Avalanche forecast

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Human triggered avalanches remain likely today due to the combination of recent snowfall, wind, and buried weak layers. Weak layers of snow are now buried 1-3 feet below the snow surface on most aspects and elevations, but could be deeper in specific terrain. Avalanches may be triggered remotely—from gentler terrain above, below, and to the sides of steep slopes. Conservative decision making and cautious route finding are advised. 

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2.5

    There are several weak layers buried within 3 ft of the snow surface. The most recent storm from 12/21-22 has placed a continuous slab on top of these persistent weak layers, creating the necessary conditions for avalanches. Areas where the wind has stiffened this new snow into thick slabs are of particular concern.

    A layer of near surface facets and surface hoar was buried in early to mid December. This layer is about 1.5 feet or so below the surface of the snow. The distribution of this layer remains uncertain. On December 22 Forecasters Antonioli and Drinkard were able to remotely trigger avalanches on this layer in Snake River Canyon region of the forecast area (see observation). With 3 nights of frigid temps and little to no snow the reactivity of this layer has likely decreased, but surface hoar is a particularily nasty problem. Avalanches involving this layer will likely be on the smaller side but could occur in and around terrain traps. Use you shovel to see if the thin grey line is present 1-1.5 feet below the snow surface. Be extra cautious in any drainage within the Greys Zone that has large amounts of open water (rivers and creeks). These are the drainages that grow surface hoar the fastest due to the amount of available water vapor. 

    The November 27 layer is widespread and is now buried around a meter deep at the upper elevations.

     Avalanches may be triggered remotely—from gentler terrain above, below, and to the sides of steep slopes.

    (12/22/2022)

    Natural avalanche activity on surface hoar in the Greys

    Photo: Antonioli

Avalanche Discussion

The most recent storm system dropped 6-12 inches of snow throughout the Greys River zone. The frigid temps from the last 3 nights have allowed this most recent snow to settle into slabs that are 1-1.5 feet thick. These slabs rest on weak layers of snow that date back to mid November, including a layer of buried surface hoar which likely formed some time in the early to mid December timeframe. Surface hoar is a particularly nasty weak layer due to its sensitivity and propensity for causing remotely triggered avalanches. If avalanches fail on this surface hoar layer they will likely be around 1.5 feet thick, but if they fail or step down to lower weak layers they could be up to 3 feet thick or more. Wind loaded areas are of primary concern, but with the extreme wind that occured on December 20/21 these areas could be further downslope than traditional starting zones. 

Regions covered