Thursday, December 31, 2009

December 30th - Skiing at the Glades, Pilot Peak

Happy New Year!

I wish the best to all of my friends and readers of this blog. Without you this work will be meaningless, and I am appreciative of your support and encouragement during the last two years. As I get to personally meet many of you, and how this blog played a role in becoming friends, it re-energize me to continue sharing my experiences and observations.

Now, if we can get others to also share their experiences in the Idaho Mountains while ski touring and backcountry skiing, that will be AWESOME!

The skiing at the Glades (Pilot Peak) was superb. Please refer to a map posted in the blog few days ago:

Pilot Peak Topo Map

During my first ski run I made the mistake of using sunglasses, and I suffered the consequences by having my eyes sandblasted by jets of cold snow from the face shots. The rest of the day I was glad to have goggles buried deep in the pack.

By noon there were 30 cm of new snow. The temperatures were cold all day (minus 5 deg-C), and the snow came down without the effects of wind (Winds were light from the South in the morning, switching to light winds from the North in the afternoon). Thus the combination of relatively cold temps and light winds, resulted in "cohension-less" snow we dream about skiing every day.

Below, not a great movie clip, but it gives an idea of the fun conditions.

It was another wonderful day in company of new friends (Brian and Trevor), and my son Pedro. And we skied until we ran out daylight.

Due to low density nature of the new snow, the "SKIING" penetration was deeper than the 30 cms, and we were still sinking into the layer of "near surface facets".

It was also GREAT news not to have a slab sitting in top of the surface hoar that was buried with the new snow. Due to the lack of winds and/or warm temperatures, the surface hoar (SH) observed everywhere at Mores Creek Summit was not destroyed. Careful inspection of the snowpack reveled that the surface layer was present, but inactive under the low density thirty centimeters of NEW snow.

Stability tests done yesterday confirmed that the "basal" weak structure it is still a concern, with moderate Compression Test (CT) scores, but Q1 shear quality. A second CT at a different location (same aspect & elevations) did not failed after 30 taps. This confirms that we are dealing with a severe case of spatial variability, or simply visualized as a "mine field" scenario.

The surface snow (30 cm depth ) revealed CT results in the CTV and CE range with Q1 and Q2 results. ECT for the surface were negative. These results are not surprising due to the presence of SH. But the keep in mind that yesterday snow was in the very soft slab to not-slab range, and it is hard to get reliable CT/ECT results with very soft slab conditions. Ski cuts performed during the day were negative.

An observation of interest was finding a delicate thin crust layer at 40 cm of depth. This layer was capped by 10 cm of NSF, SH, and the 30 cm of new snow. This thin crust was detected at a NE aspect -7400 feet. It is NOT widespread, and it was observed only once. Just another piece of data suggesting conservative decision making.

When considering the basal weak structure and presence of surface hoar (SH) under the new snow we carefully selected slopes below 35 degrees. The ski lines we skied yesterday top at 32 degrees in steepness. Even when we search hard to find "warning"signs, we did not find any indication of instabilities.

The non-slab nature of the new snow allowed us to enjoy the skiing. But that is not going to last for too long. The forecast calls for moderate winds out of the South starting this afternoon, a significant warming trend during Friday daytime, and possibly wet snow precipitation at the 7400 feet level for Mores Creek Summit area. Notice the rain predicted by the models during Friday afternoon.

As wind, warm temps, and additional significant precipitation (with possible rain) start to have an impact on the snowpack it is reasonable to expect the formation of surface slabs that will activate the surface hoar existing under the snow at Mores Creek Summit. Meanwhile, there is a "deep instability" buried at the bottom of the snowpack that has not gone away. I said this before, it is important to make conservative decisions for this very unusual snowpack.

Finally I want to encourage "Mores Creek Summit" backcountry skiers to help with the economy of small Idaho towns. I understand times are though, but stopping at the local ice cream parlor, restaurant, or groceries stores in Idaho City will go a LONG way to get support from the locals. It really fills my heart how welcoming the locals are, and how they remember names and faces from the previous ski season.


Monday, December 28, 2009

December 28th - Winter Corner

Today we had another wonderful day backcountry skiing in the Mores creek Summit area. It was a relaxed day with two friends ski touring for their first time. Winter Corner is a perfect place to introduce individuals to backcountry skiing due to its easy access, so it was decided to spend half a day there.

The surface hoar I observed during Christmas Day continues to build up, and the crystals are getting pretty big. Check the following sample of pictures my son Fritz and I snapped during the day.

We observed strikingly large deposits of surface hoar (SH) everywhere, and it seems to be present in every aspect and at all elevations in the Mores Creek Summit area. Any open slope, meadow, or snow surface that is exposed to the clear and cold dark sky of the night has advance formation of large surface hoar crystals. These crystals are notoriously dangerous when buried, and slab avalanches associated with surface hoar can occur in relatively shallow angles and be remotely triggered from far away. Be mindful that once the SH layer is buried, because it is a persistent weak layer, and considering the large sizes of the surface hoar crystals, it will take considerable time for the snowpack to get rid of it.

