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 2 years ago. Vous consultez des conditions passées, pas le bulletin en cours.

Points saillants

On Friday, avalanches will be possible in wind-drifted snow on steep slopes at upper elevations. At lower elevations, in the trees and around the Santiam Pass, warm daytime temperatures and the chance of rain will make wet avalanches possible.  Evaluate the snow surface carefully and avoid steep, complex terrain if you're unsure about the snowpack stability. 

Problèmes avalancheux

  • Wind Slabs

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

    For the most part, our wind slab avalanche problem is trending toward small and stubborn. Thursday's light winds and mild weather gave recently-formed wind slabs a chance to bond to the snow underneath. Observers found that wind slabs were mostly shallow and hard to trigger. At Tam Rim, a large cornice broke and triggered a small wind slab avalanche on a steep slope below. 

    Nevertheless, triggering a wind slab avalanche large enough to bury or injure a rider will be possible in steep, open terrain and below likely trigger points like cornices, cliffs, and steep convexities. Evaluate the snowpack carefully if you're traveling in complex terrain up high. Measuring the depth of wind deposits, doing hand shears and quick pits, or probing the snow with your ski pole handle are good tools for gathering information as you move through terrain. 

  • Loose Wet

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

    On Thursday afternoon, I observed a few small, loose wet avalanches on very steep south-facing terrain below treeline, where the temperatures reached the mid-30s and the sun cooked the snow surface. At least one of these point releases was triggered by a "tree bomb" - a large blob of snow that dropped from the trees onto the snow surface. 

    With temperatures rising into the 40s at lower elevations on Friday, plus a chance of rain in the afternoon, small loose wet avalanches will be possible. Since the day will be mostly cloudy, but the air temperature will be quite warm, we could find loose wet avalanches beyond the typical sunny slopes. 

    If you're riding at lower elevations, such as the Santiam Pass, pay attention to the snow surface as the day warms. Snowballs and pinwheels that roll downhill are clues that the surface snow is losing cohesion. If you sink in past your ankles in slushy snow, move to lower angle terrain. Keep an eye on cornices, and give any large cornices plenty of room, especially if they begin to droop. 

    Finally, remember that even small avalanches can have worse consequences if you get pushed into a terrain trap like tightly spaces trees or over a cliff. 

Avalanche Discussion

There is still a layer of weak snow within the February storm snow (about the top 100 cm of the snowpack). This layer can be found about 40-50 cm below the snow surface, but it is gaining strength. Observers have not been finding any sudden results on this layer the last two days. 

I did not add Cornice Fall as an avalanche problem for Friday, but it's a good idea to give cornices a wide berth. Recently formed cornices could still be fragile, and warm temperatures (and rain) could make them more likely to break. 

Régions couvertes