Persistent Slabs
- Alta montaña
- Límite del bosque
- Bajo el límite del bosque
- Probabilidad
- Likely
- Tamaño
- 2
The slow loading of the December facet layer has produced a well-established persistent slab problem across the entire forecast area. Each storm has produced a new round of avalanche activity, but last week's storm caused things to "go off" in this zone as many slopes finally passed their breaking point.
We're now faced with a particularly dangerous and long-lasting instability. The weak layer is buried around 2' deep on almost every slope. Often there is a high degree of uncertainty surrounding persistent slab problems. Now is not one of those times. On Friday, Soldier Mountain Cat Ski guides remotely-triggered an avalanche in the Soldiers. Yesterday on Galena Summit, skiers remotely triggered a 2+' deep avalanche from low angle terrain (photo below/right, more details). Observers from across the zone continue to report dramatic collapsing of the snowpack. A rider in Pole Creek yesterday summed it up: "There was no need for a test pit, it was very obviously unstable."
Conditions remain dangerous, and it's likely you'd trigger a large avalanche on most steep slopes. The best—and often only—way to manage the persistent slab problem is by sticking to lower-angled terrain. Given the possibility of remote-triggering, you'll also want to avoid being below steep slopes.
WIND SLABS: Strong winds last week ravaged the snowpack, and we've had several more rounds of wind since the storm ended. Although wind slabs are becoming less reactive to the weight of a skier or rider, wind-loaded slopes will have more stress on the buried weak layer making them especially dangerous. If you do trigger a lingering wind slab, it could "step down", failing on layers deeper in the snowpack and becoming much larger than the initial avalanche.
(1/16/2021) Avalanche on Galena Summit that was triggered remotely from 250' away on Saturday. The avalanche broke over 2' deep in mid-elevation terrain.