Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 1.5–2.5
In wind-loaded areas, avalanches could be dangerously large and may break widely across terrain features or be triggered from a distance. Look for recent avalanches, textured snow, and thick, pillow-like drifts that highlight slopes of concern. Keep your distance from these features and stay well clear of cornices.
Winds recently overloaded weak layers in our snowpack, and many natural and triggered avalanches have been reported over the past few days. Observers continue to report collapses, long cracks, and propagating test results. An NWAC forecaster observed a widely propagating avalanche on Rock Mountain that likely occurred naturally on 2/27. Warm temperatures and sunshine could prolong instability and, while less likely, may also increase the likelihood of persistent slabs on steep, sheltered sunny slopes. These weak layers (facets and surface hoar) adjacent to crusts are 1.5 feet deep and widespread on most aspects and elevations.
(2/28/2026)
A wide avalanche (D2) on the southeast aspect of the South Peak of Rock Mtn. On the far right, broken cornices and a portion of a crown on the east face. E-S, 5,500ft-6,700ft
Photo: Josh Hirshberg