Lawinenlagebericht

Salt River and Wyoming Ranges

Bridger-Teton Avalanche Center
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Lawinengefahr

Mon
Hochgebirge
2 · Mässig
Waldgrenze
2 · Mässig
Unterhalb
Keine Stufe
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Veraltet — dieser Lagebericht ist 3 years ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

While unlikely, the chance exists for backcountry travelers to trigger a large avalanche that fails on weak snow in the lower half of the snowpack. Shaded terrain at the middle and upper elevations that is steep, rocky, and unsupported could produce a destructive avalanche. In addition, be on the lookout for small pockets of wind-drifted snow in exposed terrain at the highest elevations.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely
    Größe
    1.5–2.5

    Slabs of cohesive snow 1-3 feet thick overlay weak, faceted snow that formed during a dry period in November. While unlikely, the potential exists to trigger an avalanche at this interface on northwest through northeast aspects above 8,500’. Collapsing the weak layer in a shallow portion of the snowpack, especially in very steep and unsupported terrain, is the best way to trigger one of these avalanches. Keep in mind that a slope can be ridden several times before a particularly thin, weak spot is impacted. 

    The snowpack in the Greys River forecast area varies significantly between the Salt River, Wyoming, and Snake River Ranges. As a result, slopes where the persistent slab problem can be found will differ slightly from one range to another. What remains consistent is the fact that avalanches can happen anywhere weak, sugary snow sits beneath a stiff slab. Digging into the snowpack is the only way to know for sure if this problem exists. Trenching your snowmobile or probing with a pole to feel for hardness changes (hard snow over soft snow) are easy ways to identify this layer. Remember that a slope 50 yards away from the one you just dug on will likely hold a different snowpack.

    Yesterday’s 2-4” of snow combined with moderate winds out the west have created very shallow soft slabs (3-6”) on leeward aspects above 10,000’. These slabs are mostly harmless to humans except in extreme terrain where being knocked off one's feet could carry severe consequences.

    (12/21/2023)

    Here is a good example of the terrain where triggering a persistent slab is most likely. These avanches occured during out last storm cycle. 

    Photo: Alex Drinkard

Avalanche Discussion

Nearly two weeks without a significant loading event has given the weak snow in the lower half of the snowpack time to adjust to the load from the early December storms. Consequently, it has become difficult, but not impossible, to impact the weak layers in the lower half of the snowpack. Shallow, rocky areas near cliff bands are still great places to find a trigger point. If you choose to step out into steeper terrain, be cautious of terrain traps such as creeks and gullies. Even a small avalanche in a terrain trap can carry severe consequences. Although we are trending towards low avalanche hazard, it is important to practice safe backcountry travel habits. This means exposing only one person to avalanche terrain at a time and stopping in appropriate safe zones.

Snow coverage at the lower and middle elevations remains thin in the Greys River zone. This makes access to the upper elevations challenging. In addition, many obstacles are lurking just beneath the snow surface.

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