Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3
The snowpack in this area grew from toddler-sized to NBA basketball superstar heights in the past two weeks. The persistent weak layers (facets, surface hoar, and crust+facet combinations) below the recent storm snow and near the ground are widespread and are now 4-7 feet deep. This is a bit of a double-edged sword. While you are not likely to trigger one of these deeper slabs, the consequences of being caught in one would be severe.
Dealing with deeply buried persistent weak layers challenges even the most experienced backcountry users. The snowpack probably won't provide you with signs of instability before it fails. One minute you are riding powder, and the next minute you are cascading down a slope with the entire season’s snowpack.
Unfortunately, the only way to effectively manage this problem is avoidance; stay out of the terrain where the problem exists. If you're willing to dance with the proverbial dragon, steer clear of slopes where you see rocks poking through the snow. The odds of triggering a huge avalanche increases in shallow, rocky areas that allow you to impact the weak layer as well as in wind-loaded terrain. In the thinner areas, you may also be able to trigger 1-3 foot thick slabs on weak layers closer to the surface (see Galena Summit & Eastern Mtns forecast).
ADDITIONAL DISCUSSIONLast night's snowfall and wind may have formed thin, isolated wind slabs near ridgelines in exposed terrain. While these slides should not be large enough to bury people on their own, there's a chance a small avalanche could trigger a larger, deeper slab as it travels downslope.