Quick report
- Red Flags
- Recent Avalanches, Heavy Snowfall, Wind Loading, Cracking, Collapsing, Poor Snowpack Structure
We originally intended on going to Mineral Fork. Right when leaving the car we intentionally triggered a small avalanche right adjacent to the roadside. It was possible this was a drifted slope as winds did work their way down low into mid Big Cottonwood Canyon. (video below). We later decided to abandon plans for traveling into Mineral as our skin track took us below large, west-facing slopes above us, with serious consequences if we had triggered an avalanche. There was a 60 cm dense storm slab on top of weak, saturated snow down near the ground (HS was 75-90 cms). We were getting collapses - but not propagating - but the prospect of triggering deep avalanches in unforgiving terrain made us easily decide to change plans for the day.
We decided to head up canyon to the Brighton backcountry, and traveled along the ridge along Clayton Peak. We were able to look at terrain between 9800' to 10,700' on slopes facing northeast through southeast. Much of this terrain had apparently avalanched naturally, most likely during the day on Thursday. The paths had filled in with shallow wind slabs, and in wind-protected terrain, with 10-30 cms of soft, low-density storm snow that fell late in the storm. We kicked a few cornices, but at most could get a few shallow pockets of wind-drifted snow or loose sluffs.
We did not get a good idea of how sensitive the storm snow and fresh wind drifts were as much of this terrain had already avalanched. Given the large water and snow amounts (45" snow and 4" water at Brighton since Wednesday) it seems likely slopes that haven't already avalanched are still suspect. We felt the minimal results we were getting was because the slopes we had looked at had already avalanched.
Video of avalanche adjacent to the road. Test slopes often tell you all you need to know!
While heading up Big Cottonwood Canyon we noticed that El Rollo, a steep roll-over in the Meadow Chutes, had also naturally avalanched.
Hazard rating is difficult. Most likely was Considerable where we were traveling, but this was because much of the upper elevation terrain we had looked at had already avalanched. We also did not like the structure of the snowpack at the low elevations (~7000) with heavy, dense snow on top of saturated snow down near the ground.
Snowpack
- Instability Comment
- <p>Strong winds drifted snow at the mid and upper elevations. We were able to pull out a few shallow drifts off of northeast through southeast aspects below Clayton Peak.</p> <p>Storm snow should continue to settle out, but the layer of low-density stellars that fell early on Wednesday, are are now buried by 30-60 cms of storm snow remains a concern.</p> <p>At 7200' the pre-existing snowpack prior to the Thursday/Friday storm was saturated, with apparent rain to that elevation on Thursday. We were able to ski cut a few steep test slopes, and the storm snow would gouge down into the saturated snow near the ground. Am not expecting this to remain a concern for very long, but at low elevations storm snow on very steep aspects could produce very deep avalanches.</p>
Dense snow in wind-affected terrain, with lower-density snow that fell overnight Thursday in wind-sheltered areas.