Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Possible
- Größe
- 3
If you've been following along, you're tired of hearing about persistent weak layers of faceted snow. So are we. This is the time of year when we are usually able to put this problem to bed but with such a dry season prior to Valentine's Day, the entire snowpack had become loose, weak, and faceted, especially near treeline and below on W-N-E aspects. Since February 14, several storms have built a well connected cohesive slab 2-3 feet thick on top of these faceted weak layers. These layers are very slow to heal but the likelihood of triggering an avalanche is decreasing. This is largely due to the strength of the over-riding slab, and how deeply buried the weak layers are. Shallower snowpack areas are the most dangerous, and likely trigger points are steep convexities, shallow rocky areas, and thin slab margins.
In my travels on Thursday I dug on a north aspect below treeline at 10,400'. In the photos below you can clearly see the weak, faceted snow underneath the over-riding slab. For the first time since Valentine's Day my extended column test produced no results, or ECTX. This indicates that avalanches are becoming more difficult to trigger but this is just one sample in one location. Knowing what's underneath, it's still a gamble, and I'm going to continue to hold my cards close.
The above photo illustrates a dense 4-1 finger hard slab over top of a fist hard, weak layer. The entire snowpack from the fist layer down is faceted. It's not a good looking set up.
For the first time since Valentine's Day, an extended column test produced no results (ECTX).
