Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 1–2
Faceted weak layers can be found on most aspects above 8,000 feet, and they vary significantly across the landscape. This variability requires an extra margin of safety; now is not the time to let your guard down and become complacent. Up there, backcountry travelers could trigger persistent slab avalanches failing on these weak layers with depths ranging from one to three feet. Large triggers, such as snowmobiles, are more likely to initiate one of these deadly avalanches. Don’t let yourself be lulled into thinking a slope is safe if it has been previously ridden or skied. Below 8,000 feet, any avalanche activity will likely be less than 18 inches deep.