Persistent Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Possible
- Size
- 2–2.5
You can trigger a dangerous avalanche where southwest winds are drifting recent snow into cohesive slabs above weaker layers below. The most dangerous slopes face northerly or easterly directions. Avalanches which you trigger in the upper snowpack can break into deeper weak layers, creating a more dangerous slide.
Use caution anywhere you find about eight inches or more of recently drifted snow. Fresh cornices, rounded pillows of snow, or a sculpted snow surface are signs of suspect slopes. Sheltered slopes less than thirty degrees without steep slopes above provide safer options.
On Saturday, two backcountry skiers triggered and were killed in an avalanche near Vallecito Reservoir, while a snowmobiler triggered and was killed in an avalanche near La Manga Pass. You can read the preliminary reports here and here. Our deepest condolences go out to the family and friends of the people involved in this tragic accident.