Storm Slabs
- Alpine
- Treeline
- Below treeline
- Likelihood
- Likely
- Size
- 1–2
Gale-force winds and rapid snow accumulation during this storm will likely create unstable slabs of storm snow on many slopes today. The new snow may accumulate faster than it can bond to itself or the old snow surfaces. Avalanches could occur in either wind-loaded or wind-protected areas across all aspects. In areas where wind-blown snow has filled in the downwind side of ridges, gullies, and open slopes, larger and stiffer unstable slabs of deeper storm snow will exist. Large and fragile cornices will also lurk above many of these slopes. In areas sheltered from the wind, these storm slabs will be less deep and softer but could still involve enough snow to bury or injure a person.
Conditions will change quickly today, and maintaining awareness of the changes will be challenging. Recent avalanches, test failures, or snow surface cracking offer clues that unstable storm slabs exist. Travel plans that focus on enjoying the new snow on lower-angle, non-avalanche terrain, without overhead hazards like other steep slopes or looming cornices, can help reduce your exposure to the avalanche problems today. Blowing snow and poor visibility may make implementing these plans more difficult today, so including wider safety margins or buffer zones in your travel plans will also be prudent.
Test slope failures like this one are a sure sign of unstable snow. This one was triggered back on Feb 13 on Mt. Judah, Donner Summit area, CA.
Photo: Public