Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Possible
- Größe
- 1.5–2.5
What and where is it? Slopes where 1.5-2.5 foot thick slabs lie above persistent weak layers—strong over weak layering—are suspect. You'll find this setup on many upper elevation slopes and on shadier slopes (W-NW-N-NE-E aspects) at the higher end of middle elevations.
How can you recognize it? On shadier aspects, you can easily feel the old crusts and sugary facets with your hands, ski pole, or snowmobile track. On sunnier aspects, the weak layers present as a series of crusts and facets and are not as obvious. Watch the great video below/to the right and read the Forecast Discussion for some tips on how to evaluate the slab.
How can you manage it? Sadly, the only surefire option is to avoid avalanche terrain where denser slabs rest above the weak facets and crusts. Short of that, you can reduce your risk by avoiding large avalanche paths and those with ugly consequences if you are caught in a slide.
Remember that Persistent Slab avalanches can break wider and higher on slopes (above you) than you might expect. Tracks on a slope do not guarantee the slope is safe—several skiers or riders may descend a slope only to have the next person trigger an avalanche.