Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Likely
- Größe
- 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" as many slopes finally passed their breaking point.
We're now faced with a particularly dangerous and long-lasting instability, especially in the western portion of this zone where more recent snow has fallen. The weak layer is buried around 1-2' 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). A professional observer in the East Fork of Baker Creek (far northern end of this zone) reported dramatic collapses and recent avalanches that may have been human-triggered.
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—especially in the Soldiers. 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.
(1/15/2021) A Soldier Mountain Cat Ski guide remotely-triggered this avalanche on January 15th near Peak 2 in the Soldiers. It was triggered from a low angle slope nearby and likely ran on the December facet layer. Photo courtesy of Soldier Cat Ski.