Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 1
Avalanche season is on our doorstep. The shady upper elevation slopes harbor enough old snow to be a problem. The old snow has weakened into a mix of sugary facets and thin crusts. As the first few inches of snow add up today, new snow sluffs will be easy to trigger, running on the crusts or the weak facets. These loose snow sluffs will run further than expected in steep terrain.
If you're in upper elevation terrain that gets more than about 6 inches of snow on top of the old, weak snow, expect to trigger very sensitive shallow slabs of snow, especially in any wind drifted areas. These slides will be breaking on the persistent weak layer of faceted snow, and can be triggered from a distance. While shallow, again, they could run much further than expected.
Here is a great photo by Greg Gagne of the old snow that was on the ground yesterday, in the Cottonwoods. It is similar to what you will find on upper elevation, shady slopes in the Provo area mountains.