Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–3
Several weak layers exist within our snowpack. Surface hoar, near-surface facets, density changes caused by wind and temperature fluctuations, grauple, sun and rain crusts...you name them, we have them. Not all of these layers are found in all areas, several of them may be found in one area. ALL of them should give you reason for concern and a healthy suspicion of the snowpack.
Yesterday's snow formed our most recent persistent slab about 6 inches deep that was sensitive enough to tigger an avalanche on skis: it easily popigated out about 150 feet from our skis on the ridge touring out to Sgts Mtn Saturday and ran about 200 vertical feet, then with one stomp I was able to trigger the North aspect about 200 feet wide by 200 vertical veet. Previously buried surface hoar near 75cm/30in is resting just above the rain crust that was buried on 1/26. This layer is incredibly reactive in some areas and not present in others which is a trend that add uncertanty. Steep slopes in wind-protected or wind-loaded, shady terrain is where you are most likely to find it. This is the layer that has been producing human triggered avalanches for almost 2 weeks.
The most repeated message from Avalanche Centers across the Western US right now is "avoid steep slopes", with human triggered avalanches and avalanche fatalities continuing to stack up, pay attention to your slope angles and keep an eye on your partners.