Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Possible
- Größe
- 3
The three human-triggered avalanches from Thursday all ran on the persistent weak layer (PWL) of weak, faceted snow that is found at the base of our 2-3' deep snowpack on mid and upper elevation slopes facing west through north and east, including upper-elevation southeast. As this weak layer slowly adjusts to the weight of the storm snow from Tuesday, you may get fewer clues - such as cracking and collapsing - about this instability and tracks on a slope may give you a false sense of stability.
If you choose to venture onto slopes where this PWL exists, you will have to first dig down and look for the structure of strong (harder/firmer) snow on top of weak (softer/looser) snow (see image below). If you see this structure, it is possible you will trigger an avalanche up to 2' deep and over 100' wide.
Photo of the crown of the avalanche on Scott's Bowl that failed on the PWL: