspect. This is evidence of instability. The snowpack is capable of propagating a fracture over significant distances. The risk of avalanches with propagation potential relates to the much larger amount of snow involved in the avalanche. Check the next picture of what propagation means, and how an avalanche propagated readily through terrain at Banner Summit.
Avalanche at Bull trout Point
The score for the Extended Column Test at the same slope as the PST (8000 feet on a slope with 28 degrees and north aspect) was ECTN. The weak layer at 80 cm is deeper than the recommended maximum depth of 70 cms. This season Pedro and I have notice that the heavily faceted nature of the snowpack in our region combined with the depth of the advanced facets make ECT an unreliable tool for identifying fracture propagation. Last week ECT tests failed to consistently detect propagation potential even when many whumpfs and cracking have been present, while the PST have been very consistent.

The 30-35 cm interface seems to be sintering well, confirmed by lack of reactivity during yesterday's tour at Copper, and few days earlier at Pilot peak. We keep searching for buried surface hoar but have not detected this structure during the last tours.

I should comment that CT scores were CTMQ1(SC) at 80 cm. The sudden collapse (SC) fracture character did not revealed a well developed gliding surface. But the PST failure resulted in a very clean gliding surface along the fracture plane. I have to admit that I was quite surprised by it! The weak layer is close to 10 cms in thickness, and I could NOT distinguish a gliding surface from CT, ECT, or snow pit work. In the video referred above notice how easy the slab block glides along a well defined fracture plane produced by the PST failure.

Bottom line is that Pedro and I are being diligent in measuring the angles of every slope before skiing it, and making certain that we only ski slopes below 35 degrees in steepness, and that are not connected to steeper slopes either. Even in subalpine terrain the snow depth is highly variable, and the likelihood of finding a trigger point is not negligible. As an example, yesterday as we skinned out of a narrow valley bottom, with highly consequential terrain traps, I detected a hollow wind slab undermined by advanced facets. The slope was approximately 30 degrees, but it sends shivers along my spine, and I found myself rapidly but carefully skinning backward to safety. Notice that the wind slab was very localized, and it was created not by prevalent winds, but by cold air sinking along a steep narrow drainage!

The skiing was fantastic. But you knew that from the video. North aspects snow skied creamy with 20 cms of  dense and loose snow consisting of small facets. Aspects with sunlight were skiing much better, with a silky satisfying feeling typical of large diurnal recrystallized crystals covered by massive amounts of large surface hoar crystals.
Pedro & Chago tracks at lookers right. Diurnal recrystallized snow skiing!
In the above picture we can see a set of tracks to the left. This slope averaged 32+ degrees in steepness with a 34 -35 degrees roll in lower third. The party did not skied one at a time. Last December 2012 this same slope avalanched naturally during a surface hoar instability cycle. I hope members of this party read this: Pedro and I really loved your your uphill track. You did a superb job - very nice indeed. Pedro and I also enjoyed hearing your happy hooting after skiing the above west aspect slope. We really want you around. Please be safe, and follow nature rules. Always-Always-Always ski one at time in slopes steeper than 28 degrees!

Back to surface hoar - this layer is going to be next problem once they get buried. And it is unlikely that warm temps or wind can destroy all of the surface hoar now resting in top of the snow at Banners Summit area. Enjoy the sequence of pictures for surface hoar crystals observed yesterday.

Festival of Surface Hoar!
The weather was tranquil, with calm winds, with a very cold start in the morning around -10 degrees celsius. Temps at protected and northerly slopes remain cold. With regards to temps - the snow temp gradients for the snow surface at sunny slopes are dramatic;
  • T at surface  =  -15 deg-C
  • T at 5 cm      =  -18 deg-C
  • T at 10 cm    =  -14 deg-C
  • T at 15 cm    =  -10 deg-C
  • T at 20 cms  =     -8 deg-C
The gradients at the top 20 cm of the snow surface guarantees that diurnal facet recrystallization will continue unabated!
Skin transitions at creek bottoms looked cold and felt cold ... brr!
At sunny aspects the temps were just below zero degrees celsius. Very nice indeed for sitting down to enjoy snacks along with the splendid views.
Pedro relaxing!
Copper Mountain South Face - Nice ski tracks!
One of my favorite ski tours, south of Copper, we call it 9218.
We drove back to Boise after sunset, but not without snapping pictures of the always interesting avalanches at I21.

ID21 Avalanche Activity during mid-January
The day was concluded with a visit to the Idaho City famous Trudy's restaurant. Was this a perfect day or not?
Delicious pies!

Wednesday, January 15, 2014

Headwaters of Whoop-Em-Up Headwaters and Lamar Ridge - 1.14.2014

Tuesday was a perfect day ... bluebird day, no wind, temps close to zero degree celsius, and plenty of hero snow to be harvested!

We ski toured the Lamar ridge area at Pilot Peak. The polygon at the top of the topo map denotes a recent avalanche we will provide comments later in the post.
CalTopo for Pilot Peak - MCS
Due to the warm temps and clear skies, any slope at any elevation with any south has developed a devilish crust. I expect that slopes with East component will become crusty next. The other side of the coin, is that the snowpack is experiencing settlement and that might help in promoting the sintering of the problems weak layer now buried.
Clear signs of snowpack settlement (Not Whumpfing)
The snowpack below 6500 is 1 meter deep, at 7000 feet is 1.2 meter deep, and at 7800 feet it is 1.5 meter. At 7800 is unconsolidated, thus keep at least one ski on as you transition from ski to tour mode, or you risk sinking deep into the bottom basal facets. The snowpack produced only whumpfs below 7000 feet, where it appears it is easier to trigger a buried advanced facets in top of a crust at the 55 cm depth. At 7800 feet this layer is found at a depth of 80 cms.

