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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Out of date — this forecast expired 11 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

LOW avalanche danger continues for all elevations and aspects. The potential exists for the unlikely triggering of small avalanches in isolated areas. Continue to use accepted best practice travel techniques while traveling in or below avalanche terrain. Keep exposure limited to one person at a time and avoid grouping in avalanche run out zones.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1

    Inherently less stable early season snowpack conditions continue across the forecast area. In many areas current snow stability is good. In other areas that is not the case. Isolated pockets of instability are continually found near treeline and below treeline on NW-N-NE aspects. In some but not all of these areas, faceted weak layers are found below a slab either at mid height or at the bottom of the snowpack. In areas where this snowpack structure exists, any signs of instability including collapse, whumpfing, or unstable snowpit test results are cause for conservative decision making. Take time to investigate the snowpack and do not take stability for granted due to regional LOW danger. Difficult to trigger (ie unlikely) avalanches are an ongoing issue requiring some thought and management while moving in and below avalanche terrain.

Avalanche Discussion

Recent field observations continue to identify difficult to trigger problematic faceted weak layers in some but not all near treeline and below treeline areas on NW-N-NE aspects. Yesterday on Castle Peak (Donner Summit area), snowpit tests revealed sudden collapse and propagation results on basal facets near treeline on a NW aspect at 8,860'. Over the past week, problematic snowpit test results and at times skier triggered collapse and whumpfing were observed in other locations on N-NE aspects between 7,700' and 9,500' in the Donner Summit, Mount Rose, Pole Creek, Independence Lake, and Carson Pass areas (more info below). In areas where these weak layers are absent, no obvious signs of instability or unstable snowpit test results have been observed. Strong temperature gradients within portions of the snowpack indicate that faceting will continue in the short term.

Above treeline and on the sun exposed E-SE-S-SW-W aspects conditions are very similar across the forecast area. Pockets of wind scouring and wind drifted snow exist above treeline. Evidence of instability above treeline has been minimal and limited to very minor human triggered cracking of wind pillows and wind slabs over the past few days. On the sun exposed and wind protected slopes, a very shallow well anchored snowpack exists with the most recent new snow covering either melt-freeze layering or ground level rocks and vegetation.

Regions covered