Tuesday, January 23, 2018

Pilot, Sunset, Freeman Peak - Snowpack Update - January 23, 2018

First the good news!

The snowpack is slowly building up. Above 7000 the snowpack depth exceeds 1 meter. Locations with some north component have as much as 1.5 meters in depth. Skiing continues to be pretty fun. Below Nico, a Chilean IFMGA guide enjoying Freeman skiing last Monday (January 22, 2018).

The FIRST bad news - There was a rain event at all elevations in the Mores Creek Summit area Sunday night. The new 15-20 cms of new snow from Sunday night through Monday came down above a rain crust. This new layer will require some monitoring since it is likely to result in a melt-freeze facet recrystallization.

The SECOND bad news. Last Saturday there was a timber sled avalanche release at Pilot Peak bowl. I was unable to get pictures and only have second-hand reports from a separate snowmobile group the observed the triggering of the slide. It is likely that the release occurred at a surface hoar (SH) layer. Coincidently the SH layer was identified last Saturday at a depth of 65 cm. This SH layer is now buried between at an 80-85 cm depth after the Sunday night storm. This layer was not observed at Freeman or Sunset, but it was present at a Pilot Peak snowpit above 7400 feet at a slope with an NE aspect.

The surface hoar layer somehow has been fused by a melt-freeze event to the slab and underlying surface. The fusing and preservation of SH is a rare event I have not witnessed before. This thin "fused" SH layer is an unpredictable layer that shows propagation potential with stubborn reactivity. It was identified during a propagation saw test (PST) of the 90 cm facet layer. Fracture initiation of the 90 cm layer simultaneously triggered a failure at the 65 cm SH weak layer 😱. The SH fracture plane is shown in the next figure.

Third bad news - it is likely that we still have to deal with another cycle of instability once the snowpack is re-loaded again. There are two weak layers that will require our attention, in addition to the slide paths that avalanched two weeks ago. The weak layers were left in place, and new snow was redeposited. These areas have the potential of becoming "repeat offenders" once the recent snow has time to metamorphose and develop a cohesive slab.

Changing gears - Last Sunday we completed a Silverton Avalanche School PRO1 brought to Mores Creek Summit by Avalanche Science. We had participants from Japan, Chile, Colorado, Washington State, Idaho, and Maine. The PRO1, a new American Avalanche Association professional course introduced this 2018 Winter was planned to be held at Soldier Mountain Ski Resort, but it has to be moved to Mores Creek Summit due to lack of snow.

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We would like to take this opportunity to express our gratitude to the USFS-Idaho City District Range Office, Idaho City Library, and the Idaho City Chamber of Commerce. This PRO1 course would have not been possible without the support of those organizations.

Next a collection of pictures from the PRO1 course. Notice the cozy instructional facilities of Avalanche Science at its headquarters in the Idaho City visitor's center.

For those interested in Avalanche eduction at Mores Creek Summit, visit AVYSCIENCE.COM. There are NOW two types of Avalanche Level 1 course offerings; "Premium" and "Regular" Avalanche level 1 courses. Check AVYSCIENCE.COM for dates, prices, and what is included in each course.

There is a $50 discount on the course fees when donating more than $25 to the Payette Avalanche Center or for lodging at Idaho City during the course. Proof of donation/lodging is required to get the discount code. The discount code is redeemable at AVYSCIENCE.COM.

Last weekend I noticed that some ham radio enthusiasts used the 146.460 MGHz for their communications while skiing at Mores Creek Summit. What a coincidence! That is a frequency I monitor and communicate with when backcountry skiing. I suggest backcountry skiers adopt this frequency for Mores Creek Summit communications. That will allow for communications not only during emergencies, but to also share observations, snowpack data, stability test results, and other relevant information.

Friday, January 12, 2018

Avalanche Cycle at Pilot Peak (January 11-12)

Yesterday we ski out of Pilot past 2:00 PM. Signs of instability were present, but a natural avalanche cycle had not started yet.