Stability testing produced negative results for the 35 cm layer of near surface facets above crust buried by the last storm. But the advanced facets buried between 55-80 cm (depending on elevation) continue to produce energetic propagation with sudden planar failures (Q1). The ECT (Extended Column Test) failed to propagate a fracture at the 80 cm depth, but the layer of concern is deeper than the recommended weak layer maximum depth of 70 cm. ECT with weak layers deeper than 70 cms results in false stables. Testing  with PST (Propagation Saw Test) failed after moving the saw 25 cms along the fracture plane. The fracture propagated to the end of the column.

Notice that in the video, I do not let the ECT go wasted after it fails to provide evidence of propagation potential (due to depth of weak layer > 70 cms). In the spirit of searching for evidence of a structure favorable to propagation the snow saw is used to disturb the weak layer, and a fracture is initiated and propagated. Once the failure occurs, gravity takes over and the slab slips (slides) into my face ... pretty funny ... watch the video!

While performing stability test in the snowpit, the snowpack failed around us. The failure occurred at the 80 cm weak layer. Check the next picture with the snow saw next to the vertical crack. The vertical clean cut in the snowpack corresponds to the PST column we were isolating during the fracture.
Fracture failure while in the snowpit
We would have liked to ski the much steeper shots of the Whoop-Em-Up headwaters, but we kept the slope angles to less than 35 degrees, and repeatedly used our sight through inclinometers to verify that we were not venturing into steeper terrain. Recall that the snowpack has a serious structural weakness now buried at 80 cm and it is capable of producing destructive avalanches. AND few hundred meters away, the remains of an avalanche at that same layer of concern occurred during the last 48 hours demanded a conservative approach.
Avalanche starting zone at the 7700 feet - Whoop-Em-Up headwaters, Pilot Peak
We did not get close enough to capture a better picture of the avalanche , since we wanted to continue skiing, but we were able to notice that the avalanche ran at the weak layer of concern. The avalanche ran full length through the trees and was of destructive size 2, well capable of killing a person.

At most aspects and elevations, there is a delicate layer of surface hoar, and at slopes with southeast aspect the layer rest in top of a crust. This might become problematic if it is not destroyed by warm temps or wind prior to the next storm cycle.
Surface Hoar above the crust layer.
The views of sawtooth were splendid and Copper Mountain at Banner Summit could be easily identified.
Copper Mountain from Pilot Peak
As shown in the video at the beginning of this post, the skiing was fun. Next some pictures that showcase the skiing terrain we skied.

Next a view from Top of the World, Almost Top of the World, an dthe Summit Creek Glades from Lamar Ridge.
Almost Top of The World and Top of The World - Pilot Peak
Summit Creek Glades - Pilot Peak

We skied the Summit Creek Glades two days ago, and the carnage of the tracks can be seen. I would like to use this picture to point to a recurrent small avalanche, what we call a repeat offender. This avi path is in the shadows in th e upper right quadrant. Next a better picture
Small avi with nasty terrain trap at Summit Creek Glades
As you can see in the picture above, this small avi is located in nasty terrain trap. The idea is that you study these two pictures, and avoid this line during times of of avalanche concern.

Sunday, January 12, 2014

Pilot Peak was having a wumpfing Day on 1/12/2014

Today was a day of many whumpfs at Pilot Peak! The fractures, cracks, collapses, and whumpfs were too numerous to count. We experienced them at many locations, all aspects and elevations, open or wooded slopes.

The many white lines are cracks of a full slope that fracture, and compressions of slab pieces formed ridgelets.
Stability test results clearly confirmed the unstable conditions;
  • CTEQ1(SC) 30 cm down and CTMQ1(SP) 55 cm down.
  • ECTPQ1(SC) 55 cm down.
  • PST20/100(END) 55 cm down.
  • PST10/100(ARR) 30 cm down.
Numerous crowns of small avalanches were observed, however we were never close to steep and larger slopes of Pilot's Peak.
Avi crown at South Aspect
Avi crown at North Aspect
No surface hoar layer was identified today. The 30-35 cm weak layer consisted of near surface facets above and below a very thin crust layer. The 55 cm buried weak layer consisted of well developed facets above a 0.5-1 cm thick decomposing crust. At elevations below 6600 feet there was a crust layer from Saturday buried 15 cm under last night new snow.

The skiing was quite good! We only skied slopes between 30-32 degrees in steepness. Early in the morning we tested few small inconsequential slopes with 35 degrees in steepness, and their slab displaced after failing, That was enough for us to be very diligent in the use of our sight-through inclinometer to verify slopes angles at the various slopes and gullies we skied.

As the day progressed it continue to snow, and the conditions  progressed from tight to waist deep snow. Coverage was excellent, and we were able to ski down to Summit Creek, at the first switchback at Mores Creek Summit north side with no problems.

Next a short video for the day. You will see Pedro enjoying the soft snow conditions, and some short captions of an ECT and PST tests. PAy close attention to the ECT sudden collapse, and PST full propagation.

The next map shows where the summit creek glades are located in the Pilot Peak East ridge. Once the Mores Creek Summit snotel shows more than 1 meter, the ski lines on this area open up. Be mindful that although most of the terrain at the Summit Creek glades is moderate, there are pockets of steeper terrain with avalanche potential. Here is a link to the SnowGeek trip planning tool for this location: Pilot Peak.
Today's short ski tour of Summit Creek Glades.