Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Possible
- Größe
- 2–3
Weak layers - surface hoar, faceted grains, and a faceted crust - two to three feet deep are the culprit of lingering instability in the upper snowpack. Snowpack tests on slopes near treeline down to about 5,000 feet continue to produce ongoing failures in these weak grains. Well-preserved and upright surface hoar is found on north to east-facing slopes, while southeast through south to west-facing slopes harbor a breakable crust with facets looming above and below. While deeper weak grains are showing evidence of strengthening, the ability to affect weaker snow and trigger a slide appears directly influenced by overlying slab depth.
(2/16/2025)
Surface hoar feathers are still 10 to 12 mm in size below a stiffening slab. While becoming harder to impact, they still produce propagating failures in tests. Selkirk Mountains. February 16, 2025.
Photo: Chris Bilbrey