Bulletin d’avalanche

Blues

Wallowa Avalanche Center
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Danger d’avalanche

Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 5 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

There is no substantial change in conditions from the last couple of days. The hazard is from wet avalanches during the late morning to afternoon thaw phase of the diurnal freeze-thaw cycle we are currently experiencing. The later in the day a rider lingers on slopes capable of producing avalanches the greater the likelihood avalanches will be produced. The observance of roller balls on the snow surface and wet/mushy ankle deep snow are classic signs that the snow is becoming unstable. When these signs of instability are observed it is time to get off and out from under slopes steeper than 35 degrees. 

Problèmes avalancheux

  • Wet Slabs

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

    Like the aforementioned wet loose avalanche problem mentioned above, the wet slab problem is a byproduct of heat and weakness associated with melting snow. As temperatures rise melt water is produced. This melt water percolates down into the snowpack decreasing the strength of a buried weak layer. The result is the weakening of a large slab of snow. If this process persists long enough a potentially destructive wet slab avalanche can occur. Avoid avalanche terrain during the thaw phase of today's thaw cycle. Avalanche terrain would be terrain steeper than 35 degrees. By late morning or early afternoon the snow recreationalist should be off of or out from under avalanche terrain.

  • Loose Wet

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

    We continue to be in a freeze- thaw weather pattern where the snow freezes at night and therefore gets firm and strong. During the day the effects of rising temperatures and solar radiation soften and melt the snow to the point where it becomes weak and unstable. Look for this thawing process to take place today resulting in the possibility of wet loose avalanche activity on slopes steeper than 35 degrees during the late morning/early afternoon thaw phase of today's freeze-thaw cycle. Avoid avalanche terrain during the thaw phase of the cycle today and tomorrow.

  • Cornices

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

    Cornices are affected by heat induced instability much like the rest of the snowpack. As temperatures rise and thawing takes place, cornices become weak and brake off. They can break naturally from stress of their own weight or they can break from the stress of the weight of a human. They tend to break further back from the edge than you might expect. When traveling ridgelines today stay well back from the slope edge unless you are certain you are not going out onto an overhanging cornice. Always give cornices a healthy dose of respect. This is especially important when we are experiencing temperatures above freezing.

    This large cornice was observed yesterday at Spout Springs in the Blues. An unsuspecting recreationalist could easily walk out onto this cornice causing it to break.

Avalanche Discussion

Another day of warm afternoon temperatures and weak/unstable afternoon snow. Once again, best practice in these conditions is to avoid avalanche terrain during the afternoon thaw phase of this weekend's  freeze-thaw cycle. That means getting off of and out from under avalanche terrain when you notice the snow getting soft and weak. I expect similar conditions for tomorrow.

Régions couvertes