Bollettino valanghe

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Pericolo valanghe

Tue
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

Recent snow and wind combined with buried weak layers make human triggered avalanches possible in the middle and upper elevations. These buried weak layers have a sporadic distribution making them difficult to predict. Take a cautious approach to manage this uncertainty and avoid areas with evidence of wind loading such as drifts and stiffened surfaces.

Problemi valanghivi

  • Persistent Slabs

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

    Weak layers of snow formed in November and December are buried 1-3 feet deep. These weak, sugary facets are widespread across most aspects and elevations with increased sensitivity in terrain with a shallow snowpack. A layer of surface hoar and near surface facets from December is also buried in the top 2-3 feet. This layer is particularly difficult to manage due to its scattered distribution and reactive nature. Digging a snowpit in one location may not identify this layer. Use extra caution in terrain sheltered from the wind where this layer was preserved and buried. 

    (1/5/2023) Photo: Antonioli

    Persistent slab avalanche in the Wyoming Range. 9500' SE aspect

  • Wind Slabs

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

    Moderate winds out of the south and southwest continue to deposit snow on a variety of aspects in the upper elevations creating wind slabs less than 12 inches deep. Although warm temperatures have reduced the snow available for transport, old slabs may still be reactive. Be aware that new snow from last night could cover previously wind loaded terrain making them difficult to identify.

Avalanche Discussion

The Greys forecast zone covers a massive area encompassing vastly different mountain ranges and snowpack characteristics. This makes the persistent slab problem very difficult to manage, especially when dealing with surface hoar or near surface facets. Given their sporadic distribution, these weak layers are generally hard to predict even in a confined area. Increase the size of that area and the problem becomes even more difficult to predict. Due to this uncertainty, it’s important to take a bit of extra time to access snow stability and match terrain choices accordingly. In many instances, the choice that may seem less appealing but overall safer will be the more conservative one during persistent slab problems. 

Yesterday observations found a widespread melt freeze crust across all aspects up to 9000’ on the west side of the Salt River Range and . Over on the Wyoming Range where temperatures remained cooler, these crusts were confined to southerly aspects. With an incoming storm system it will be important to assess how this new snow will bond to existing surfaces. Quick and rapid loading could create unstable conditions with new snow. 

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