Bulletin d’avalanche

Central Cascades

Central Oregon Avalanche Center
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Danger d’avalanche

Sun
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Triggering avalanches in wind deposted snow will be possible near treeline and above treeline. Wet snow avalanches will be possible on slopes in the direct sun and especially at lowest elevations in the forecast zone midday where the temperature will rise into the mid 40's. Use timing and choice of slope aspect to minimize exposure to wet snow avalanches. Watch for signs of unstable snow such as cracking and previous avalanches and anytime you have doubts about the stability of the snow stick to slopes less than 30 degrees. 

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–1.5

    The sun will come out on Saturday and the solar influence this time of year starts to becomes more intense. Wet loose avalanches will be seen more in areas around rocks that heat up in the sun and/or at the lower elevations. The daytime high temperature in the Santiam Pass area will get into the mid 40's, and this is where we may see the bulk of the wet loose avalanche activity. Watch for the snow surface becoming wet and heavy, rollerballs and pinwheels as the precursors to wet snow avalanches. 

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    I am keeping wind slabs at all aspects. Existing wind slabs on north, east and southeast slopes are still possible to trigger. On Friday I observed the northeast wind consistenly moving snow throughout the day at ridge tops in the Sanitam Pass area. The wind is expected to continue out of the northeast has the potential to build wind slabs on lee westerly aspects. 

    Wind slab avalanches have been observed over the last few days. Most of them have been small (D1) avalanches. On Friday a size D2 avalanche was skier triggered (see picture). This failed on a melt freeze crust with weaker snow around it. Wind slabs on northerly facing slopes will have the chance to be large if they step down or fail on this layer. 

    Most wind slab avalanches will be small, but large avalanches are not out of the question. On northerly facing slopes, it will be good to find a safe place to dig down to old melt freeze crusts in the upper pack and look for the presence of weak snow around the crusts. Weak snow above or below old melt freeze crusts can contribute to wind slab avalanches propagating farther and going bigger. Isolated features that have collected more blowing snow will also have the potential for large avalanches. 

    Monitor the depth of wind slabs. Deeper wind deposits can lead to larger avalanches. Hand sheer tests and ski pole probing are good methods to check for depth of wind slab. Previous avalanches and cracking in wind deposited snow are indicators that wind slab avalanches can occur. Utilizing small safe test slopes are good ways to check for reactivity in the slab.

    (3/29/2024)

    Skier triggered wind slab avalanche that failed on an old melt freeze crust down 45 cm (18"). The slab propagated about 50' across. This was on a NNE slope near treeline on Friday. Size D2 (large). 

    Photo: Jonas Tarlen

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