Deep Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3.5
Storm and wind slabs are likely to have grown to 2-3 meters thick. These slabs overlay early season snow that has metamorphosed into depth hoar. Some slopes may have already released during our MLK storm week, while others may be on the verge of releasing. Near and above treeline, avoid all wind loaded slopes, pillowed slopes and cornices, as well as terrain connected to slopes with these features above. Steep convex rollovers should be avoided.
We had large and very large persistent slab avalanches release during our New Year’s Storm cycle. Slabs that have not yet avalanched are now six feet (2 meters) thick or more.
"Deep Persistent Slabs are very difficult to predict and manage. They are low-probability high-consequence events. If you are caught in one, you are unlikely to survive. Often the only evidence of the problem arrives too late as a large, deadly, and unexpected avalanche. The only real effective risk management strategy is to avoid areas where you suspect a Deep Persistent Slab. They are most commonly triggered from shallow spots in the snowpack [usually located at the margins of the slab or slope]. Avoiding these areas is one way to reduce risk. Give yourself a wide safety buffer to handle the uncertainty, potentially for the remainder of the season." - CAIC
