Avalanche forecast

Central Cascades

Central Oregon Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Avalanche danger will rise throughout the day as more snow falls and the wind moves snow to lee features. Tiggering an avalanche in wind deposited snow will be likely near and above treeline primarily on north, east, and south facing slopes. Triggering an avalanche will be possible in the new snow near and below treeline. Be cautious on steep and committing slopes especially above terrain traps and anytime you have uncertainty in the snowpack, stick to slopes less than 30 degrees steep, 

Avalanche problems

  • Wind Slabs

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

    The west and southwest wind will be picking up overnight and into Thursday. I expect there will be a lot of blowing snow. New wind slabs will be building below ridge tops, peaks, and around features that catch blowing snow from cross slope winds.

    Look for the fat pillows of wind drifted snow and/or a wavy or ripply surface texture to indicate where wind slabs have formed. Blowing snow and new conrices are also good indicators of which slopes are becoming loaded. Use careful evaluation before committing to steep slopes where wind loading has occured. Monitor the depth of wind drifted snow; as it becomes deeper, resulting avalanches can become larger. 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. However just because you do not see those signs, it doesn't mean the problem is not there.

    This will be a day to keep an eye blowing snow and wind slabs forming  in clearings, burned areas, and places where there are sparse or dead trees even in places you typically think of as 'below treeline'.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    This problem will depend on how much snow comes in. Storm slabs will grow throughout the day. Montior the depth of new snow stacking up. Recently formed crusts or firm older snow can serve as a good reference point and can help you to measure the new snow depth accumulating. As new snow stacks up to 8" or more, be cautious in steep, convex, and unsupported terrain. Use small test slopes and rolls to look for cracking in the new storm snow as one indicator that the storm slab problem is present. 

Avalanche Discussion

Over the last few weeks, several large avalanches have been spotted on steep north and northeast facing slopes in the high alpine terrain (Broken Top and Mt. Washington). Be very cautious in isolated extreme terrain especially on shaded and rocky slopes. We are not currently tracking any persistent weak layers in the Central Cascades Zone, however anomalies can occur in this type of terrain.

Continue to keep a watchfull eye on cornices at ridge tops. Be cautious when approaching ridges from behind. With new snow and wind, cornices will be growing; watch for where blowing snow is moving over ridges as an indicator of where they may be building. Stepping out onto a cornice can result in a air drop onto the slope below. Cornice breaks can trigger avalanches on the slope below.

Remember, any avalanche large or small can have increased consequences where terrain traps come into play. Be cautious above steep slopes, cliffs, trees, and constrictions such as gully features. 

 

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