Bollettino valanghe

Eastside Region

Eastern Sierra Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Wind slabs ranging in size and sensitivity may be possible to find in leeward catchment zones on all aspects near and above treeline today. Steep open bowl features and mid-slope depressions on northerly and easterly aspects are areas where older and more cohesive wind deposits are resting on weak underlying snow and it may be possible to trigger a dangerous hard slab avalanche. Be particularly wary of terrain features that elevate the consequences of an avalanche.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    While decreasing winds today will limit the potential for fresh slab development, small amounts of new snow combined with strong and shifting winds created wind slabs in leeward catchment zones on all aspects over the past 48 hrs. While these more recent deposits may still be reactive to human triggers and deserve your attention, larger more consequential avalanches may be possible to find on northerly and easterly terrain features where older, dense, wind deposits are resting on weak underlying snow. Recent avalanche observations suggest the most likely areas to find these hard slabs are mid-slope depressions further down from ridgelines than you may typically expect and in catchment zones near treeline. Hard wind slabs may feel strong under a rider's weight but they can fail suddenly and unexpectedly, accelerating quickly, and traveling long distances down slope. Watch for clues like blowing snow, large fresh drifts, and hollow upside-down feeling snow. Be suspect of terrain features that encourage drifting, such as the leeward sides of ridgelines, alpine couloirs, mid-slope convex rollovers, and cross-loaded depressions.

    Wind slab avalanche, Lundy canyon (02-14/2023)

Avalanche Discussion

Over the past couple of weeks, we have been discussing the poor structure in the upper snowpack where dense wind deposits are resting on weak and faceted snow. While in many areas surface snow was largely unconsolidated last week, over the last few days modest snowfall and strong winds have impacted the region. As a result, we have seen surface snow stiffen into a more cohesive slab. Field observations have highlighted several recent avalanches that fit into this pattern. Make no mistake, this is a tricky situation to navigate. Shaded northerly and easterly aspects will be areas where this structure is more likely to reside, particularly, in mid-slope depressions and in leeward catchment zones near treeline. It is important to remember that hard slab avalanches often break without warning, they can fracture above you, and propagate quickly. Keep in mind that even a small avalanche can have large consequences in complex and challenging terrain.

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