Saturday, December 24, 2011

Post Christmas Present - Wx Change = SNOW!

Late Christmas Present is coming!

A major weather pattern change will shift the jet stream further south bringing a good chance of rain and snow to the region between Christmas and New Years Day. Expect accumulating snow in the mountains and rain in the valleys beginning on December 27th.

548 AM MST MON DEC 26 2011

548 AM MST MON DEC 26 2011 /448 AM PST MON DEC 26 2011/






Snow Probabilities of 4 inches or more for 12.27-28.2011

Be mindful that NEW snow will be falling in top of a very weak snowpack.

Pay attention to wummpfs and collapses. Do not ignore avalanches, even small ones at road cuts on your way to your favorite ski touring destination.

The snowpack in our region is heavily facetted and it will be experiencing changes in temperatures and loading (rain, new snow, wind transported snow, total storm snow deposition). Remember, the new NEW snow will become a slab in top of a weak layer of facets.

Snowpacks becomes reactive when experiencing fast strain rates. And this weather change promises conditions that will strain the snowpack.

We will know by next weekend how much backcountry skiing and ski touring will improve with more snow. Below the outlook for the next weekend, if these prediction holds we should see more snow through next weekend.

6-10 Day Precipitation Outlook
Dec 31 2011- Jan 4 2012

Monday, December 12, 2011

Cape Horn Ridge - Point 8995 - 12.11.2011

Gorgeous views from any high point at Banner Summit Sunday December 11 was the rule. Most high peaks from surrounding ranges could be easily identified.

Top of Cape Horn ridge first false summit at 8995.
Copper Mt. in the background to the left.
The skiing off the 8995 feet high point in the Cape Horn "horse-shoe shaped" ridge, just across I21 and North-west of Copper (8965 feet) was phenomenal.
East Facing basin below 8995 point  Cape Horn Ridge.
The snow surface at East facing slopes was soft and creamy. It only took telepathy to execute turns on such high quality "hero" snow. And the massive amounts of near-surface facets had a healthy "frosting" of "surface hoar"!

Surface Hoar at East Aspect at 8400 feet.
As we discussed in a previous posting it is always a good practice to plan a tour. The map illustrates the ridge we used for the skin up, and the intended ski lines.

8995 Point - Cape Horn Ridge Topo Map
We decided not to ski the SSW lines denoted by purple lines, and stick with the NE and E aspects. The skiing was "way too good" to gamble with a melt freeze crust at south aspects.

We started the tour by listing the snowpack concerns in our Blue Books (Snow, Avalanche, Weather, Observation Journal):
  • Windslab in top of facets
  • Unpredictable thin snowpack with basal facets (depth hoar)
  • And buried obstacles
At 8700 feet we identified a very hard windslab in a steep north looking slope. This thick slab was sitting in top of facets, and it was spooky with its drum like sound and dark appearance (shaded due to winter low angle of the sun). This slab very likely was the result of the strong North winds a week ago. A snow pit 30 meters away but at a less steep slope (34 Degree) and on a spinal ridge facing East produce a snowpit the following elements:
  • Surface - 1 cm - Hardness: Fist (F), Surface Hoar (SH) 3-4 cm crystals
  • 1 - 30 cm - Hardness: F, Near Surface Facets (NSF) 2 mm crystals
  • 30 - 50 cm - Hardness: 4 Fingers (4F), Mixed Facets 1 mm crystals
  • 50-52 cm - Hardness: F, Depth Hoar (DH), 2 mm crystals
  • 52cm - Soil, rocks, dirt ...
It is easy to recognize that a slab (hardness of 4F) is sitting in top of a weak layer of DH (hardness of F). Also, that the snowpack is shallow with a depth of 50 cm!

The gradients were in excess of the 1 degree per 10 cm as it can be seen below:
  • Ts = -3 deg-C
  • T10 = -6 deg-C
  • T20 = -6 deg-C
  • T30 = -4 deg-C
  • T40 = -2 deg-C
  • T50 = -1 deg-C
The numbers next to T denote the depth below the surface. Notice that there is a 3 Deg-C per 10 cm gradient at the top of the snowpack surface. That gradient explains the formation of Near Surface Facets. In addition there is a 1 deg-C per 10 cm gradient at the bottom of the snowpack, that is responsible for the formation of basal facets we call depth hoar. It is not hard to realize that during the night, the top of the snowpack will see temperatures below -10 deg-C reverting the gradient in the top of the snowpack. We call this type of Near Surface Facet process Diurnal Re-crystallization.