The skiing was fine in open slopes due to the "near surface faceting" (NSF) or recrystallized snow. But treed sections in the slopes (shaded from the night sky, thus snow NSF metamorphism is hampered) were crusty or had a breakable crust that made skiing unpleasant. So, until we get more snow, ski in open slopes, that is where the best snow can be found.

If you watched the above video of my friends doing their last turns of the day, near the bottom of the hill, it is obvious that at the 6000 feet level it is BRUSHY! If you want to get out of the brush, go for longer tours, and ski above the 7000 feet level.

During my latest backcountry skiing outings I had the opportunity to check the snowpack structure for North, East, and South aspects. Today we digged a snowpit on a NW aspect with no remarkable differences from N and NE aspects:
  • snowpack depth less than a meter deep.
  • extremely weak basal structure 65 cms below the snow surface.
  • fracture propagation potential on the basal weak layer below the December 17 new snow slab.
Compression test results at the NW aspect and 6500 feet elevation evaluated were surprisingly "easy" (CT with scores of 2 and 3) with "sudden collapses". In addition a fracture propagation test [PST 20/100 (END) 65 cm down] suggested that the weak basal structure is still capable of propagating an energetic fracture accompanied with a "sudden collapse".

A finding of concern was a thin and subtle melt-freeze crust under the top 10 cms of NSF snow. I did not find this crust layer at N or NE aspects last December 25th. But the combination of a thin crust layer at West aspects, a layer of NSF, and a topping of surface hoar is a perfect set-up for avalanches. We are just missing the slab, but if the weather predictions hold, we might have a slab by the weekend. So as the winter progresses - we will have to carefully track this complex combination of weak layers and make conservative decisions.

During yesterday tour we noticed that the most visible ski lines at Pilot and Freeman are getting tracked. Fortunately a snow refresh is coming starting tonight, and continuing on Thursday. And elaborating on tracks - we noticed the MANY tracks at "Top of the World" bowl from snowmobiles. We need to politely and in the MOST friendly manner explain to our friends snowmobilers, that "Top of the World" bowl is not within the boundaries for their use. And they can access easily a lot of more terrain minutes away to the West of Pilot Peak.

That's all for today.


Sunday, December 27, 2009

Mores Creek Summit Info - December 27th

Yesterday we started the season with the first "Mores Creek Summit Backcountry" and "Winter Conditions; West Central Idaho Mountains" blogs posting. It was remarkable to learnt that people are finding NEW ways to have fun! Check the posting from Ralph at "Winter Conditions; West Central Idaho Mountains" blog. Play the video of the Igloo they built on the Freeman Peak ridge. SUPER COOL!

This Sunday morning, December 27th,  I am heading over to do some exploring around the Mores Creek Summit area, I will post "beta" on the latest conditions tonight.

 If you have NOT reviewed and carefully read the latest avalanche forecast for Southern Western Idaho, the snowpack synopsis, and discussion supplied by the Payette and Sawtooth Avalanche Centers advisories, PLEASE take time to do so. The links for their latest advisories are provided below:

Payette Avalanche Center

Sawtooth Avalanche Center

Those visiting the Payette Avalanche Center (PAC) website, will be pleasantly surprised about the significant improvements for this season. John, Dave, and Alpeh have done a remarkable job.

With this posting I will share additional information about the snow conditions leading to the"deep" instability we are observing at Mores Creek Summit (and surrounding areas) snowpack.

The next three charts correspond to Mores Creek, Big Creek, and Banner Summits, notice the "Snow Water Equivalents (SWE = amount of water) and/or snow depth. These charts are representative of backcountry areas frequented by Boise area ski tourers. Basically a shallow layer of snow sat for three weeks starting in late November through mid December. This period was characterized by clear weather and cold temperatures that promoted the development of advanced and large facet crystal through out our local mountains. Heavy snow precipitation resumed during December16-17th burying these "persistent" facet crystals.

These large facets and angular crystals in the OLD snow have a structure that makes molecular bonding with the NEW snow, composed mostly of small rounded and fragmented grains, very difficult. The bonding process has been further inhibited by the large difference in crystal sizes between the slab (0.5 mm) and facets (2-3mm). Thus, we should be prepared to be dealing with this "deep instability" for a  long while!

The above charts are updated weekly and are available at:

SNOTEL Snow Depth and Water Content Graphs in Boise Basins 2010

SNOTEL Snow Depth and Water Content Graphs in Weiser and Payette Basins 2010

As I noted in yesterday's blog posting, we need to be mindful of the Mores Creek Summit areas that released during the December 17th "Natural Avalanche" cycle. The snow cover for these avalanche starting zones and avalanche paths are now much thinner now (30-50 cm), and are more susceptible to faceting.

To ease the tracking of areas that recently released, I include below three topo maps with recent avalanche releases colored in yellow. Areas where naturals releases were expected during December 17th natural avalanche cycle, and/or that I have observe avalanche releases over the last 18 years are colored in red. Do not forget that south aspects in the topo maps were not a problem during December 17th avalanche cycle. I should note that NOT all areas with potential to slide are included in the topo maps. That will be an impossible task, and winter travelers need to manage terrain, evaluate conditions, and practice safe travel at all times.

