Bollettino valanghe

Eastside Region

Eastern Sierra Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

MODERATE avalanche danger exists at all elevations today. Evaluate snow and terrain carefully and use terrain choice to mitigate your exposure to potential persistent slab avalanches. Wind slabs of varying size and sensitivity will also be possible to find near and above treeline today on northerly and easterly aspects.

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3

    Our recent storm snow has begun to consolidate into a supportable and cohesive blanket of new snow.  Overall this is beneficial for our snowpack however in areas that held snow prior to this storm, a robust and consolidating slab is now resting on a weak and unconsolidated base. The distribution of snow before this storm could best be described as a patchwork, making this problem exceedingly difficult to predict and manage. Northerly and easterly aspects above 9000’ are of greatest concern however we are not ruling out the broader distribution range of W-N-E-SE.

    Persistent Slab problems challenge our patience, and managing this problem requires extensive evaluation and deliberate terrain choice. While becoming less sensitive over time, avalanches breaking on these lower weak layers have the potential to be large and destructive. 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, they can be 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

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2.5

    Quiet weather and continued light winds will limit the potential for fresh wind slab development today, however, lingering wind slabs in northerly and easterly terrain have the potential to be quite large and may still be reactive to human trigger. Exposed areas and leeward catchment zones near and above treeline deserve elevated caution. 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.

Avalanche Discussion

Our current weather pattern will be a powerful draw to the backcountry enthusiast today however as we enter a period of quiet weather it will be important to remain vigilant. Significant uncertainty remains regarding the distribution of our persistent slab problem as well as the speed at which these week layers will adjust to the new load. What is more certain is that an avalanche resulting in these lower week layers has the potential to be very large and destructive. Objective evaluation and deliberate terrain choice will be your best tools. Periodic probing can be an effective way to identify the presence of old snow as you move through the backcountry today. Don’t be afraid to dig in to have a look at the lower reaches of the snowpack and be on the lookout for signs of unstable snow such as collapsing or shooting cracks. When in doubt remember that picking less consequential terrain is always a good option for reducing risk.

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