Avalanche forecast

Central Cascades

Central Oregon Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
1 · Low
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Highlights

On Saturday it will be likely to trigger an avalanche in wind deposited snow near and above treeline on northerly, east and southerly facing slopes. The size of avalanches will depend a lot on how much snow falls tomorrow. Be cautious in steep and committing terrain, and above terrain traps such as cliffs, trees, and other features that can increase the consequence of being caught in an avalanche. If you observe signs of unstable snow such as cracking or previous avalanches, or if you have uncertainty in the snowpack, increase your safety margin by staying on slopes less than 30 degrees steep.

Avalanche problems

  • Wind Slabs

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

    The southwest wind is expected to be sustained in the upper teens to low 20's mph and will easily move the new cold snow coming in. The weather models have some disagreement with how much snow will fall on Saturday, but probably in the 3-6" range. With the upper end of the snow forecast we could see new wind slabs becoming large in isolated terrain.  Use visual clues to identify where wind slabs have formed and are building below ridge tops, peaks, and around features that catch blowing snow from cross slope winds.

    Most wind slab avalanches will be small but isolated terrain features can accumulate enough blowing snow to produce large avalanches. Monitor the depth of wind deposited snow. As wind slabs become deeper, resulting avalanches can become larger.

    Utilize small test slopes and low angle terrain to monitor the wind slab. Watch for signs of unstable snow such as cracking in the surface snow and  previous avalanches. If you have uncertaintly in the snowpack, stick to lower angle options less than 30 degrees steep.

    Be aware of clearings and open slopes with sparse trees below treeline where the wind can move enough snow to build wind slabs on lee terrain features. 

Avalanche Discussion

On Thursday, March 2, there was an avalanche that resulted in a trauma related fatality on Black Crater. The avalanche was a wind slab in steep terrain, easterly aspect, near treeline.  COAC will be conducting a site survey and creating an accident report. More information will be provided in the near future. 

On Friday, a skier triggered wind slab (size D2, near treeline, easterly aspect, 40+ degree slope angle) was intentionally triggered in the near vacinity of the above mentioned location on Black Crater. See picture below.

With blowing snow cornices may be growing in isolated locations along ridgetops. Don't linger under cornices and be cautious when approaching ridge tops from behind if you cannot easily identify where cornices have formed. 

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