Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Unlikely
- Size
- 1.5–2
Your odds of triggering a large, dense slab avalanche are low but not zero. Avalanches are easier to trigger in thin spots at the edges of slabs and wind-features. Watch for these trigger points on the northern half of the compass, where the wind frequently blows, and the snowpack depth is variable. Many shady slopes in rocky alpine cirques fit that description. Some visual clues to identify suspect slopes:
- Stiff or textured surfaces and wind-pillows, evidence the wind has moved snow
- Rocks sticking out of the snow, either near or well below ridgelines
- Terrain where some part of the slope is at least 35 degrees in steepness
If you do trigger an avalanche, you probably won't observe obvious signs of instability like snowpack collapsing or cracking beforehand. Any triggered avalanches have the potential to break above you.
Additional Discussion: Last night's snowfall and wind may have formed isolated, thin wind slabs near ridgetops and in alpine terrain, especially in the southern reaches of this zone. Although the fresh slabs should be small, they could be easy to trigger and may release naturally in windy locations. The small slides could entrain weak, faceted snow as they move downhill, becoming large enough to knock you off your feet or sled and carry you where you don't want to go.