Bollettino valanghe

Tetons

Bridger-Teton Avalanche Center
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Pericolo valanghe

Tue
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

Wind slabs at the high elevations could be triggered at the upper elevations. They are mostly likely to be found in very steep or extreme terrain, particularly near cliff edges where even the smallest of avalanches can carry dire consequences. A slight chance also continues at upper elevations to trigger deeper instabilities in the snowpack.  Larger slides are possible involving this layer and snowpack evaluation is recommended before committing to very steep terrain that has not been impacted, especialy in and around rocky areas and cliff bands. Avalanches at mid  and low elevations are unlikely except in isolated areas.

 

Problemi valanghivi

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1.5–2.5

    Weak layers, particularly one that was buried on January 26th, persist within the snowpack. These weak layers can be identified in snowpits at the mid and upper elevations although slab avalanches are only expected at this time in steep high elevation terrain where their occurence is unlikely but deserves consideration. Release of such as slab may require larger trigger such as a cornice drop or movement of a wind slab or possibly if a weak and thin spot on a slope is impacted. If triggered, these slabs could have depths of 2-3 feet, and are likely to release as hard slabs. 

    Deep Persistent Slab: In addition to persistent slab problem type, a  deeper weak layer persists on southeast through west aspects above 8500 feet. This layer is considered dormant at this time with last activity observed on January 16th. 

    (2/12/2023)

    South facing snowpit shows layers of crusts without presense of cohesive slab in this location. 

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Small surface slabs have been formed by southwest to northwest winds above 9000 feet. These soft slabs will be most sensitive in very steep terrain such as cliff areas and have depths of 6 to 10 inches. They will also become more sensitive as they are weakened by increasing temperatures and sunlight today. 

     

    Small wind slab avalanche on No Name Canyon where a skier was caught and carried requiring rescue from TCSAR.

Avalanche Discussion

The primary concern in the Tetons is small slabs along cliff edges that can carry severe consequences. The accident that occurred 2 days ago is an example of small slides causing big problems in unforgiving terrain. This avalanche concern is almost always present during the heart of winter and only during spring, diurnal conditions can the edges of cliffs be trusted. The persistent weak layers that can be found in the snowpack provide a completely different concern and approach. Although they can be easily identified, avalanche activity involving them is on the low side of unlikely.  Continue to be thoughtful of the weakness and approach very steep avalanche paths that have not been skied with a mindset of evaluation to determine if that path could be one where the recipe of weak layer and overlying slab could result in a human triggered avalanche. Yesterday’s observation of low elevation snow pack in the Snake River Canyon is worth mention as a reminder that in terrain that is currently stable, weak snow can persist that may (or may not) be a problem with future snow, rain, or warming. 

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