Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

MODERATE avalanche danger at all elevations today due to the possibility of loose wet avalanches and unlikely wind slab avalanches.

Avalanche problems

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Rapid warming conditions are expected this morning before increasing high level cloud cover later today has a significant effect on reducing incoming solar radiation. Many locations at the lower and middle elevations remained above freezing last night, just above the inversion layer of cold air on the mountain valley floors. These areas already have a head start on warming prior to sunrise. Small loose wet avalanches are expected again today with most instability occurring on E-SE-S-SW-W aspects. Loose wet avalanches are expected to a lesser degree on NW-N-NE aspects but are increasingly possible as higher spring sun angles have more influence on northerly aspects. Avalanche size D1 is expected today with the possibility of an isolated size D2.

    Rollerballs and pinwheels will be the indicators that loose wet instability is present. Consequences from what would otherwise be a small inconsequential size D1 avalanche will come from secondary terrain hazards such as being pushed into rocks, trees, over cliffs, or into terrain traps. Use low angle slopes to reduce the hazard as needed. Plan appropriately for the timing of travel in sun exposed avalanche terrain and exit steep terrain before daytime warming creates problematic instability.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1

    A wind slab avalanche problem is unlikely today but there are a couple of things going on. First, isolated wind slab instability lingered unexpectedly into yesterday with a couple of human triggered size D1 avalanches reported. Second, ridgetop winds are strong today and will be able to drift what little snow remains available for transport in ridgetop areas. Isolated human triggered wind slab avalanches are unlikely but not impossible today in near treeline and above treeline terrain on NW-N-NE-E aspects.

    Look for signs of recent wind slab avalanche activity from the past two days and keep an eye out for any areas of blowing snow. Exercise normal caution around these areas, taking into consideration how terrain may magnify consequences of a small unexpected avalanche. 

Avalanche Discussion

* Numerous natural and human triggered loose wet avalanches were reported yesterday around the forecast area on sun exposed slopes. Avalanche size was almost all D1 with one report of a size D2.

* A couple of isolated human triggered size D1 wind slab avalanches occurred yesterday, but wind slab avalanches were very limited relative to the number of people moving through recently wind loaded terrain.

* Recent avalanches have all been focused around the layer of snow at the surface, with the deeper snowpack generally well bonded and lacking problematic weak layers.

Regions covered