Persistent Slabs
- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Possible
- Dimensione
- 2–3
It has been several days since the last reported Persistent slab avalanche and as time goes on without a significant loading event these avalanches are becoming harder to trigger. Nevertheless, recent field observations continue to show signs of unstable snow including collapsing, shooting cracks, and propagating test results. While large triggers such as a small wind slab avalanche or a cornice fall may be required to initiate a persistent slab avalanche today, shallow trigger points such as buried rocks or small trees are areas of concern for the backcountry traveler. These are areas where the weight of a skier/snowboarder may be enough to initiate slab failure. While becoming less sensitive over time, avalanches breaking on these lower weak layers have the potential to be large and destructive.
Persistent Slab problems challenge our patience, and managing this problem requires extensive evaluation and deliberate terrain choice. Don’t be afraid to investigate the lower reaches of the snowpack to see if old snow is present in the areas you wish to travel. This may mean digging all the way to the ground if you suspect old snow is present. Remember that persistent slab avalanches often propagate across and beyond terrain features that would otherwise confine surface instabilities such as wind or storm slab. Persistent slab avalanches can be triggered from lower angle terrain, the bottom of a slope, and in some cases, remotely triggered from adjacent terrain. Give yourself a wide safety margin, be wary of hazards that may reside above you, and use terrain choice to limit your exposure.
