Avalanche forecast

Central Cascades

Central Oregon Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
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Out of date — this forecast expired 4 years ago.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

There were several unusually large avalanches as this last storm tapered off Friday night and Saturday.  While the bulk of avalanche activity is likely behind us, it may still be possible to trigger an avalanche on Monday.  A layer of buried surface hoar has been mostly unreactive, but explains the unusually large propogation we've been seeing, and may result in avalanches on very isolated slopes.

Avalanche problems

  • Persistent Slabs

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

    Triggering an avalanche on the Dec. 8th surface hoar layer is unlikely.  Snowpack tests have showed this layer to be unreactive.  None the less, the size (propogation) of recent avalanches likely means that this weak layer was a contributing factor.  Given this uncertainty and the potentially large size of these avalanches, I have been hesitant to ski steep, unsupported slopes, or runs where terrain traps exist.

    During the next few days, if we see a cessation in avalanche activity, we can likely eliminate this problem from our list.

  • Wind Slabs

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

    Today the wind was Light.  Increasing winds overnight from the NorthWest will build wind slabs on lee slopes.  I expect Wind Slabs at treeline will be relatively small, and the potential for more dangerous Wind Slabs will exist in the alpine, or on slopes with a particularly large fetch.  Also be cognizant that even smaller Wind Slabs could step down to the buried surface hoar layer.

Avalanche Discussion

We have about 150 cm on the ground.  The storm that wrapped up on Saturday deposited 40-50 cm of new snow.  Much of this forecast has discussed the Dec. 8 surface hoar beneath this most recent snow.  There is a fair bit of uncertainty regarding this layer which seems mostly unreactive, but could produce avalanches on isolated slopes.

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