Lawinenlagebericht

Eastside Region

Eastern Sierra Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 5 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

MODERATE avalanche danger exists at all elevations today. Persistent slab avalanches remain our main concern. Fresh wind slab development may also be possible near and above treeline on northerly and easterly aspects today as winds increase out of the Southwest. Evaluate snow and terrain carefully and use terrain choice to increase your safety margin and limit your exposure.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–3

    It has been several days since the last reported Persistent slab avalanche and as time goes on without a significant loading event these avalanches are becoming harder to trigger.  Nevertheless, recent field observations continue to show signs of unstable snow including collapsing, shooting cracks, and propagating test results. While large triggers such as a small wind slab avalanche or a cornice fall may be required to initiate a persistent slab avalanche today, shallow trigger points such as buried rocks or small trees are areas of concern for the backcountry traveler. These are areas where the weight of a skier/snowboarder may be enough to initiate slab failure. While becoming less sensitive over time, avalanches breaking on these lower weak layers have the potential to be large and destructive.

    Persistent Slab problems challenge our patience, and managing this problem requires extensive evaluation and deliberate terrain choice.  Don’t be afraid to investigate the lower reaches of the snowpack to see if old snow is present in the areas you wish to travel. This may mean digging all the way to the ground if you suspect old snow is present. Remember that persistent slab avalanches often propagate across and beyond terrain features that would otherwise confine surface instabilities such as wind or storm slab. Persistent slab avalanches can be triggered from lower angle terrain, the bottom of a slope, and in some cases, remotely triggered from adjacent terrain. Give yourself a wide safety margin, be wary of hazards that may reside above you, and use terrain choice to limit your exposure.

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Wind speeds increased overnight and are expected to continue out of the Southwest at moderate to strong speeds along ridge tops today.  Be on the lookout for fresh wind deposits on northerly and easterly terrain near and above treeline. Blowing snow, large drifts, recent cornice growth, uneven snow surfaces, and stiff hollow feeling surface snow are all clues that indicate nearby wind deposits. Do your own localized assessments and be suspect of terrain features that encourage drifting such as the leeward sides of ridgelines, gully features, and cross-loaded depressions. Keep in mind that even a relatively small wind slab avalanche may be enough to trigger a much larger persistent slab avalanche in the right location.

Avalanche Discussion

While our snowpack is largely on a healing trend, it is important to consider the complex nature of our snowpack if you decide to venture into the backcountry. Our persistent slab problem fits squarely into the category of “low likelihood and high consequence”, making it particularly hard to manage and predict. Choosing less consequential terrain such as areas where the weak layer does not exist or slopes under 30° in steepness, is your most powerful tool for managing the uncertainty surrounding this problem. Be sure to check out our recent observations for more information and enjoy the sunny skies, we may be in for an extended period of unsettled weather in the near future.

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