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
3 · Marcato
Sotto il limite
3 · Marcato
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Avalanches will become more likely throughout the day as warm temperatures and intense sun heat up the mountains. The hazard level will increase to CONSIDERABLE as things thaw and water enters the snowpack. Avoid traveling on or under terrain that has become wet or slushy and give cornices a wide margin.

Problemi valanghivi

  • Loose Wet

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

    Wet loose avalanches and cornice falls continue to be the top problems today. We are in a spring weather cycle and each morning the hazard increases quickly as the sun and warm temperatures change snow surfaces. Once the snow begins its daily thaw, melt-water works its way down into the snowpack, weakening deeper weak layers. These conditions can lead to dangerous wet slab avalanches. It is difficult to predict when spring weather will lead to a more destructive cycle. Continue to track changing conditions, get clear of warming slopes when snow surfaces become wet and slushy, and be prepared to turn around earlier than expected. Wet snow may be a problem today at higher elevations.

    Cornice Fall: This is a significant hazard as temperatures warm each day. Large cornices have formed throughout the Greys zone and are being weakened by the daily spring thaw. Cornices should be given a large margin throughout this warming period. Travel on or under cornices is not advised. Be aware that they often fail far back.

    (3/17/2024)

    Wet loose activity on the southeast face of Ferry Peak.

    9,200'

  • Deep Persistent Slabs

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

    In much of the Greys forecast zone at middle and upper elevations, weak snow from December is buried up to 5 feet deep. The layer is very stubborn to human or snowmachine triggers in most locations but it continues to produce avalanches with each round of new snow, wind-loading, or cornice fall. These rapid changes in stress to the snowpack appear to be the most likely way to trigger an avalanche but don't overlook the potential to step on or ride over a thin spot which then causes a crack to propagate widely across a slope. Watch for cornices as you travel and evaluate convex slopes and thin, steep rocky, and wind-affected areas carefully. Terrain configuration and wind affect over time matter. Check out recent observations here and here for other examples of this problem.

    The best way to manage this avalanche problem is to build in a large margin for error in your intended route. Increase your safety margin by traveling where the snowpack is deepest, identifying the presence/depth of the weak layer (probing or digging), and avoiding thin, steep, rocky, and wind-affected areas. This problem can be hard to identify and will not show signs of instability like cracking or collapsing. Furthermore, tracks on a slope are not conclusive evidence of stability.

    (3/16/2024)

    An example of the type of steep, rocky terrain where deep persistent slab avalanches are most likely to be triggered.

Avalanche Discussion

The hazard rating in the Greys continues to reflect how the daily warming trend is expected to weaken specific slopes as thawing impacts stability. Cornices failing and wet loose slides are expected today and the potential for wet slab avalanches has entered the discussion. It is tricky to forecast for the implications of water in the snowpack. More northerly slopes may begin to see some of the wet loose activity that has been more common on solar aspects the last few days. As overnight lows rise throughout this high pressure system the snowpack is less and less likely to be as “locked up” in the morning. 

Backcountry travel this time of year should involve an awareness of snow surfaces and what time of day they are expected to thaw. Planning travel so that you are not on or under sun-impacted slopes or cornices as things warm up is important.

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