Lawinenlagebericht

Snake River Range

Bridger-Teton Avalanche Center
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Lawinengefahr

Fri
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Veraltet — dieser Lagebericht ist 6 months ago abgelaufen. Du siehst vergangene Verhältnisse, nicht den aktuellen Bericht.

Kernpunkte

Strong wind and significant snowfall has formed fresh wind slabs and added stress to buried persistent weak layers creating dangerous avalanche conditions. Triggering an avalanche is most likely on wind-loaded slopes, but still possible in sheltered terrain. Persistent slab avalanches are difficult to predict and could be triggered remotely from gentle terrain above, below, or beside steep slopes. Stick to lower angle slopes and avoid steep, wind loaded terrain as the snowpack undergoes rapid change.

Lawinenprobleme

  • Persistent Slabs

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

    Triggering a soft or hard slab avalanche up to 3 feet deep is possible on buried weak layers of facets and surface hoar, and more likely on northerly aspects. The highest concentration of avalanche activity over the last week was from 8,000’-9,500’ on sheltered N-NE aspects. Other aspects cannot be ruled out given the spotty distribution of these weak layers. For this reason, some slopes may appear stable while others are not. Knowing which slopes contain weak faceted snow or surface hoar is difficult without thorough snowpack assessment. Buried surface hoar is notorious for propagating far cross-slope and being remotely triggered. 

    Slopes that are wind loaded and harbor buried weak layers will be most dangerous today.

    Remotely triggered avalanche from the adjacent ridgeline that failed 5 days ago on buried surface hoar. 

    Photo: Bridger-Teton Avalanche Center

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–2

    Around 18 inches of snow has fallen in the last 48 hours. West to southwest wind increased yesterday afternoon through the evening forming fresh slabs up to 2 feet deep. These will be sensitive to the weight of skiers and riders today. Expect to find deeper and more reactive slabs above 9,500’ where stronger wind loading occurred. Look for obvious signs of wind affected terrain such as large drifts, stiffened surfaces, or shooting cracks. Be aware that wind slabs have the potential to break deeper and step down to buried weak layers.

    Watch for shooting cracks or signs of wind loading on leeward terain today. 

    Photo: Bridger-Teton Avalanche Center

Avalanche Discussion

Storm Cycle

The storm over the last 72 hours has added 22” of snow with almost 2” of snow water equivalent onto weak layers with complex variability. This weak snow was formed during a month long dry period in January, and has been found on terrain sheltered from the sun and wind prior to the initial burial. The type of weak snow varies from thick layers of dry facets to dangerous preserved surface hoar. Knowing which slopes contain these weak layers is difficult without digging down to investigate. Digging a quick pit can provide valuable insight about the distribution of these weak layers. Expect these weak layers to be reactive today as they adjust to the recent load of snow. Plan your backcountry travels accordingly to avoid areas that could harbor these weak layers.

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