I felt it was appropriate at this time not to chart the profiles and temps, but to show that charts are not a pre-requisite for understanding the data, and the purpose of this write-up is to assit folks in making sense of the data that can easily be collected in the field.

Stability tests at the East 8700 feet slope with 34 degree slope produced the following results:
  • ECTN29Q3 at the 50 cm DH layer
  • CTHQ3 at the 50 cm DH layer (3X - 3 times)
  • PST 80/100 END
In a previous blog posting we discussed the Stability Quadrants. The above data can be summarized in the following format:
  • Trigger Likelihood: Low
  • Propagation Likelihood: Low
  • Slip/Slide Likelihood: Low
  • Structural Weaknesses:
    • Presence of slab: 4F Slab in top of Fist hard DH weak Layer
    • Weak layer below top 1 meter - 50 cm
    • Weak layer thickness is thin - 2 cm
    • Difference in slab and WL grain sizes - 1 mm
    • Weak layer composed of persistent grain type - DH
Even when the stability tests failed to find "instabilities" and could provide some comfort, the snowpack in our area is thin and very variable. It only takes some old patch of early snow to be buried below the facets to provide the much needed missing component to change test results. Or the formatin of heavy and hard windslabs in steep terrain, such as the one we found. I also still remember last week, when at Angel Basin (Anthony Lakes-Oregon) I found a similar snowpack with PST 40/100 End results, suggesting a high likelihood of propagation potential (propagation when less than 50% of full length is cut). The only difference is that the November snow was deposited above an isolated patch of October snow.

Since the snowpack is thin, it was very easy to check if the structure of the snowpack was changing as we skied. In addition we avoided the deep north steep slopes with windslab!

Saturday, December 10, 2011

Sunset Peak 12.10.2011

This blog is named after Mores Creek Summit for one reason ... and it was about time for me to hang around Idaho City Mountains this winter. This is my season first visit to Mores Creek Summit backcountry, and I was very pleased with the skiing. The coverage is thin, but the re-crystalized snow is not skiing bad at all. Of course, it helps when you own rock skis, and they have been hammered during the last 4 weeks of BC skiing.

Considering the snow depth of 20+ inches reported by the Snotel at Mores Creek Summit, I set my sights on Sunset Peak, and took advantage of the logging road to avoid the lower elevation brush.
Mores Creek Summit Snotel for the last 30 days.
It was a clear, sunny, and relatively warm day (0-2 Deg C). I was surprised no other folks were touring Sunset Peak today, but there were enough old ski and snowmobile tracks suggesting that it has been popular during the last week or so.

Last week while ski touring Copper Mountain-Banner Summit, Angel Basin-NE Oregon Elkhorn Mountains and Brundage Mountain, surface hoar was not present in the areas we toured and skied. That was not the case today at Sunset Peak, there was an ample supply of surface hoar (SH) at W, S, E aspects at elevation above 7000 feet. Most of the snowpack has been transformed into facets, and I am not looking forward to have this SH layer buried in top of another layer of facets that has experience settlement and densification without experiencing significant sintering. In other words, the SH will be sitting in a weak layer capable of becoming a fracture failure surface once we have slab sitting in top of the buried SH.

As mentioned earlier, the snowpack was thin at Sunset: 30 cm at 7000 feet, and 50 cm at 7700 feet. It helps that the snowpack is dense and facetted, otherwise the lack of a base would have been problematic to the ski bases and skiing in general. I should mention, building an uphill track on facets has the added benefit of testing your skills in setting appropriate angles and providing an extra work-out that will pay-off later in the season.

Today was a relatively warm day, with south winds that did not mitigated the significant facetting the snowpack is experiencing;
  • at 7000 feet; West aspect; Ts = -8 Deg-C, T10 = -6 Deg-C, T20 = -3 Deg-C
  • at 7700 feet; North Aspect; Ts = -8 Deg-C, T10 = -4 Deg-C, T20 = -3 Deg-C, T30 = -1 Deg-C
For both locations the gradients were much higher than the critical 1 Deg-C per 10 cm. This is the reason that the WHOLE SNOWPACK is turning into facets. In addition, it explains the ECTNQ3 - 40 cm down (DH, facets), when the snowpack lacks a defined slab structure.

