Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 2
The storm early last week added more load to our well-established persistent weak layer that is now buried around 1-2 feet deep in this zone. The highest concentration of avalanches occurred in the western portion of this zone (see observation from the Soldiers) where more snow fell, but natural slides were also observed in the Wood River Valley, in Bassett Gulch on the backside of Baldy, and in the Warm Springs drainage.
On Sunday, an experienced skier north of this zone remotely triggered a large avalanche that failed on a steeper slope adjacent to where he was skiing. He reported hearing wood breaking as the avalanche descended the slope. I looked at this slide and a few others yesterday, watch a video recapping what I saw here: Butterfield Avalanche. I was in the Gladiator Creek drainage on Sunday, investigating a large natural avalanche (photo at right) that appeared to have released within the past two days. You can watch a video describing what I found and why it is important here: Gladiator Creek Avalanche. The snowpack in both of these areas is similar to the snowpack found in this zone.
There are two key factors that point to this instability being especially long-lasting and unpredictable: 1) the buried weak layer is especially bad, and 2) this weak layer has been very slowly loaded over the past three weeks. Recent natural and human-triggered avalanches confirm this fact. We urge backcountry skiers and riders to continue to choose low angle slopes and to pay extra attention to the terrain they're "connected" to. Remotely triggering an avalanche from below, above, and to the sides of steep slopes remains a very real possibility.
(1/10/2021) Bed surface and debris of large natural avalanche in upper Gladiator Creek