Avalanche forecast

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Avalanche danger

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

Incremental loading of new snow this last week with moderate wind has created firm cohesive slabs in upper elevations as well as stressed buried weak layers making human triggered avalanches possible. Wind slabs will be confined to exposed terrain in the upper elevations. The snowpack varies drastically across the zone, with increased avalanche activity in areas with a shallower snowpack such as the Wyoming Range. These buried weak layers are difficult to access, so avoid consequential terrain in wind loaded and shallow areas. 

A snowmobiler triggered avalanche was reported yesterday near Afton in Dry Creek Lake resulting in a burial on consequential terrain. Further details are unknown, but we will continue to update on the incident as we receive more information.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Consistent snowfall during this last week combined with moderate S/SW winds has formed wind slabs that range 6 to 20 inches deep. These slabs will be most concerning in the upper elevations, but could be found in isolated features in the middle elevations. Areas with the highest likelihood of encountering a wind slab are exposed terrain such as ridgelines, cirques, or confined features like couloirs. 

    Watch for increased instability of new snow during periods of rapid warming on solar aspects if the forecasted cloud cover dissipates by this afternoon. Solar input on snow surfaces increases significantly this time of year with the arrival of spring.

     

     

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    The Feb 18th weak layer of concern is buried 2-3 feet above a firm, cohesive slab. Recent avalanche activity has occurred on this layer in areas with a thin, shallow snowpack such as the Wyoming Range (Dry Creek Lake, Hoback Peak).  This layer is composed of a facet, crust combination found on solar aspects in the middle and upper elevations. Lower elevations contain this same combination, as well as weak, faceted snow on sheltered aspects. Avoid consequential slopes over 30° in these shallow areas. The drastic variation in the overall snowpack in the Greys makes this problem difficult to manage. The best way to assess this weak layer is to dig down, identify the layer, and perform stability tests before riding consequential terrain.

     

    (3/2/2023)

    This avalanche resulted in a partial burial of a rider on a west aspect in the Hoback section of the Greys at 9,700'.  

Avalanche Discussion

Complacency

This last week brought a plethora of new snow creating excellent powder riding conditions. New snow instability has decreased, leaving wind slabs as the main avalanche concern in the upper portion of the snowpack. Yesterday afternoon, cloud cover broke in certain areas creating rapid warming of snow surfaces. This was the first significant warming of new snow that fell during cold conditions. This first wave of rapid warming causes increased instability of snow on solar aspects. Cloud cover could dissipate by this afternoon, so monitor the effect of direct sunlight on those southerly and westerly aspects. 

With the quick approaching arrival of spring and as new snow settles, it’s easy to become complacent assuming the snowpack has stabilized. Unfortunately we still have a complex snowpack. Two snowmobile triggered avalanches resulting in burials have occurred in the Wyoming Range recently. Snowpack characteristics in this area are much more unstable as a result of a shallow snowpack with increased reactivity of persistent slabs. Other areas of the Greys contain this similar poor snowpack structure. Due to the large variability in the snowpack across this zone, it is vital to continually assess the snowpack and terrain. It has been a long season, don’t let complacency throw off your mind set. Consequential terrain should always be thoroughly assessed as snow constantly evolves to changing weather conditions. 

Regions covered