Although most of the wind breakable crust lower in the mountain (below 7600 feet) has disappeared due to faceting, there is still some resilient thin breakable crust surfaces at NW, N, NE aspects close to Sunset Peak summit. I can handle buried obstacles, but this summer I skied breakable "cardboard" wind crusts at Las LeƱas to last a lifetime, thus I am determine to stay away from any crust this winter!

I will go ahead and publish this posting, but once I get back later tonight from a Christmas Party I will post a video from today's tour and skiing. The views were phenomenal!

Tomorrow, might be a good day to explore some stuff near Copper Mountain. Keep checking the blog!

Friday, December 9, 2011

Brundage 12.6.2011 and Transcievers Selection

Lick Creek Range from Brundage 12.6.2011
Gary - Brundage 12.6.2011
Chago - Brundage 12.6.2011

Brundage as most of SW Idaho is low in snow, but the skiing is not bad at all. Late in the afternoon I skinned up and skied a single run with friends. Conditions were better than I expected, and with proper selection it was possible to ski untracked lines with 10-15 cm of soft pow in a good base and avoid buried "mines".

One of my companions had a loose binding, he had to ski down on a single ski!
Notice the bright moon.

Earlier this week I had the chance of spending the day with University of Idaho graduate students talking about the Science of Avalanches. During the morning we meet at the MOSS campus in Ponderosa State Park, and we finished the morning simulating flour (slab) and sugar (weak layer) avalanches in an inclined board.

In the afternoon the graduate students had the chance to dig snowpits at Brundage, look at facet crystals, perform stability tests, and practice with transcievers.

The Brundage snowpack at North and West exposures is shallow at 6000 feet, with no more than 50 cm at the deepest location. North aspects have a snowpack that is mostly faceted, and with some layering but very little hardness (or cohesiveness) difference between the layers. West aspects showed a more settle snowpack with round grains in the bottom 30 cm, mostly small facets above the 30 cm depth (from the ground). The top 10 cm (40 to 50 cm surface layer), consisted of mixed grains (facets showing rounding). Stability tests did not find evidence of instability.

Several students were interested in transcievers recommendations. And during the last few weeks many friends and acquaintances continue to ask for guidance in the purchase a transceiver.

The above slide set summarizes the statistical analysis I performed for a transceiver company. The results are very clear, Analysis of Variance did not detected statistical difference in search perfomance between transcievers manufacturers/brands for novices as well as Guides. However, the Ortovox F1 included in the Box & Whisker charts (bottom chart) did not performed well in the rescue scenario, and I removed that transceiver from the ANOVA (top chart).

In summary, this study suggest that any of the 2 and NEW 3 antennae transcievers will result in good search times, and brand selection is a personel preference. Also it documents that novices can improve times with rescue practice in order to reach comparable search times  attained by "Guides".

For advanced recreationists, avalanche professionals, and mentors/instructors. I strongly recommend to acquire a 3 antenna transceiver. The motivation is that this user has influence on his peers, and it is important to model behaviors as well as rescue gear we want students and ski companions to own.

The most important characteristic of a 3 antenna transceiver is it ability to greatly suppresses the dual minimum when transcievers are coupled (antennas have same orientation). This is not critical for a well trained professional, but it is important for novices. And the best way to encourage novices to acquire a 3-antenna is not to brag how well a pro can search with old gear, but to be a role model, and own a 3-antennae transceiver.

Monday, December 5, 2011

Trip Planing and Stability Assessment Quadrants - Anthony Lake BC Tour

"How do you plan a backcountry ski trip? This is an important skill to refine. Trip planning allow you become acquainted with the area you plan to tour, identify the best snow conditions for riding, and anticipate instabilities.

Last Sunday December 4th a group of friends from Boise ventured to visit Anthony Lakes (YES - the resort is OPEN!). My friends have not been to Angel Basin before, and I was stoked to show them the superb ski lines and wonderful POW that can be at a sub range named "Little Alps" in the Elkhorn Mountains of Eastern Oregon.

