Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
View on map

Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
Out of date — this forecast expired 9 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The avalanche danger will remain LOW for all elevations for most of the day. As new snow accumulates this evening and overnight the avalanche danger will increase to MODERATE in near and above treeline terrain due to newly formed wind slabs. In addition, dangerously cold temperatures with wind chills below zero could pose problems for anyone out in the backcountry tonight. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Avalanches will remain unlikely until new snow starts to accumulate later today and this evening. Other hazards including long sliding falls on frozen icy crusts and collisions with exposed obstacles (or both) still exist. Strong winds before and during the storm and falling temperatures with wind chills that become dangerously cold could also pose threats to backcountry travelers especially those planning to spend the night outside. 

    Once new snow starts to accumulate this afternoon and evening, the avalanche danger will start to increase. New fragile wind slabs will form on wind-loaded N-NE-E aspects and cross-loaded NW and SE aspects in near and above treeline terrain. These wind slabs will start small and will grow in size as the snow accumulates. In the most heavily wind-loaded areas that receive the most new snow, they could grow large enough that avalanches involving these wind slabs could bury or injure a person this evening and during the night (or earlier if the snow arrives sooner than expected).

    If the frigid single-digit temperatures with wind chills below zero and winds gusting to ~100 mph are not enough to deter a person from backcountry travel tonight, then expect human triggered wind slab avalanches to become possible in wind-loaded areas this evening and during the night as well. 

Avalanche Discussion

* Observations yesterday from Chickadee Ridge (Mt. Rose backcountry) showed minor isolated, inconsequential wind slabs on some leeward slopes near ridgelines. Snow surfaces ranged from firm crusts in wind and/or sun exposed areas to soft snow in shaded wind protected areas. Snowpit data from this area indicated a well-consolidated snowpack below the surface. This data is consistent with other observations across the forecast area in the last several days.

* Recent strong winds have scoured many exposed near and above treeline slopes down to firm crusts.

* Thin snow cover conditions exist throughout the forecast area on all aspects at lower elevations. Thin snow cover or bare ground exists on most sun-exposed aspects at all elevations with a few notable exceptions.

Regions covered