Central Sierra Nevada

Avalanche problems

• 

  Wind Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Unlikely

  Size

  1–1.5

  As the winds increase today, some blowing snow may occur around ridges. Since the amount of soft snow available for transport remains limited, the formation of problematic wind slabs should remain unlikely. Still, keep an eye out for areas where the blowing snow piles up, especially if the blowing snow seems more intense than expected. Keeping track of these areas can also help identify where larger, more dangerous wind slabs may form during the storm.

  

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Unlikely

  Size

  2–2.5

  Most data and observations indicate that while weak snow still lurks in the lower portion of the snowpack on NW-N-NE aspects above about 8500 ft, these layers have adjusted to the current load above them. Some tests still produce unstable results and indicate that these layers could reactivate if enough new loading occurs. Persistent slab avalanches should remain unlikely today. Some uncertainty still exists around these layers. A slim chance may still linger for a persistent slab to release in some isolated spot where an unusual amount of wind loading happens.

  Even though these avalanches may be unlikely, keep looking for any signs of unstable snow, like snowpack collapse or whumpfing sounds. If you see a place with 8 to 12+ inches of newly drifted snow on NW-N-NE aspects near and above 8,500 ft, consider that might be one of those isolated spots where a slim chance for a persistent slab may still linger. The likelihood of encountering this much wind-drifted snow should remain low, but the consequences of triggering an unexpected avalanche could be substantial.