Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Likely
- Größe
- 2
The storm early last week added more load to our well-established persistent weak layer that is now buried around 1.5-2 feet deep in this zone. Many natural avalanches occurred as a result of the storm, with the highest concentrations of observed slides in the Baker Creek (photo, photo) and Pole Creek (observation) drainages.
Last Tuesday, Wednesday, and Thursday, there were small remotely-triggered avalanches in this zone each day. Observers on Galena Summit yesterday continue to report collapsing and cracking of the snowpack in addition to poor test scores. Long-time experienced sledders in Baker Creek yesterday could feel their tracks punching into the weak layer and stuck to gentle terrain.
There are two key factors that point to this instability being especially long-lasting and unpredictable: 1) the buried weak layer is especially bad, and 2) this weak layer has been very slowly loaded over the past three weeks. As time goes by and the obvious signs of instability diminish, it requires more and more discipline to choose appropriate terrain—read more on that in the Forecast Discussion below. We urge backcountry skiers and riders to continue to choose low angle slopes and to pay extra attention to the terrain they're "connected" to. Remotely triggering an avalanche from below, above, and to the sides of steep slopes remains a very real possibility.
(1/6/21) Sun Valley Heli Ski staff reported dozens of large natural avalanches in the western Smoky Mtns. They remotely released 3 separate 3-6 ft deep avalanches when landing the aircraft in standard, safe landing zones. The slides released up to a quarter-mile away from the helicopter.
Photo: Sun Valley Heli Ski