Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3
Recent Avalanches: We continue to see glide avalanches release from Girdwood to Seward. The last known avalanches that weren't glide-related happened during the widespread cycle following the Thanksgiving storm, over two weeks ago.
There are multiple layers of weak snow buried anywhere from 1 to 3' deep or possibly deeper on some slopes. They can be lumped into two groups:
1. Weak, faceted snow up to a foot deep. This has formed during the current cold snap, and was buried by yesterday's northwesterly winds. This will be more concerning as you gain elevation, and will be most concerning in previously wind-loaded terrain.
2. Three different layers of buried surface hoar. These were buried during three separate storm events in November. The last known avalanche on any of these weak layers was over two weeks ago, which may indicate these layers are gaining strength, or it could simply be a result of decreased traffic since the last avalanche cycle. It's most likely a combination of the two, and we suspect a person may still be able to trigger an avalanche on one of these layers on isolated slopes above treeline.
Group 1 will be easier to evaluate than Group 2, but you will not always get clear feedback even when conditions are dangerous. As always, pay close attention to warning signs like shooting cracks, collapsing, and fresh avalanche activity as indicators of unstable conditions. If you are venturing into steep terrain, be sure to avoid slopes that have been wind-loaded over the past few days. It is also important to be mindful of the higher uncertainty associated with evaluating layers of buried surface hoar, and consider avoiding slopes with terrain traps like cliffs, trees, or gullies in the runout zones.
(12/13/2025)
Shooting crack on a test slope at the top of a gully feature on Cornbiscuit. This is a clear sign of unstable snow.
Photo: Kip Sprout
