At lower elevations, there was about 5-10 cm of new snow covering a supportable crust. Above 7200, surface snow conditions improved greatly with no perceptible buried crust interface and about 20 cm of new snow that has transformed overnight into diurnal recrystallized "near surface facet (NSF)" snow - what sometimes we accurately refer to "snow that has dried-out". This is accurate due to the fact that during the faceting process a volume of snow mass is lost to sublimation, as the precipitation snow is sublimated and deposited within the snowpack as facet crystals.
Above the new NSF we observed a widespread layer of surface hoar formed overnite.
|Surface hoar across my ski tips|
The first run of the morning was a surprise. Surface snow conditions were better than expected.
|Almost Top of The World - 1st run of the day|
|Whoop-Em-Up Headwaters Avalanche Path|
|Whoop-Em-Up Headwaters North aspect slope|
|Eric contemplating where to lay tracks next|
The persistent slab problem at MCS is found in specific areas such as shallow low elevation aspects (fortunately where we do not like to ski!) and at rocky and shallow northerly aspects above 7600. Those familiar with MCS recognize that these specific features are rare and easily recognizable. Besides, MCS skiers and sleds go for the readily available deep snowpack and rock-free areas to play in the snow.
As we skied down Lamar ridge the impact of solar radiation and warm temps became unmistakable - snow surfaces at east aspect slopes were saturated with liquid water. And it did not matter how good was the wax job in your ski, the ski difficulty level went rapidly up! 😰
It should be noted that we carefully selected a safe route down a south aspect slope with a shallower snowpack. At one point the "full" slope (under 30 degrees) fractured as I skied across it and energetically and unapologetically whumped as it collapsed few cms down in unison. A steeper slope would have avalanched. This instability is well known - a persistent slab at lower elevations. This instability was not related to either a wet loose or wet slab problem. It was simply the reactivation of an old persistent problem due to "snow creep" caused by warm temperatures creating traction at the slab and polycrystal/facet layer interface. This is the interface that Payette Avalanche Center continues to warn us about it, and that can be found at MCS.
Last Wednesday I went early in the morning with the intention of skiing the northwesterly aspect slopes of Mack's Creek, below Bogus Basin "Triangle" ski area and to do snow research work for the Avalanche and Snow Physics class I am supporting Hans Peter Marshall teach at Boise State Unversity.
|North-westerly slopes above Mack's Creek near Bogus Basin|
|Top of Bogus Basin from Mack's Creek NW aspect slopes.|
|Cold snow at Mack's Creek|
Instead of skiing, I identified a side-country slope near the Bogus Basin access gate for Mores Mountain, where I spent part of the morning doing snow research.
|During snow, research scientists record snow layer depths normal to the snow surface, not "plumb"!|
|Very rare event - Two Denoth instruments in the same pit! Thre are very few snow capacitance instruments in the world (Expensive).|
|Using capacitance plates to measure the snow resistance to an electromagnetic field (a physical property called permittivity).|
|Capacitance measurements versus snow density (gm/cc)|
A final topic to write about, and I must declare that I am uncertain how to communicate to the timber sled users. Mores Creek summit coexistence between snowmobilers and backcountry riders is something I feel proud about it. We depend on each other. I feel safer with the presence of snowmobilers. I KNOW they are my HELPLINE if an emergency arises! Also, the snowmobile community has gone out of the way NOT to impact the area accessed by backcountry riders. I respect them greatly for that.
Last year I started to observe timber-sleds accessing terrain used by skiers. I considered these occasional incidents as part of the learning process for these new "timber-sled" users. Besides, I always espoused the belief that MCS is a large area, and the perception of crowding is the result of lack of imagination of where to go skiing. However, I was deeply concerned about the unsafe manner timber sleds traveled through steep terrain - cutting sideways through significant distances. This is annoying to some of us that care about the aesthetics of ski lines since large tracks of ski terrain get unnecessarily impacted. The truth is that this season I had seen many skiers doing the same with their uphill tracks!
This past Saturday as I skied down to the I-21, it was hard not to notice the significant timber-sled side-hilling across the terrain used by skiers next to Almost-Top-of-the-World (see pictures below).
|Timber-sleds tracks across slopes next to "Almost-top-of-the-World.|
|Timber-sleds tracks across slopes|