We left the trailhead close to 8 AM after a beacon check and a discussion about conditions. Our tour plan was conservative considering the unpredictability of the buried persistent layer. As we gained elevation we noticed that yesterday blower powder was now cohesive and slabby. And the whumpfs reminded us about the ability of the snowpack to propagate fractures, thus we carefully selected ski lines.

Later in the morning, once we reached steeper terrain above 7000 feet, we ran into several D1 and D2 avalanches at various elevations and aspects. Yesterday we skied past locations with avalanches. Apparently last night during an incursion of temps above the freezing level that was enough to finally tip the scales, and initiate an active natural avalanche cycle.

Pictures tell the story of the instability cycle at Mores Creek Summit Thursday night and Friday morning.

There were crowns with a thickness of up 90 to 100 cm at popular backcountry skiing runs such as Almost Top of the World, The knob. We counted six significant avalanches that released naturally at popular areas.

Throughout the day there was no lack of significant collapses (Whumpfs), and stability test confirmed that there is still an active weak layer buried between 90 to 100 cm with the potential of human-triggered slides at slopes that have not avalanched yet.

Another layer of concern is a 35 cm storm slab that also released at various locations. Stability tests failed at that layer with easy scores and Q1 fracture character (sudden planar).
Many of the slopes that were not steep enough to slide experienced striking fractures.

The skiing was fun, albeit the face shot quality pow from the day before was gone. Check the next video.

PilotJan12_2018 from Santiago Rodriguez on Vimeo.

The forecast for tomorrow is for a warming trend. In the long term, this will help with the present instability. meanwhile, it will be prudent for tomorrow not to ignore slope angles and be selective where to ski in the MCS backcountry.

Next a slide show with pictures showing releases and fractures at Summit Creek area.

Pilot Jan 12 2018 from Santiago Rodriguez on Vimeo.

Thursday, January 11, 2018

Nice Pow day Today at Pilot - January 11, 2018

We left Boise early. Snowing intensity picking up as we approached Idaho City. By the time we arrived at Mores Creek Summit it was snowing at a rate of 2 cm/hr. At 6000 feet it is yet not looking like winter. But once you reach the 7000 it is a winter wonderland!

PilotJan11_2018 from Santiago Rodriguez on Vimeo.

By the time we were skiing there were 20 cms of new snow. Early in the afternoon, the storm snow reached the 30 cms.

The snowpack predictably was reactive after the new load. We observed numerous whumpfs. After checking the snowpack we suspect that the whumpfs were occurring at a new weak layer interface buried 45 cm below the snow surface. It is likely that this recent weak layer consists of a near facet layer form prior to last Friday's precipitation event when it developed the rain crust and it was subsequently covered by new snow. We do not know how widespread is this weak layer.
The Thanksgiving crust and facet weak layer is now buried 75 cm below the snow surface. The snowpit was done at 7400 feet, NE aspect, on a 22 slope angle. The Thanksgiving crust/facet weak layer was unreactive. At the snowpit, we did not find evidence of fracture propagation, but the Fracture Quality score of Q1 is concerning, particularly when considering the significant whumpfs we observed,

We will be providing another update prior to the weekend. The meager snow conditions at the pass might discourage skiers, but higher up there are good ridinconditionsns.

Notice that there are some NEW additions to the Mores Creek Summit Blog sidebar;
  1. Links are provided to facilitating getting the Avenza app for your mobile device. Another link is provided to download topo maps from Mores Creek Summit with slope shading. The Avenza and topo maps are free.
  2. Another set of links are provided for the season snowpits.
  3. The snow forecast generated by OpenSnow for Idaho is also available via a link.
The next video was filmed last Saturday at Peak 9220 - Banner Summit.

This peak is located SE of Copper Mountain. Skiing was good. We experienced whumpfs. Stability testing produced moderate results and no evidence of propagation. However, Q1 (Sudden Collapses) scores at a 45 cm weak layer are of concern. We did not find wind slabs at 9220.

