Bulletin d’avalanche

Central Cascades

Central Oregon Avalanche Center
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Danger d’avalanche

Alpin
3 · Marqué
Limite forestière
3 · Marqué
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

Wind slabs will build through the night and continute to build on Friday around north, east, and southeast aspects. The cautious decision will be to avoid  wind loaded slopes over 30 degrees. Identify wind loaded slopes and use good travel strategy to avoid the problem.

Problèmes avalancheux

  • Wind Slabs

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

    The weather is throwing in the perfect condtions for creating new and reactive wind slabs. We have cold light snow on the ground and more snow coming in. This light snow will be easily moved by the wind. Wind speeds expected in the upper teens and low 20's mph will be ideal for moving snow. Wind drifted snow will settle into a slab that is stiffer than the layer below it, creating the ideal setup for a slab avalanche. In much of the terrain, avalanches will be small. Montior the depth of wind drifted snow as you move through lee terrain below ridge tops. As you observe increased depth of wind loaded snow, expect resulting avalanches to become larger. There are specific pockets of terrain out there that will be capable of producing a large avalanche.

    Ease into steeper terrain. Look for cornices and rough, wavy, or chalky surface texture to indicate where wind slabs have formed. If you encounter cracking in wind drifted snow, or observe recent avalanches, that is a good indication to stay off of slopes steeper than 30 degrees. 

  • Loose Dry

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

    Dry loose avalanches will be possible to trigger in steep terrain anywhere the snow is not wind affected. Most dry loose avalanches will be small, but the size will depend a lot on the terrain. Expect steep and constricted terrain to allow a little more snow to move and flush through the feature.

Avalanche Discussion

Overall, the central Oregon snowpack is in good shape. We have a right side up snowpack in wind sheltered terrain and no observed persistent weak layers. The game for Friday will involve using good terrain management around wind loaded slopes.

The new snow is relatively cold and right side up and I'm not expecting the new snow to exhibit storm slab properties on Friday. However, it is always good to monitor changing conditions. If the new snow begins to show increased cohesion and is sitting on top of lighter and weaker snow, adjust your decision making to account for the potential  of triggering a storm slab on steep, convex, and unsupported terrain features.

On Thursday a natural wind slab avalanche (size D1, 7" crown) was observed on a steep northeast slope near treeline. 

The snow depth is stacking up with 110 - 160 cm (3.5 -5') measured at mid elevations, but keep watching for those early season obstacles like rocks and logs.

Régions couvertes