Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Wed
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Out of date — this forecast expired 3 years ago.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

Yesterday's storm fell way short of expectations but still added some weight to the snowpack and its buried weak layers. Triggering an avalanche several feet deep remains possible on slopes where weak snow lurks below the surface. These avalanches could come as a surprise in an area of seemingly stable snow. Travel plans that focus on lower-angle terrain can help increase your safety margins and reduce your exposure to the avalanche problem.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2.5–3

    Persistent weak layers remain buried in the snowpack, but yesterday's storm ended sooner and produced much less precipitation than expected. Still, the storm did add some load to the snowpack, and triggering a persistent slab avalanche may remain possible today. Some uncertainty also exists concerning the distribution, depth, and strength of these buried weak layers. Signs of instability on the persistent weak layers have decreased in some areas, but if these layers do fail, they could still produce very large and dangerous avalanches. In wind-loaded areas, persistent slab avalanches could be even deeper since more snow exists on top of these layers. The weakest snow exists in the Carson Range in the eastern part of the forecast area.

    As obvious clues of instability like recent avalanches, collapsing, cracking, and whumpfing decrease, it is easy to get complacent and assume slopes are stable. Still, persistent slab avalanches can occur on slopes without obvious clues, especially if you hit a trigger point where the weak layer is closer to the surface or where the overlying slab is thin. This scenario may even play out on a slope with tracks on it. Variability and uncertainty associated with the persistent slabs and their potential consequences make these problems difficult to manage. Using low-angle, non-avalanche terrain not connected to steeper areas above or beside can help reduce your chances of triggering an unexpected and dangerous persistent slab avalanche.

    (1/15/2024)

    This large natural avalanche between Lincoln and Anderson Peak is thought to have occurred on Saturday, January 13.  See the size of the crown relative to the people. It is an example of a persistent slab avalanche.

Avalanche Discussion

Yesterday's storm underperformed in almost every way: less wind, higher snow levels, and less than half of the forecasted snow load. Wet, dense snow on the surface and a lack of ongoing wind likely prevented wind slabs from growing. As a result, initial reports and observations make it seem like widespread avalanche activity did not happen.

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