Persistent Slabs
- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Possible
- Dimensione
- 1–2.5
The string of triggered slabs over the past week is a great demonstration that we have weak layers of snow buried in the upper portion of the snowpack across the board. Recent snowfall has built a hefty slab on the March 20 interface that is composed of slick crusts, facets, or some combination of these. This interface is now 2-3 feet deep. You are most likely to trigger this problem where a slab tapers in depth (below cliffs, in steep or rocky features with sparse trees, and in areas on steep slopes that have high continuity or are convex). These types of interfaces don't always heal quickly, especially with little relief from additional snowfall. When walking out the door today, remember that despite being later in the spring, you will be greeted with a mid-winter snowpack in the backcountry. This layer can be found in pits, and I was able to find it (and remotely trigger it) in the Snake River Range several days ago.
The Wyoming Range continues to have a thin and tricky snowpack with layers of weak snow near the ground and mid-pack. Triggering an avalanche on the above layer could step down and trigger a very large avalanche deeper in the snowpack.
Avalanches on steep slopes at low elevations will remain possible today and on any day with the possibility of a clearing. Cloud cover is particularly fickle in spring. Any direct sunshine for consistent periods of time will create instability on W-S-E aspects.
(3/27/2023)
Mosquito Creek Area remote triggered avalanche that failed on March 20th weak layer. 2-3' crown depth. D2 R3
Photo: Will Mook