Sunday, March 5, 2017

Bogus Sidecountry - South Fork of Macks Creek

It has been a while since I have skied Bogus Basin side country. This past Wednesday I accessed the side country terrain below Paradise cat track (or more commonly known as the Triangle) through Mores Mountain backcountry gate. Technically this terrain can be considered part of South Fork of Macks Creek, to the east of Mores Mountain. It should be noted that the snow coverage was terrific. I arrived at the gate past 4 PM, thus I was limited how much I could ski tour. The skiing was fun with 20-25 cms of soft snow in a burly crust. It was important to be gentle and keep the speed to avoid the crust underneath the skis.

Saturday, I returned to the South Fork of Macks Creek. This time I had more time to do five laps. Just 3 meters after leaving the Mores Mountain gate, a wind affected roll over provided a reminder of the touchy nature of wind slabs. Fortunately, I was heading to terrain that was not impacted by snow.

Shallow Windslab
When skiing down into Macks creek to access the terrain below Bogus's Paradise cat track it is vital to use good navigation skills and prudence. The bottom gully is steep, but it provides safe crossings without exposing a party to terrain traps.
Mack's Creek Steep Gully - a  classic terrain trap!
After crossing the south fork of Mack's Creek the rest piece of cake. Build an efficient uphill track that will facilitate skiing the three open meadows. Be mindful that the bottom of the ski runs steepen significantly, and put you right into unforgiving avalanche terrain traps. Do not allow to be lured into them!

Skiing this area is very scenic, and because of its lower elevation and nearby topography is protected from winds. In other words, pow is well preserved! Below several pictures from yesterday tour.

One of my sons likes to call this area Shangri-la. And yesterday I was reminded why!

A quick look at the snowpit provided insights about the snowpack development during the last few weeks. Often, when I am alone instead of transcribing data I take pictures of important aspects. Below an example.

Notice on the first two pictures the hardness test results marked on the side wall of the pit. The snowpack was 235 cm deep, but I only excavated until the early February thick rain crust layer 67 cms below the snow surface. The last two pictures document the angle and aspect of the snowpit; 36 degrees in steepness and 3-4 degrees True North (no declination).

Stability test are summarized next;
  • ECTP5 at 45 cm, between two crusts.
  • CTEQ1(SP) at 25 cms, new snow.
  • CTMQ1(SC) at 45 cms, facets sandwiched between two crusts.
  • PST20/100(SF).
Basically, these tests suggest the presence of propagation potential at 45 cm. The question is where in the terrain this failure can become easy to trigger. Although the Extended Column failed as a sudden collapse, the Propagation Saw test was arrested at 40 cm when the slab fractured. It is possible that the slab is not yet cohesive enough to sustain propagation. But warm temps yesterday might have provided the necessary ingredient to form isolated slabs that could surprise us.
Evidence od snowpack warming
The new snow instability is present at ridgetops and/or wind affected areas, where a slab is formed by wind and make it possible to propagate a failure, as seen in the video provided early in the post.

For about an hour fog moved in. This was an opportunity to enjoy magical moments with hidden treeed gullies. Very fun skiing indeed.

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