Pilot Peak UTM Topo map:

Freeman Peak UTM Topo map:

Sunset Peak UTM Topo map:

Any pictures and/or observations of avalanches during the last instability cycle are appreciated, since it will greatly help in keeping current the Mores Creek mapping of likely avalanche paths and slopes.

In the past I had requested feedback through the Blog on the name used by some of us for the Mores Creek Summit ski runs. The above topo maps list some names for popular ski runs (green traces) at Pilot, Freeman, and Sunset Peaks areas. Feel free to suggest more compelling names! The red traces are for typical up track routes.

One more detail, the topo maps are printed in UTM coordinates. These coordinates are better for navigation in the ground, and for reading directly from the maps coordinates to be shared through the blog, or even in the case of an emergency.


Saturday, December 26, 2009

Feliz Navidad!

Feliz Navidad! Merry Christmas!

On Christmas day Pedro (my son) and I ski toured Pilot Peak in the Mores Creek Summit area. It was a strikingly beautiful day; blue bird day, light  to calm winds, and sweeeet snow. The skiing was fantastic!

Below a short video of Pedro skiing the mellow terrain at Lamar Bowl.

Get out and enjoy the conditions, there are many meadows, mini-bowls, ridges and lines waiting to be skied. The snow coverage below the 6500 feet level is light (read "BRUSHY"!), but above the 6500 feet level it progressively gets better with snow depths above one meter above the 7500 feet level.

Cold nights and warm days (below freezing level) have favored the formation of a thick layer of "Near Surface Facets (NSF)" at NE, E, SE, S aspects above 6500 feet. Diurnal recrystallization faceting is responsible for transforming the recent snow into facets, the results of very steep gradients during the day and nights. The snow surface gradient was estimated to be ~ 80 deg-C/meter (8 deg-C/10 cm) when measured at 7500 feet on a NE aspect slope above Lamar Bowl by mid-morning.

This layer of NSF is what some people call "Wild Snow", it is skiing fantastic, and we should enjoy it before it becomes a problematic layer once it is buried by snow. In addition to NSF, we observed significant areas (N,E,S aspects) covered in Surface Hoar (SH).

If these two layers (NSF and SH) are not destroyed by wind & warm weather prior to the next storm winter, it will mean that winter recreationists will have NEW layer to worry about in addition to the existing interface between last week NEW snow and old faceted snow. This layer interface was responsible for a very active Natural Avalanche cycle during December 17th, that resulted in a snowmobile fatality in the Cascade-Long Valley West Mountains. This very problematic buried layer was identified 65 cm below the snow surface at Lamar Bowl - Pilot Peak. The snowpit is included below for your perusal:

Stability tests conducted yesterday as well as snow observations did not revealed signs of instability with the most recent snow (moderate scores, but no propagation propensity and low shear energies -Q3). However, we never skied anything steeper than 30 degrees with a North or East aspect. After taking a look at the South and SE aspect snowpack (no weak basal structure found), and driven by the angelical Diurnal recrystallized snow, we farmed a SE slope with angles in the mid-thirties. Below the 6500 feet elevation the snow at South aspects turned into corn with supportable crust! What a day!

During the last three weeks I have ski and toured the Copper-Banner Summit, and Brundage-Sergeants ridge. Every snow pit at W/N/E aspect have consistently revealed the same WEAK structure; slab sitting in top of large cohesion-less facet crystals. When this layer is tested for fracture propagation, the results are consistent; fracture propagation potential is high. Feel free to entertain yourself with a video of a Propagation Saw test (PST) test performed at Brundage - Hidden Valley area last Sunday December 20th;

During our Christmas Day ski tour we observed MANY areas that slided a week ago. I have to admit that I was VERY surprised to see signs of avalanches in areas with slope angles in the low thirties! As expected all of the avalanches occurred at N, NE, E aspects. Below a picture of the popular "Almost Top of the World" slope. Notice the avalanche path next to the ski tracks (skier right, or looker left). And keep in mind that this was not the ONLY popular ski run that avalanched.

 It is IMPORTANT to remind backcountry skiers that ALL of these slide paths might become repeat offenders! The weak basal layer it is still present, and faceting continues unabated on the most recent low density snow deposited during the December 20/21st storm. As mentioned earlier on this blog posting, and documented in the snow pit included above, the "Mores Creek Summit" snowpack it is still experiencing significant temperature gradients not only at the top 20 cms but through its full thickness. Thus, we need to assume that at N, E, W aspects above 6500 feet the snowpack continues to change, and not for the BEST!

Once we get NEW snow at Mores Creek Summit (next week), I suggest winter recreationalists  to avoid the "familiarity" human factor, and to carefully evaluate and test every slope above 30 degrees before skiing it. Remember that most steep terrain at Mores Creek has severe terrain traps (trees and NASTY creek beds). These conditions are highly unusual conditions for our area, so it deserves conservative decision making!

Chago and Pedro