Lawinenlagebericht

Central Sierra Nevada

Sierra Avalanche Center
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Lawinengefahr

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

Kernpunkte

In specific terrain, you still might trigger an isolated, but sizable avalanche due to lingering poor snowpack structure. Choose terrain intentionally, assessing the potential consequences of an unexpected avalanche. At this time, it remains wise to select terrain not capable of producing large avalanches.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1.5–2.5

    Weaker faceted snow that lingers at the bottom of the snowpack is gaining strength over time. Seven days have passed since the last report of an avalanche that failed on this weak layer, and four days since the last reported snowpack collapse. Clearly, it has become harder to trigger an avalanche on this weak layer. However, snowpit test results indicate with sufficient frequency that an avalanche could still occur. Any isolated avalanches that fail near ground level will easily be large enough to bury a person, maybe even break a tree or two. This puts us in the realm of a low likelihood, high consequence event.

    The areas where poor snowpack structure is most prominent is across NW-N-NE aspects above about 8000' to 8500'.  In isolated areas, a snowpack structure conducive to this avalanche problem has also been observed on E aspects. Additionally, there remains some graupel in the upper portion of the snowpack that has yet to bond into the snowpack and might still be able to contribute to a more shallow avalanche.

    The easiest way to avoid this avalanche problem is to choose slopes less than 30 degrees in slope angle, without steeper connected terrain above or to the side. A bit more nuanced is to seek out slopes below about 8,000' where previous rain destroyed the weak layer at the base of the snowpack. Don't expect to see much if any indications of snowpack instability outside a snowpit dug in a very well chosen location. Terrain selection remains critically important right now for avalanche avoidance.

    (11/26/2024)

    There is a distinct difference in snow at the bottom of the snowpack where this avalanche problem lingers. Not all areas gain strength at equal rates. Spatial variability leads to lingering concern for isolated instability.

    Photo: Sierra Avalanche Center, NNW aspect at 9,650' near Incline Peak, NV.

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