Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Alpine
1 · Low
Treeline
1 · Low
Below
1 · Low
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Highlights

The avalanche danger should remain LOW at all elevations and on all aspects today since only 1 inch of new snow is expected. As new snow and wind impact the forecast area tonight, the avalanche danger will rise quickly. A variety of avalanche problems including wind slabs, storm slabs, and some scattered persistent slabs could become possible by tomorrow. Continue to use normal caution when traveling in the backcountry.

Avalanche problems

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Cold new snow falling on top of smooth frozen snow surfaces means that loose snow sluffs will become possible today. These sluffs should remain very small and inconsequential since only 1 inch of new snow is expected. As more snow accumulates tonight and tomorrow, these sluffs may become larger and more widespread. By tomorrow morning storm slabs could replace the loose dry snow sluffs as a potential avalanche problem depending on the amount of new snow that falls tonight.

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1

    As new snow and wind begin to impact the forecast area today, new wind slabs will start to form on the leeward aspects in near and above treeline terrain. With only an inch of accumulation expected today, these wind slabs should remain very small and not pose a hazard to backcountry travelers unless much more snow than forecasted accumulates. As more snow accumulates tonight and tomorrow, the wind slabs will grow in size and become more widespread. Think of the tiny wind slabs and drifts that start to form today as a preview of where larger and more serious wind slabs will exist tomorrow.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1

    On some isolated near and below treeline NW-N-NE wind sheltered and shaded slopes above 8000 ft, a layer of weak sugary snow (near surface facets) up to 6 in. thick does exist at or near the snow surface. This soft weak layer of snow rests above a frozen rain crust that could serve as an efficient bed surface for snow to slide on. Today's 1 inch of new snow will not add enough of slab above this weak layer/bed surface combination to overload it, so persistent slabs should not represent a problem for backcountry travelers today. However, the 6-12 inches of new snow predicted tonight and tomorrow could form slabs above this weak layer/bed surface combination. Like the wind slabs mentioned above, watch where new snow accumulates on top of the existing weak layer today to help figure out where more serious persistent slabs may exist tomorrow.

Avalanche Discussion

Hard frozen melt-freeze crusts dominated the snow surface on the northerly aspects on Waterhouse Peak yesterday. A few small isolated patches of soft weak surface snow 1-3 in. deep existed on some N aspects scattered among the frozen crusts. Similar to other northerly aspects around the region, some softer layers of weak snow did exist on top of a strong thick rain crust in the upper portion of the snowpack. This setup does represent a weak layer sitting on top of a bed surface that snow could slide on.

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