Avalanche forecast

Central Cascades

Central Oregon Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Triggering avalanches will be possible in recently wind drifted snow on northerly, easterly, and south facing slopes near and above treeline. Avalanches are also possible in recent storm snow on all aspects and anwhere the wind has not scoured it away. Triggering avalanches on weak layers deep in the pack at mid and upper elevations are unlikely, but will be large and destructive if they  do occur; steep and unsupported slopes with shallow rocky areas as potential trigger points are places to consider avoiding.

Avalanche problems

  • Wind Slabs

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

    On Thursday, a wind slab avalanche was reported from the Tumal bowl (east aspect, near treeline). It was reported as skier triggered. Size was not reported, but judging from one of the photos submitted it may be in the D2 size range. It is possible this ran on the January 16th crust/weak snow combo layer underneath the recently wind deposited snow. There is no significant snowfall in the forecast overnight or on Friday, but there can still be wind blowing snow in places where the freezing rain did not affect the surface. Wind slabs stabalize with time, but we should give this problem more time before writing it off. Wind slabs on top of buried surface hoar or the Jan. 16 crust/weak snow combo may  propagate wider and run farther than what we usually see. Look for signs of cracking in wind drifted snow and recent avalanches as indicators of unstable snow. 

    (1/18/2024) Photo from public observer

    Wind slab avalanche in the Tumalo bowl (east facing, near treeline). Reported as skier triggered. 

  • Storm Slabs

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

    Several storm slab avalanches were reported on Thursday. A small (size D1, 6" crown ) storm slab was skier triggered on on a north facing slope below treeline at Tam McArthur rim. In the Todd Lake area, a small skier triggered storm slab in steep terrain was reported on a NE slope near treeline. 

     Storm slabs on top of buried surface hoar or the Jan. 16 crust/weak snow combo may propagate wider and run farther than what we usually see.  Look for signs of cracking in recent storm snow and recent avalanches as indicators of unstable snow.

    (1/18/2024) Photo from Public Observer.

    Small storm slab triggered on a NE aspect near treeline in the Todd Lake area.

  • Deep Persistent Slabs

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

    Weak layers formed formed earlier in the season are now down 140 - 200 cm (or deeper) below the surface. Multiple layers of faceted snow and buried surface hoar are now deep enough where the chance of us triggering an avalanche on these layers is unlikely but not impossible. An avalanche occurring on one of these deep layers would be very destructive. We probably won't get any feedback in the form of collapses or whumphs associated with this problem and with the exception of digging down through the entire snowpack, we may not know if it is under us or not. Increase your margin of safety by avoiding trigger points such as shallow rocky areas in steep terrain. 

Avalanche Discussion

Continue to be cautious of recently formed cornices at ridge tops hanging over lee slopes. New cornices can be fragile and break easily under the weight of a person. 

Avalanches were reported from multiple areas on Thursday. This is a good example of our typical storm problems. Wind slabs and storm slabs tend to be most likely during and just after a storm. These problems usually quiet down a day or two after the storm but in some cases may stick around longer if they have formed over pre-existing weak snow. On Friday, it will be useful to dig into the snow and check for prevalence of weak snow underneath recent storm snow and wind slabs. When in doubt about the stability, give these problems more time before committing to steep slopes. Keep an eye on terrain traps and consider the consequence of being caught in an avalanche. 

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