Deep Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–3
Avalanches that run on deeply buried weak layers could be 3-4ft or deeper, and can propagate widely across the slope. You won't get signs of instability before triggering one, as the layer is too deep. Your best bet is to remain aware of the terrain around you, staying out of complex alpine terrain and off of steep, unsupported, or wind-loaded slopes.
The weak snowpack structure has been slow to gain strength. You can find a thin layer of softer facets over a hard crust, about 3 .5-4.5 ft below the surface. This layering (and the likelihood of triggering avalanches) is most pronounced at upper elevations (above 5,800ft) and further east in the zone. On Tuesday, a skier was buried in a large avalanche that likely ran on the early February facet/crust layer on Jim Hill.
(3/5/2024)
Large deep slab off the W summit slopes of Jim Hill. NW at 6,500ft.
Photo: Nate Hough-Snee