Deep Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Unlikely
- Size
- 2–3
Recent Avalanches: On Friday, a small wind slab was triggered by a snowmachiner at 2,500' on a southeast facing slope in the Snug area. Natural avalanches probably occurred during the wind event, but we haven't been there or received reports.
It has been almost 3 weeks since a large avalanche has occurred on the weak snow that formed in Decemberin the Seward area. There are a few reasons why this is still our main concern despite the lack of avalanches and low likelihood.
- Poor structure still exists in thin spots in the snowpack. A large slab is sitting on very weak snow in places. This layer has gained strength over time, but these types of layers are very hard to fully trust and the consequences could be devestating if the unlikely avalanche occurs.
- The large avalanches on the north side of the Girdwood area tell us that large avalanches could still occur in the right thin spot with the right load. That side of the Girdwood valley has a different snowpack than the south side of the valley and Seward, but we think there are thin spots in Seward in the upper elevations in wind scoured places that have similar structure to where those avalanches occurred.
We think it is unlikely that a person could trigger one of these avalanches, but there is always some uncertainty with this type of problem. Some things you can do to reduce your exposure and vulnerability include checking safety gear at the parking lot, choosing safe, low angle up routes, avoid riding close to rocks, and travel one at a time in steep terrain while watching partners closely.