When planing a tour, first you need to produce a topo map from the area:
Anthony Lakes and Angel Basin Topo Map

Red and blue lines are uphill tracks and yellow and black lines downhill tracks. Yellow lines are some popular lines I have skied before.

We were concern about the effect of wind on N aspects, thus we kept the option open to ski a south aspect slope to the center-right in the topo map. The black line denotes a future line we dream about doing in the NEAR future.

We printed enough copies of this map with UTM coordinates (easier to read and work with) for each of the party members.

Unfortunately there are not many pics available from this area, and the various times I have skied there, visibility has been poor. But there are two pictures from that shows our two intended destinations.

Lee Peak in the Left, Lookout Mountain in the right.
Gunsight Mountain
Next we googled pictures and review area using google earth.

Lee Peak in the center, Lake Lookout Mountain to its left.
This "aerial" google picture from 1994 shows the area we intended to ski ... pretty much the center left line below Lee Peak (Lee is in the center).

Angel Peak-Left, Lee Peak-Center, Lake Lookout Right.

Above another google view from the same area but created in 2005.

View to the North from the Top of Lee Peak. Gunsight Peak in the center.
Google view from the top of hat we plan to ski (Lee north aspect shoots). We skied the looker saddle in right of gunsight peak.

Next we check any information available through the resort and Wallowa Avalanche Center:

Wallowa Avalanche Center

WAC Backcountry Ski Reports

WAC - Anthony Lakes Link

Anthony Weather Station

From these links we found sufficient information for us to start building a "picture" on the conditions:
  • Temps durin the 24 hours prior to our visit were in the  -9 to -4 Deg C with moderate winds from the NW trending to calm in the evening, cloudy skies and no precipitation.
  • Weather forecast of partially clouded skies clearing up in the afternoon, with moderate NW winds, and temps for the day in the range of -8 to -10 Deg C.
Based in the information we identified two concerns:
  1. Wind slabs in top of depth hoar in a shallow snowpack.
  2. Rocks and many buried obstacles.
Since a problem becomes a concern (a very "good" thing) when an action plan is developed, or "something is DONE about the problem". Otherwise, you might end up stuck in an escalator (figuratively speaking): Video of Two Stuck in a Escalator :)

We took note, and planned to pay close attention to aspects that might have been loaded with snow due to the moderate wind recorded Saturday, and the strong winds forecasted for Sunday. In addition we came prepared with "Rock" skis to address the buried obstacles concern.

By 8 AM we were at the resort, and after a routine stop to visit my friends with the Anthony Lakes Ski Patrol, we skinned up to Angel Basin. The snow was soft, but it was obvious that there was not sufficient snow to cover the very abundant granite!

A couple hundred feet below Lee Peak Summit we found a snowpack between 70 to 90 cm in depth. A snow pit in a 36-38 degrees gully with wind blown & new snow above old snow produced CTHQ2 results at 35 and 50 cm below the surface. Three CT failed at 50 cm, and one at 35 cm. Both layer interfaces (35 and 50 cm) consisted of weak layers composed of ~1mm near surface facets (NSF) crystals and mixed grains starting to round and sinter.

It should be noted that, similar to the snowpack in Copper Mountain - Idaho, we did not find basal facet layers (Depth Hoar - DH) at Angel Basin's North or South aspects.

A PST fracture propagation test at a 50 cm weak layer failed after a 40cm saw cut, suggesting that the weak layer & slab structure buried 50 cm below the surface have a fracture propagation potential.
Stability Assessment Quadrant

The Stability Quadrant shown above is a structured method use to assess slab avalanche stability.  This method facilitates the review of the evidence we found of instability - "there is a high likelihood that a fracture failure will propagate if we were to find a weak trigger".   Where we dig the pit the likelihood of a trigger was low (hard score), but as we continued touring and skiing, we were mindful about conditions and configurations that will augment the trigger likelihood, such as additional loading or thin spots in the snowpack.

The slip likelihood, is the last stage during an avalanche fracture failure, and it is a function of slope angle. The Q2 results suggest that there is a moderate likelihood of a slide once a fracture is initiated and propagated in the slope angles we tested. This information allow us to manage terrain angles and continue searching for more information (handpits, quick-pits) to avoid areas that might have a high likelihood (Q1 scores) of slip.

