Avalanche forecast

Central Cascades

Central Oregon Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

There is a high degree of variability across the Central Cascades zone. In some northerly and east facing areas, storm snow and wind transported snow have fallen on weak faceted snow and/or surface hoar. In other areas, wind slabs and storm slabs will be stubborn and unlikely to trigger.  Avalanche activity picked up on Thursday in the Tam Rim area, while avalanche problems trended toward stubborn on the southern end of the zone. This is reason enough to dig into the snow and look for weak snow below the recent storm layer before dropping into any committing lines. Watch for recently triggered avalanches, cracking in the surface snow, and slope collapses as signs of an unstable snowpack.  Remember, that if you ever have any doubt about the stability of the snow, adjust your terrain choice to slopes less than 30 degrees steep. 

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Avalanche problems

  • Wind Slabs

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

    Wind slab avalanches will be most likely where slabs have built up on weak near surface facets that developed prior to the start of the latest storm. In the right terrain, wind slabs will have the ability to propagate faster and further than what we typically see. Wind slabs will be of greatest concern in shaded and cold N and NE facing terrain. On some slopes wind slabs will be stubborn and non-reactive. Wind slabs form in specifc places and are typically below ridge tops, high points, and around features that catch blowing snow.

  • Storm Slabs

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

    With 12" of new snow in the last two days, storm slabs could be large enough to do some harm. In areas where the storm snow has fallen on cold shaded snow, the likelilhood of triggering a storm slab will be much greater. Storm slabs on weak fadeted snow may propagate further than what we typically see.

    Observations from the southern end of the forecast zone, suggest the storm slabs are stubborn and are unlikely to trigger.

Avalanche Discussion

I'm holding off on calling the current avalanche problems a 'persistent slab' but that could change in the coming days as we find out if the weak faceted snow will abate or stick around.

The danger ratings and likelihoods represent the upper end of what we can expect and will not accurately represent the entire Central Cascades forecast zone. 

We have very little information from above treeline and therefore confidence in the forecast for that area is not high.

Multiple skier triggered slab avalanches were reported from Tam McArthur Rim on Thursday. Serval size D1 and one size D2 (large enough to bury, injure, or kill a person) avalanches were reported. No injuries were reported. 

Regions covered