Persistent Slabs
- Hochgebirge
- Waldgrenze
- Unterhalb der Waldgrenze
- Wahrscheinlichkeit
- Possible
- Größe
- 2–3
No new persistent slab avalanches have been reported in the last few days. Obvious signs of instability, like collapses, whumpfs, and shooting cracks, have become less common in some places, however, weak snow still exists at the bottom of the snowpack. Observations and snowpit data like this one from Elephant's Hump yesterday, where an entire low-angle slope collapsed, continue to indicate that the snowpack remains unstable. This variability makes it much harder to assess whether or not a slope will avalanche. The variability even extends to a single slope. Traveling on some parts of a slope might not cause it to fail, while touching another part of it could rip the entire slope out, including the previous tracks.
Large human-triggered persistent slab avalanches 1.5 to 4+ feet deep are still possible. They could break much wider than expected. NW-N-NE aspects above about 8,000' where the Dec 1 persistent weak layer remains weakest are the most suspect, but other areas may also hold some isolated lingering instability.
This time represents a challenge for all backcountry users; it is the time when we start to get impatient and complacent. We want to step out into more complicated terrain despite the uncertainty. Sometimes we get lucky, and nothing happens, but if someone triggers an avalanche today, it will be big and have serious consequences. Choosing to travel in avalanche terrain means accepting the uncertainty, risk, and potential consequences associated with this persistent slab problem. Choosing to slay the pow on lower-angle terrain not exposed to steeper terrain, represents one way to have fun and reduce exposure to the persistent slab problem.
(12/7/2022)
One of two wide propagating natural avalanches on this slope. Likely occurred on Dec 3 or 4. N aspect terrain around 7,700'. Deer Creek drainage near Mt. Watson, CA.
