Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2
Buried weak layers of facets and depth hoar sit near the base of the snowpack. These layers were responsible for the last slab avalanches reported in this zone (see photo) and remain our greatest concern. Triggering an avalanche on one of these layers is unlikely but the resulting slide will be massive.
Here are some considerations to help you reduce your risk:
- Recent wind-loading: Slopes with stiff or hard layers somewhere above the weak layer are more suspect than slopes where you can easily get your arm, ski pole, or sled down to or near the ground.
- Slope angle: Avalanches are most likely in "prime time" avalanche terrain, slopes around 35-45 degrees in steepness. However, remember that persistent slab avalanches can be triggered remotely–from gentler terrain below or to the sides of steeper slopes.
- Aspect: Last week’s avalanche activity was focused on slopes where the sun had formed crusts.
Additional Discussion:It’s been windier in this zone than the relative calm experienced to the north. Be on the lookout for small wind slabs in exposed terrain particularly in areas with greater recent snowfall like Dollarhide Summit and the Soldiers. If the clouds hold off until later than forecast, loose snow avalanches are a possibility again this afternoon. These slides are most likely on sheltered SE-S-SW-W facing slopes while they directly face the sun.