Avalanche forecast

Central Cascades

Central Oregon Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The chances of triggering an avalanche in wind deposited snow will increase on Friday as sustained westerly to southerly winds transport snow to north and east aspects near and above treeline. Tirggering an avalanche in the new snow stacking up at mid and lower elevations is possible in steep and unsupported terrain. Ease into steeper terrain and observe signs of windloading and unstable snow such as cracking, collapsing, wumphing, and signs of previous avalanches. If you have any uncertainty in the snowpack move to lower angle terrain under 30 degrees. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2

    Wind slabs will build through Thursday night and Friday. Wind will be moving snow to north and east facing slopes below ridge tops and other features that are conducive to collecting wind transported snow. As drifts become deeper, resulting avalanches can become larger. Ease into terrain by checking out the wind loading on lower angle slopes. Monitor the depth of wind slabs and look for signs of unstable snow.

    Watch for signs of blowing snow to indicate slopes are becoming loaded. 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 buried surface hoar 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.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    During the high pressure earlier in the weak, surface hoar grew on top of the snowpack. In some wind exposed areas it was degraded or destroyed, but in protected locations it stuck around and has been buried. A new weak layer has thus formed on slopes where the surface hoar was present as the new snow came in. On Thursday, there was not enough snow above the buried surface hoar to conduct stability tests or get a sense of where avalanches will release.

    The likelihood of triggering a storm slab on this weak layer depends on the distribution of it. What we have going for us right now is that resulting avalanches will not likely be large enough to bury a person on open slopes. If you are travelling on steep terrain over 30 degrees, judge carefully what is below you and the consequence of going for a ride. Watch for terrain traps such as gullies and narrow constrictions that will allow for avalanche debris to pile up deeper. On isolated terrain features a burial could become a reality.

    (12/8/2022)

    A new weak layer was formed as the surface hoar in some locations was covered with new snow. As of late Thursday, it was 4-6" below the surface. The weak layer will become deeper as new snow comes in Thursday night and Friday. 

    Photo: Aaron Hartz

Avalanche Discussion

Conditions can change quite a lot throughout the forecast zone. The Central Cascades zone covers terrain from just south of Tumalo, across the 3 Sisters and Broken Top, and all the way to Santiam Pass. Always evaluate changing conditions and keep an eye out for anomalies. 

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