Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 4
The most prevalent and most deadly avalanche problem is both soft and hard slabs of snow failing on persistent weak layers near the ground. These weak layers of faceted, sugary snow exist at all elevations on nearly all slopes except ones facing south and southwest; however, I don't totally trust those south facing slopes just yet. Because these weak layers are stressed and ready to fracture, many slopes are waiting to avalanche as soon as someone rides on or even near them
Snow and wind since mid January have created a thick cohesive slab on top of these weak layers. At upper elevation slopes loaded by winds, this slab is very hard and 4-5 feet thick. At lower elevations this slab is softer and 2-3 feet thick.
Here's the tricky part - with such a thick and dense slab on top of these weak layers in many places, it may let several people ride a slope before producing an avalanche. The first person or the tenth person may be the one who triggers it. The main point is that tracks on a slope DO NOT mean it is stable.