Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2
Our primary concern today is the potential for triggering an avalanche within the top 1-3 feet of storm snow that fell earlier this week. Small avalanches will be possible within the recent storm snow in areas that have been affected by wind. Larger avalanches will be possible at the interface of recent storm snow and old wind-affected bed surfaces. In isolated locations, there is a weak layer of surface hoar below the recent storm snow creating a more sensitive instability.
Avalanche likelihood today will depend on whether or not this weak layer of surface hoar is present under recent snow. This layer has recently been found in colder glacier valleys and Northerly aspects above 3000 feet. Surface hoar will be found just above old wind-damaged snow at depths between 1 and 3 feet. This situation is concerning because it will be difficult to assess. Spotty distribution and deep burial of the surface hoar in areas will make it difficult to locate. Additionally, this weak layer is becoming stubborn so signs of instability may not be apparent in areas where an avalanche is likely to be triggered. Careful assessment and terrain progression is advised especially when entering a new drainage/slope.
Areas lacking buried surface hoar have shown good stability with conditions improving over the last few days. The general trend is increasing stability but a cautious mindset is prudent due to pockets of less stable snow that could surprise users today.