Lawinenlagebericht

Central Sierra Nevada

Sierra Avalanche Center
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Lawinengefahr

Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
Veraltet — dieser Lagebericht ist 9 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

MODERATE avalanche danger exists in near and above treeline terrain due to yesterday's lingering wind slabs and today's newly formed wind slabs. Small loose dry avalanches could also occur on steep slopes where loose unconsolidated surface snow exists in more sheltered terrain. Human triggered avalanches remain possible today. Evaluate snow and terrain carefully; identify areas where avalanche problems exist; and avoid those areas.

Lawinenprobleme

  • Wind Slabs

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

    Strong NE winds will transport snow away from previously wind-loaded N-NE-E aspects and create new wind slabs on the S-SW-W aspects and cross-loaded NW and SE aspects. These new wind slabs may be sensitive to human-triggering today and human-triggered wind slab avalanches will be possible. In addition to these newly formed wind slabs, some of yesterday's wind slabs may still linger on wind-loaded N-NE-E aspects and cross-loaded NW and SE aspects in areas that have not been scoured by the NE winds. In either case, these wind slabs exist on top of smooth icy surfaces and weak old snow. While many of these wind slabs should remain small and not extend very far away from ridgelines, some larger and deeper wind slabs could exist in the most heavily wind loaded areas or in areas that received the most new snow. Avalanches resulting from these wind slabs could involve enough snow to bury a person. The wind slabs should be denser and harder than yesterday's wind slabs. They could break above the person who triggers them or not fail until that person has already committed to the slope.

    Use clues like blowing snow, hollow sounding snow, cornices above slopes, drifted snow, and other wind created textures to identify where wind slabs may exist and avoid traveling on or under steep slopes in those areas in favor of less exposed, less steep, more sheltered slopes where softer snow may reside.

  • Wet Slabs

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

    A cold clear night should have caused yesterday's snow to weaken and become less cohesive in areas sheltered from the winds. While weaker surface snow means slab avalanches should be unlikely in sheltered near and below treeline areas, loose dry sluffs could occur today. Steep slopes where the new snow rests on top of smooth icy old snow surfaces or on top of loose weak old snow represent the most likely terrain to trigger a loose dry avalanche. These sluffs could involve enough snow to knock a person off balance but may not involve enough snow to bury a person. With the current early season conditions, getting knocked off balance could result in getting pushed into a rock, tree, stump or other hard immovable objects. These sluffs would could also have more serious consequences in areas near cliffs or other terrain traps. 

Avalanche Discussion

* Small but reactive wind slabs existed on Castle Peak and Chickadee Ridge yesterday. Ski kicks caused shooting cracks and small 6 to 14 inch deep wind slab failures on N-NE-E facing test slopes. Variable old snow exists under these wind slabs ranging from firm crusts to old hard slabs. 

* Snow totals averaged about 4 inches across the forecast area yesterday.

* Weak snow still exists under the new snow in sheltered areas, but the new snow did not have enough slab characteristics to form a storm slab problem.

* The most snow coverage still exists in areas north of Emerald Bay above 8,000'. Below 8,000' snow coverage remains patchy and shallow. South of Emerald Bay, less snow exists with areas below 8,500' holding very little snow. 

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