Wednesday, January 3, 2018

Pilot and Sunset Peak - December 31 and January 2 Updates

The story for MCS continues to be the same;
  1. It is best to use the summer forest service roads to access Pilot or Sunset Peaks. The roads allow climbing above the 7000 feet in elevation. At that elevation, there is enough snow coverage to make skiing safe and keep the base of your boards healthy and scratch free.
  2. The persistent slab problem is let's say "persistent". Stability tests and slopewise collapses (Whumpfs) continue unabated. Snow pits for December 25, 27, 31 and January 2 are remarkably similar. 
  3. With careful selection, there are northerly aspects that continue to provide fun skiing. Other aspects have a variable rain crust making skiing instructional.
Below I included for illustrative purposes the snow pit profiles for December 25 at Pilot Peak and for Sunset Peak yesterday (January 2). With the exception of the surface crust developed last week and the densification of the top slab, both profiles are remarkably similar for two locations, particularly when the two snowpit locations are several miles apart and with somewhat different aspects. The first snow pit profile corresponds to Sunset Peak recorded yesterday, and the second to Pilot Peak last Christmas day.

The next video summarizes the propagation test results from January 2 at Sunset Peak. The ECT failed at 18 taps, while for the PST type of tests the fracture propagation was arrested after the slab fractured. The slab fracture for the PST and CPST (horizontal experimental test) at 60 cm after a critical saw cut of 25 and 23 cm respectively. 

SunsetJan2_2018 from Santiago Rodriguez on Vimeo.

We also experienced a significant slopewise collapse at the same slope we conducted the stability test.
Next a picture of the lookout at Sunset Peak. My hope is that the picture motivates the reader to make a trip over to the lookout.
Yesterday we were delighted with Sunset Peak views. The next picture is from the Sunset Lookout looking Southeast. Steel Mountain, in the Eastern Boise Mountains, can be seen in the background.
The next picture looks west from Sunset Lookout. Freeman Peak covers most of the view. Freeman has two drainages facing East, and they cover a large area filled with fabulous skiing. To the South is the 12-mile creek drainage and to the North is Mores creek (north) drainage with Pilot Peak road north of it.
At the end of the day, we were rewarded by a phenomenal sunset after ski touring Sunset Peak! :)
Two days earlier we ski toured Pilot Peak and skied Almost Top of the World, the lookers right side of Top of The World (shady lower angle northeast aspect terrain), and the Whoop-um-up creek headwaters. It was disturbing to see so many rocks at Whoop-um-up creek headwaters. In 25 years I have never skied there with so little snow. Whoop-um-up creek headwaters is a steep area with a cornice and avalanche path hidden out of the way from skiers typical tours. If you choose to visit it, please treat its slopes with ample respect during periods of instability. The next video summarizes well my last tour of 2017!

PilotPeakDec31_2017 from Santiago Rodriguez on Vimeo.

As an avalanche educator, I understand the challenges of trusting stability test results. The secret is in the doing. It is about getting used to completing two CTs, and ECT in less than 15 minutes (including digging). And it is about learning that stability tests are not the only piece of data - That way the pressure is off. When you are doing tests early in the season you are getting a fundamental understanding (and feeling) of how the snowpack evolves. Doing snow pits is like taking the "vital signs", it seems boring at first, you do it when the patient is not sick, but then, the value is when the vital signs change and you are able to recognize that something is "not right"!

And it gets easier to integrate weather, temps, wind, and precipitation to anticipate avalanche type and trigger likelihoods. And you will be surprised that as the winter progresses you are actually doing fewer stability tests and relying more on other observations. In the spirit of encouraging the blog readers to play (yes play) with snowpits, I include one more video with the stability tests performed last December 31st.

StabilityTestsPilotDec31_2017 from Santiago Rodriguez on Vimeo.

Finally - I wish to this blog reader, the most wonderful NEW YEAR!