Finally, we identified structural weaknesses that assisted us in tracking the snowpack during the day; weak layer buried at 50 cm, a thin (less than 2 cm) weak layer with persistent grain types (NSF), and an identifiable slab (harder snow or slab in top of weak layer). As we travelled in Angel Basin, it was obvious that the slab structure was not present everywhere, and that was an important fact in the selection of slopes to ski.

During a slab avalanche there are three distintive phases; fracture initiation or nucleation (triggering), fracture propagation (due to propagation wave), and slide/slip of slab. Once the fracture failure occurs gravitation (weight of slab) and coefficient of friction between slab and weak layer (above gliding surface) takes over. This theory has replaced the now obsolete shear theory, and it has been validated through many studies. The stability quadrant shared above is a reflection of the NEW "Anti-Crack" fracture theory being applied to stability evaluation.

The ski down Angel Peak was fun, and not much later we were climbing up to Gunsight Mountain via the south face. The snowpack on this aspect was shallower (not a surprise) and "contact" with rocks during the ski down was much higher. :)

There are no pictures to share from this trip. The weather forecast did not materialized, and the skies remained obscured, with the mountain shrouded in clouds and fog all day- like skiing in a glass of milk!

I thought hard about not a posting a BC skiing area well away from Central Idaho Mountains. However, this is a great opportunity to share good practices with the Mores Creek Summit Skiers Community. This blog posting  briefly covered trip planing and integration of weather in identifying concerns, as well as reviewing a methodology to asses snow stability.

Finally, The Elkhorn Mountains near North Powder and Baker City are abundant with BC skiing possibilities, that will delight Idaho BC skiers. One of the best advices I received MANY year ago was to ski in as many different snowpacks as possible to improve my avalanche terrain travelling skills. A vist by Idaho BC skiers to Angel Basin will provide opportunities to assist in the growth of your avalanche terrain travel skills as well.

Happy skiing this weekend!

Saturday, December 3, 2011

Copper - Saturday 12.3.2011

Saturday morning, Copper Mountain at Banner Summit woke up to a clear day with calm winds but very cold temperatures. The temperatures at 7400 on the western ridge leading to the top were -10 Deg-C. Snow surface temps were at the snow surface recorded -20 Deg-C. Also temperatures at 10 cm and 20 cm below the snow surface were -10 Deg-C and -6 Deg-C respectively. Most definitely gradients in excess of 1 deg-C per 10 cm! And it showed by the variety of near surface facets and advanced facets in the snow surface at all elevations and aspects. Surface hoar was not observed today in the snow surface.

Stephen at Copper Mountain, NEE 8600 feet before skiing recycled pow.

Snowpits at ~ 8600 feet of elevation at NEE  (38 deg slope steepness) and SSW (28 degrees steepness) aspects did not revealed any weakness with multiple CTN and ECTX scores. At 8600 feet of elevation, NEE aspects had a snowpack depth (HS) of 80-100 cm, and SSW aspects had a HS = 50-60 cm. Both snowpacks had a progressive hardness from F (5-10 cm) to 4F to 1F. No basal facets (DH) were observed.

A quick-pit at NNE aspects, 8500 feet elevation, in a steep open meadow surrounded by trees, we were surprised to see a snowpack depth much shallower than expected, with HS = 40 cm. The whole snowpack in the mostly north aspect slope had turned into advanced facets. But the skiing was not bad at all!

One of the NEE slopes we skied.

Below a very short video of the slope shown in the picture included above. Too bad we could not get more footage - the cold temps messed up the cam, and it refused to cooperate!

The West, NW, and north aspects were severely affected by the wind with a mix of wind crust, and wind erosion features. These surfaces did not make for fun skiing!

However, with careful selection at S & SW aspects and NEE and E aspects it was possible to find fun lines to ski with 10-15 cm of soft pow. Below 8000 feet at aspects with any south, a nasty melt crust reared it ugly head. We learnt very quick to retreat to more treed slopes when skiing South aspects.

In general, coverage at Copper was adequate, buy it still requires some level of vigilance to avoid some buried obstacles.

There were other folks in the mountain, but we never ran into each other. I should note that it was a pleasure to run into Ralph (one of the blog contributors) for the first time this year at the Bench Creek pull-out. His tribe were heading over to Bull trout point. I will be looking forward for his report.