Avalanche forecast

Eastside Region

Eastern Sierra Avalanche Center
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Avalanche danger

Fri
Alpine
4 · High
Treeline
4 · High
Below
4 · High
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Highlights

HIGH Avalanche Hazard exists for the Eastern Sierra on ALL ASPECTS. Intense snowfall overnight (~20”) with continuing rapid accumulations, and loading southerly winds will make for very dangerous avalanche conditions. Travel in or below avalanche terrain is not recommended.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–3

    Significant wind slab will be found on W-NW-N-NE-E-SE Aspects especially at the High and tree-line elevations today. With ~20” of new snow overnight at 9000ft (Mammoth area) and significant totals projected during the day, there undoubtedly will be widespread, sensitive, wind slab  in the mountains. Strong to Extreme Southerly winds have been blowing all night and are projected to continue throughout the day for the highest elevations, loading slopes with transportable fresh snowfall.  Areas adjacent to ridgeline, cliff bands, rock outcroppings, and roll overs are all terrain features where wind slab will be exacerbated. Travel within or underneath avalanche terrain today is not recommended. Slides could be large to very large and run long distances. Pay attention, and know what is above you especially with minimal visibility to reduce exposure to avalanche hazard.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–3

    With close to 20” of snow falling overnight, (focused on the Mammoth area), and potentially a lot more snow on tap for today, be aware of new soft storm slab throughout the zone.  Consider ALL ASPECTS at ALL ELEVATIONS for this problem as snowfall is expected to be rapid and intense. Travel in avalanche terrain is not recommended as this rapid snowfall will be sensitive and reactive to human trigger, especially in steeper 35+ degree terrain. Shooting cracks, audible whumpfing, and fresh fat looking slopes are signs of building storm slab.  Overnight snowfall was less, but not insignificant in other parts of the forecast zone ranging from 6-9” in sheltered mid-elevation weather plots from Virginia Lakes down to Big Pine.

  • Persistent Slabs

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

    The intense snowfall, extreme winds, and rapid loading will test the weak old snow that resides at the base of the snowpack throughout the forecast zone. This moisture laden storm with heavy water content will add a lot of weight to underlying weak snow and avalanches could “step down” into old weak snow layers creating large and destructive slides. Areas of most concern are from around 9200ft to 10000ft in sheltered Northerly-Easterly terrain within trees. Weak old snow does exist widely and the condition should be considered on most aspects W-NW-N-NE-E-SE. Although we have found strengthening conditions at the interface between the old autumnal snow and last weeks big storm, this new additional load has the possibility of providing the trigger in exceptionally weak spots such as steep boulder strewn terrain with lots of cavities or convex roll overs.

     

Avalanche Discussion

With rapid intense snowfall and potentially deep accumulation today, especially in the Mammoth area, be aware of your surroundings  in regards to roof avalanches and hazards of deep snow immersion especially in regards to small children and pets. If out recreating/riding/skiing, pair up with someone, and avoid tree wells or other depressions where deep snow immersion is a concern.

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