Avalanche forecast

Central Sierra Nevada

Sierra Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

A quick cold storm has brought enough wind and snow for people to trigger avalanches today, especially in the northern part of the forecast area. Watch out for open slopes, slopes near ridges, and gullies where wind-blown snow has piled up, and steep slopes in sheltered areas with more than about 4 inches of new snow. Make plans targetting areas out of the wind and less steep slopes to reduce the risk of triggering an avalanche. 

Avalanche problems

  • Wind Slabs

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

    New snow and gale-force winds have piled slabs of wind-drifted snow onto the leeward sides of ridges, in gullies, and on open slopes exposed to wind-loading. The winds should remain strong enough to keep loading snow onto these areas today. Some wind slabs may even exist below treeline due to the strength of the wind. The largest and most fragile wind slabs will exist in the northern part of the forecast area where the most snow accumulated. Wind slabs will be smaller in the southern part of the forecast area where less snow fell. 

    Cornices above a slope, blowing snow, smooth drifted snow,  and wind-created snow surface textures can all help identify where wind slabs may exist. Recent avalanches and cracking in the wind-loaded snow represent sure signs that wind slabs are unstable. Traveling in terrain sheltered from the wind can help reduce the risk of accidentally triggering a wind-slab avalanche and help lead your group to more consistent snow conditions. 

    (4/1/2023)

    An example of a shallow but problematic wind slab avalanche that took a skier down this slope on Red Lake Peak in March this year. 

    Photo: Public

  • Storm Slabs

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

    In the northern part of the forecast area, enough snow may have accumulated to form a cohesive layer of storm snow on top of yesterday's melt-freeze crusts. Some storm snow weaknesses may also exist in the new snow. Storm slab avalanches may be possible on steep slopes in sheltered areas with more than about 4 inches of new snow. In the southern part of the forecast area, where less snow fell, storm slab avalanches are less likely. The new snow may still sluff off yesterday's crusts on steep slopes where the underlying crusts are smooth. 

    Getting out of existing tracks to look for cracking in the storm snow and feeling for different layers of snow as you travel through the terrain can help identify where storm slabs may exist. Recent avalanches or failures on small test slopes also provide obvious clues to ongoing instability. If you see any signs of storm snow weakness or doubt a slope's stability, bypass that area for somewhere without signs of instability. 

    (3/25/2023)

    Small shallow skier-triggered soft slab sliding on an old rain crust on Maggies Peak in March.

    Photo: Public

Avalanche Discussion

  • Frozen melt-freeze crusts exist below the new snow. Those crusts were smooth in some places and rough in others. 
  • Glide cracks have started to form on some steep slopes in rocky areas. The exact timing of glide crack avalanches is notoriously difficult to predict. Due to the uncertainty, consider avoiding travel on or below slopes with glide cracks.
  • Large cracks have opened up behind many cornices, and falling into one of them could cause problems.

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