Bulletin d’avalanche

Central Cascades

Central Oregon Avalanche Center
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Danger d’avalanche

Sat
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Périmé — ce bulletin a expiré 3 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

Triggering avalanches in wind drifted snow will be possible on northern and eastern aspects near and above treeline. Observe where wind blown snow is accumulating and watch for signs of unstable snow such as cracking or previous avalanches. Evaluate wind loaded slopes carefully before dropping into steep terrain and when in doubt about snow stability hedge your bets by moving to lower angle terrain less than 30 degrees steep. 

Problèmes avalancheux

  • Wind Slabs

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

    Old wind slabs are now mostly non reactive. I did not see much blowing snow near treeline on Thursday, mostly because the new snow was so wet and sticky and not easily moved by the wind. As the temperature drops overnight the new snow will be lighter and more easily moved by the wind. New wind slabs will grow throughout the day. Wind can pile up snow 5 times deeper or more compared to the snow that has accumulated from the storm. Most wind slabs will be small, however some isolated pockets of terrain that catch a lot of blowing snow could produce large avalanches. Blowing snow is a good indicator of where wind loading is occuring. Look for a pillowy drifts or a wavy surface texture as clues to where wind slabs have formed. 

    Wind slabs may show up in places like clearings and areas with sparse trees even below treeline. Remember burned areas and slopes with dead trees can experience a big wind affect and get a lot of wind deposited snow. 

    Utilize small features or low angle terrain to evaluate the wind slab problem. Look for cracking in the surface snow. Anytime you observe cracking in wind drifted snow, or if you see signs of previous avalanches, these are good indicators that you can trigger an avalanche. 

    This problem can be avoided by sticking to the sheltered slopes where little wind effect has occured. 

  • Cornices

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

    There are some large cornices out there along the ridge tops. New blowing snow will add some extensions to existing cornices. Fresh cornices can be fragile,  break easily, and can trigger slides on the slope below. Be cautious when approaching ridge tops where cornices may be lurking over lee slopes. Stepping out onto a cornice could result in a break and a fall onto the slope below. 

  • Loose Wet

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

    This problem will be mostly related to the lowest elevation terrain in the foreast zone such as Santiam Pass. The temperature around Santiam Pass will get up to the mid 30's F before the temperature and snow level drops. Rain and/or warm temperatures can cause the surface snow to become wet and slushy and lack cohesion. As the surface snow becomes wet and mushy be cautious in steep terrain especially above terrain traps. Watch for roller balls and pinwheels as precursors the wet loose avalanches.

Régions couvertes