Persistent Slabs
- Alta montaña
- Límite del bosque
- Bajo el límite del bosque
- Probabilidad
- Likely
- Tamaño
- 2–3
The recent storm deposited 2-4' of snow (2.5-3.1" SWE) across this zone. This snow fell on an exceptionally weak layer of snow made up of crusts, facets, or a combination of the two. This combination produced a widespread natural avalanche cycle, with slides observed on all aspects and at all elevations. You'll find this combination of a thick slab overlying a reactive weak layer almost everywhere you go today. The slab of new snow is thick enough that the wind doesn't need to have done any work to build a slab—avalanches are possible in both sheltered and wind-affected terrain.
Thanks to this ugly weak layer + slab combination, the possibility of remotely triggering avalanches is very real. A collapse on mellow terrain at the valley floor can quickly travel long distances and release avalanches on steeper slopes far above. Pay close attention to the terrain around you and above you. Remember that there are other people out in the mountains and that impacting them and being impacted by them is possible.
ADDITIONAL DISCUSSION: An uptick in wind speeds was recorded at some weather stations overnight and fresh slabs are likely forming as I write this. The wind will continue to transport snow and build slabs until things calm this afternoon. These thin, fresh slabs may be particularly sensitive today, but they will be relatively small. Most importantly, they are adding load to the weak snow underneath and can act as triggers for the slabs described above.