Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Old, weak, sugary, snow continues to exist near the base of the snowpack below the most recent storm snow.  Avalanches will remain possible where strong snow exists above this weak snowpack.  Increased consequences continue to exist of any avalanche involvement due to the rocky and shallow snowpack. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    Old faceted weak snow exists on most NW-N-NE aspects below the most recent storm snow.  The exact structure and weakness of the snowpack varies widely by location and elevation.  Areas with wind blown snow or consolidated recent storm snow, could provide all the ingredients for a persistent slab avalanche to occur.  Previous wind scouring may have left some of the weakest snow in locations for mid or lower on the slope avalanches to occur.  If a persistent slab avalanche did occur, it could break wider than expected and could be remotely triggered.

    Any signs of instability like recent avalanches, shooting cracks, whumpfing sounds, or snowpack collapses would indicate an unstable snowpack in your area.  Use low-angle, non-avalanche terrain not connected to steeper areas above or beside it if you see signs of instability.  If an avalanche did occur, it could result in serious trauma from all the exposed rocks and current shallow snowpack.

    (12/9/2023)

    While skinning up this slope near an N-facing area at 9800 ft on Tamarack Peak, the group remotely triggered shooting cracks and a collapse that sounded like "thunder."

Avalanche Discussion

A weak faceted (sugary) snowpack exists above about 8,000', but could be encountered as low as 7,200' in isolated locations. As elevation increases expect to find layers of faceted snow in between rain crusts. Above about 8,500' or so, rain crusts disappear and the snowpack becomes nearly all weak faceted snow. Generally speaking, the higher up you go on wind protected NW-N-NE aspects, the weaker the snowpack.  Early season NE wind events previously scoured some exposed slopes down to dirt, rock, or ice.  This makes the distribution and location of the weak faceted snow more variable through the forecast region.

There is still the potential to hit many obstacles (rocks, logs, open water, bushes, etc.) that are barely covered (or not) by the shallow snowpack. Areas with a supportable mid snowpack rain crust in the 7,500’ to 8,500’ elevation range provide the most usable snowpack. Anticipate encountering a different snowpack structure and a different set of travel conditions if you are moving from one place to another around the forecast area.

Regions covered