Persistent Slabs
- Alta quota
- Limite del bosco
- Sotto il limite del bosco
- Probabilità
- Likely
- Dimensione
- 1.5–2.5
Recent storm snow was deposited on a snowpack with multiple weak layers. Our storm snow avalanche problem has transitioned to a persistent slab avalanche problem. Weak near surface facets formed during the multi-week dry period since the Thanksgiving holiday on northerly aspects at all elevations. This weak layer now has up to 1 to 3 feet of new dense storm snow on top of it. This weak sugary snow will be much less dense than the recent storm snow, potentially leading to persistent slab avalanches occurring today.
In more isolated areas in the southern and eastern portions of the forecast region, basal facets on the ground could be reactivated by the recent storm snow. These basal facets exist on NW-N-NE aspects above around 8000-8500', where a shallow and weaker snowpack structure formed.
Uncertainty exists about this avalanche problem. Very limited information and observations have been collected since the start of the storm cycle. These weak layers are highly variable throughout our forecast area and will gain strength at different rates. Recent avalanches, snowpack cracking, collapsing, or whumpfing sounds will indicate that this avalanche problem is reactive in your area. These avalanches could be large, with wide propagation, and could be remotely triggered from a distance away. Don't let this sunny powder day lull you into complacency, large and dangerous avalanches could occur.
