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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Out of date — this forecast expired 3 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

Moving from high danger to considerable does not mean it is time to let your guard down. Large avalanches are still likely, especially in wind drifted snow on lee terrain features near and above treeline. Weak layers in old snow underneath the recent storm snow are capable of producing very large avalanches. Terrain choice is key and it will be a good day to stick to low angle slopes less than 30 degrees. 

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1.5–2.5

    We have a lot of soft snow on the ground and more snow coming in. The winds will be blasting out of the westerly direction and moving a lot of snow to lee terrain. I expect new wind slabs to continue building overnight and throughout the day on Thursday. With strong to extreme winds in the forecast, wind slabs may form in unusual places. Although this will primarily be a concern in the mid and upper elevations, be aware of where blowing snow is loading slopes in clearings and areas of dead trees in the below treeline elevations. Cracking in the surface slab is a good incicator that triggering a wind slab avalanche can happen. 

    Archive photo taken by Elliott Reed

    This is a good example of cracking in wind slab. 

     

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–3

    There are multiple persistent weak layers beneath the recent storm snow. Buried facets and buried surface hoar can be found 2-5' below the surface. Compression tests (and in some cases, deep tap tests) can help you to identify these layers in snow pits.

    Over the last several days, observers have experienced slope collapses and whumphs. 

    This is a tricky problem in a sense that as the persistent weak layers become deeper we will receive less feedback in the form of whuphs and collapses. They will be less likely to trigger, but it is not out of the question. The slab on top of these weak layers is substiantial and will result in a large to very large avalanche if triggered. 

    (1/9/2024)

    Persistent slab avalanche crown on a NE slope near treeline triggered on 01/09. The failure in the snowpack was on faceted snow underneath the new snow from the last weak. 

    Photo: Jonas Tarlen

  • Storm Slabs

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

    Existing storm slabs need another day before we write them off. The incoming snow will be on the light and cold side of spectrum and may not creat new storm slabs, but will add stress to the existing storm slabs. Use small test slopes to check how the storm slab reacts to the weight of a person. Hand sheer tests are useful to check on depth of storm slabs. Look for signs of cracking in the recent storm snow as an indication that storm slab avalanches are possible.

    Small dry loose avalanches will also be possible in the new incoming snow especially in steep terrain. 

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