Bulletin d’avalanche

Central Cascades

Central Oregon Avalanche Center
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Danger d’avalanche

Fri
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
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Périmé — ce bulletin a expiré 4 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

The potential for triggering an avalanche will build throughout the day as snowfall increases and wind redistributes new snow to lee slopes.  Wind slabs will build throughout the day on north and east facing slopes near and above treeline. Evaluate the consequence of triggering an avalanche in wind deposited snow, especially above terrain traps such as gully features, rocks, cliffs, etc.

Problèmes avalancheux

  • Wind Slabs

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

    Wind slabs have the potential to build throughout the day and it will depend on how much snow actually falls and how much the wind is moving snow. Most lee slopes will not produce an avalanche large enough to bury a person, but watch for those isolated spots that seem to collect the blowing snow and where avalanches could become larger, especially by the late afternoon. 

    Watch for signs of blowing snow to indicate slopes are becoming loaded. Also look for visual clues on the snow surface, such as pillowy deposits and wavy or ripply surface texture, to let you know if previous wind transport has occured. Wind slabs forming over any of the existing surface hoar out there may run faster and wider than they typically would. Wind deposited snow can be many times deeper than the snow the storm has dropped out of the sky.

Avalanche Discussion

On Tuesday and Wednesday, the COAC field team observed widespread surface hoar formation near treeline and below treeline. Surface hoar is a fragile crystal type that grows directly on the surface of the snowpack. It is not a problem until it becomes buried by new snow and becomes a weak layer in the snowpack. With incoming snow in the forecast it is likely that some areas will get buried surface hoar but we won't know the extent until we can check it out after the snow falls. On Thursday, I don't expect the snow fall totals to be enough to produce storm slabs that will have a lot of consequence. However, don't be surprised to see new snow releasing in steep and unsupported terrain if it has fallen on surface hoar.

Régions couvertes