Lawinenlagebericht

Central Sierra Nevada

Sierra Avalanche Center
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Lawinengefahr

Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 7 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Unstable slabs of wind drifted snow may still exist on leeward facing slopes in near and above treeline terrain. Human triggered wind slab avalanches remain possible today. MODERATE avalanche danger exists near and above treeline with LOW avalanche danger below treeline.

Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1

    Stong SW winds have drifted the recent snow onto wind-exposed NW-N-NE-E-SE aspects. Adding a person's weight to these slabs of wind drifted snow could still result in a wind slab avalanche. In most areas, these wind slabs should remain small and may only knock a person off balance (D1). In the areas that received the most snow in recent days, human triggered wind slab avalanches could involve enough snow to bury or injure a person (D2).  

    Stay alert for areas where possibly unstable wind slabs may exist by looking for clues like cornices above a slope, drifted snow, scoured ridges with smooth snow on one side, and wind-created surface textures. Use this information to plan travel routes with safety margins that appropriately manage this potential hazard. 

       

    Photos: Cornice and human triggered shooting cracks in wind slabs on Castle and Andesite yesterday.

Avalanche Discussion

* In wind-exposed terrain on Castle Peak and Andesite Peak yesterday, large shooting cracks occurred on wind-loaded slopes. Most of the skier triggered cracks extended 10 to 20 ft. One cornice dropped onto a slope on Castle triggered shooting cracks 70 ft wide. Observers also reported seeing wind slab avalanches on steeper slopes nearby. Wind slabs in these areas measured between 10 and 24 inches deep. Small inconsequential areas of wind drifted snow also existed on Echo Summit where less new snow accumulated. 

* A layer of weak snow (facets) still exists near the Dec 12 and Jan 4 rain crusts. This layer does not have a slab on top of it yet, but snowpit tests that simulate adding new snow (like what we are forecasted to get later this week) indicate that this layer could fail. Check out the loaded PST video from Jan 10.

* Consolidated snow exists in the middle and lower portions of the snowpack and should handle the new snow loading well.

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