Observation: Public

Observation Details

Signs of Unstable Snow

Observations

Recent reports of unstable conditions encouraged me to travel towards Hidden Lake Lookout via the winter (ridge) access trail, avoiding all avalanche terrain upon ascent. We continued along sub-ridges in the vicinity of the summer trail above treeline to the saddle north of the lookout before descending. We returned on a route closer to the summer trail, although choosing the thicker trees for the steep part of the descent before reaching the major avalanche path along the East Fork of Sibley Creek.

Below treeline there was a slightly soft edgeable crust with about 2" of snow on top, much more agreeable conditions for both skinning up and descending than last week. By treeline at about 5400ft snow cover was 4-6" over the crust, but becoming more variable and wind affected. Above treeline we found many windswept patches scoured down to the 1/13 crust. We also found deposits of snow ranging up to a foot deep. Constant hand pits found inconsistent surface layers overlying the 1/13 crust. In some areas there was 4" of low density snow over it, but thicker areas had up to 6" of P wind slab with softer 1mm subtly faceted snow beneath it, overlying the crust. Hard planar shears sometimes occurred between the slab and softer layer beneath. Even in those areas, like all others, we found that the snow was well bonded to the crust. Despite the reassuring results from constant hand pits, we chose to avoid any steep slopes in obviously wind loaded areas, so did not see if any weaker interfaces were present there.

We did not see any new avalanches. However, we saw many signs of large old avalanches (up to D2.5) from the atmospheric river event (around 1/13), including numerous glide cracks and glide avalanches on south aspects. There were also large slab avalanches above treeline on west facing slopes, and smaller ones on gentler unsuspecting slopes in near treeline terrain.