Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Sun
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

CONSIDERABLE avalanche hazard exists at all elevations this morning However avalanche hazard is expected to rise to HIGH at Mid and upper elevations this afternoon as another round of heavy snowfall and continued strong winds impact the forecast area. Dangerous Avalanche conditions exist.  Natural and human-triggered avalanches remain likely.  Traveling on, near, or underneath avalanche terrain is not recommended.

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Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1.5–3

    Heavy snowfall and strong to extreme SW winds over the last several days have created dangerous wind slab conditions. With an additional 5-12” likely today and ample amounts of loose surface snow already available for transport, we can expect the size and distribution of fresh sensitive wind slabs to grow substantially today as Strong winds continue to impact the forecast area. Terrain features that encourage drifting such as the leeward sides of ridgelines, gully features, and cross-loaded depressions are all areas to avoid.  Large to very large Natural and Human triggered avalanches are likely today and avalanches may run long distances and into lower angle, or treed terrain you may typically think of as “safe”. Be cognizant of what is above you today, travel in, near, and below avalanche terrain is not recommended.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    Storm instabilities such as storm slab avalanches and loose surface sluffs have gained strength over the last 24hr as temperatures dropped and snowfall rates diminished.  However, 40+ inches of snow fell throughout the forecast area over the past 72 hr. It may still be possible to trigger a sizable storm slab avalanche today in sheltered areas and in steep unsupported terrain. Expect the Size and sensitivity of storm instabilities to increase this afternoon as another round of heavy snowfall impacts the forecast area bringing the potential for close to 12” of new snow by nightfall.

    Convex rollovers and slopes over 30° in steepness are potential problem areas. When in doubt, avoid being on or under avalanche terrain and be cognizant of your exposure to terrain features that increase the consequences of avalanches. This includes road cuts, gully features, cliff bands, and mid-slope depressions.

     

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    Prior to this major winter storm, forecasters were tracking on the weak faceted base to our snowpack. While we had begun to see some signs of healing in these lower weak layers in some areas, in others we continued to see weak structure and propagation propensity. It’s likely that our recent rapid loading event will have already stressed these lower weak layers past their breaking point, but it will be important to keep this poor structure in mind as the snow begins to settle. An avalanche occurring on these deeper weak layers is likely to be full depth and has the potential to be very large and destructive.

Avalanche Discussion

Merry Christmas and Happy Holidays from us at ESAC!

Enjoy the brief respite from the heavy snowfall this morning, another round of snow is expected this afternoon and into the evening. Extreme caution is advised if you decide to head into the backcountry today, over the past few days we have had several close calls including one full burial in the backcountry and an incident involving a roof avalanche in town. The risk of large and destructive avalanches is still likely. In addition, non-avalanche related hazards such as Deep Snow Immersion remain a concern. Partner up and be cautious around tree wells, in areas with deep unconsolidated snow, or under roof lines with large loads of snow.

Regions covered