Lawinenlagebericht

Central Sierra Nevada

Sierra Avalanche Center
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Lawinengefahr

Hochgebirge
1 · Gering
Waldgrenze
1 · Gering
Unterhalb
1 · Gering
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Veraltet — dieser Lagebericht ist 11 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

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. It is still early season and the snowpack is relatively shallow. Numerous barely covered rocks, stumps, logs, and other hazards exist.

Lawinenprobleme

  • Cornices

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

    The current snowpack stability is good in many areas. However in specific areas, day after day field observations indicate potential isolated pockets of instability and the potential for developing avalanche problems in the short term. Faceted weak layers reactive to snowpit tests are continually found near treeline and below treeline on many but not all NW-N-NE aspects. These weak layers are usually found at the bottom of the snowpack and occasionally at mid height within the snowpack. In both cases there is an overlying slab. In areas where either of these snowpack structures exist, any signs of instability including collapse, whumpfing, cracking, or unstable snowpit test results are cause for conservative decision making. Small difficult to trigger (ie unlikely) avalanches are both an ongoing issue and a potential more significant future avalanche problem requiring both thought and a specific management plan while moving in and below avalanche terrain. Communicate with your travel partner(s), examine the snowpack, make a specific travel plan, stick to your plan.

Avalanche Discussion

Despite warming air temperatures at the mid and upper elevations, little change has occurred in the overall snowpack structure from one day to the next. 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 Rubicon Peak (West Shore Tahoe area), snowpit tests revealed sudden collapse and propagation results on basal facets near treeline and below treeline on both NE and NW aspects between 8,500' and 8,900'. This is very similar to what was observed the day before on Castle Peak (Donner Summit area) and in several other locations around the forecast area over the past week (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 certain 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. On the E-SE-S-SW-W aspects, a very shallow well anchored snowpack exists with the most recent new snow transitioning to melt-freeze layering. Numerous barely covered rocks, stumps, logs, etc present a significant hazard to over snow travel on all aspects.

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