Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2.5
Persistent slab avalanches are possible today in the Southern Wallowas and Blue mountains. A persistent slab avalanche occurred a few days ago in the Southern Wallowas up Little Eagle Creek. This avalanche was triggered by a snow mobile rider and was large enough to bury, injure, or kill a person. The weak layer consisted of buried surface hoar. We continue to see buried surface hoar in all of our snowpits throughout the mountains of Northeast Oregon. These layers of buried surface hoar continue to be reactive in the stability tests we have been performing.Extended Column Tests and Compression test results are showing columns are failing, accompanied with propagation, consistently. Compression test shears at the weak layer have been unusually clean and planar. These poor stability test scores coupled with the observance of recent human triggered avalanches in the Southern Wallowas indicate compromised snowpack stability. This buried persistent weak layer could be tested today especially in the Blue mountains where they received 1.1" of water weight onto the snowpack in the last 24 hours. Evaluate carefully any steep slope over 30 degrees you are considering today. If you see or hear signs of recent avalanches, shooting cracks projecting out from skis or feet, or whumpfing while traveling, these are red flag warning signs that the snow is unstable and that you should seek your fun on low angle slopes less than 30 degrees in steepness.
(1/25/2023)
Snowmobile triggered slab avalanche approximately 3' deep on north aspect at 7400'. Weak layer was buried surface hoar.
