Avalanche forecast

Central Cascades

Central Oregon Avalanche Center
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Avalanche danger

Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Avalanches were observed throughout the terrain on Thursday.  Heavy snowfall overnight means that the avalanche danger will remain elevated on Friday.  Wind Slab avalanches will be likely and could be large on slopes where the wind has blown the new snow.  Below treeline Storm Slab avalanches could be large enough to bury or injure a rider.  Avoid steep, unsupported terrain.

Avalanche problems

  • Wind Slabs

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

    Wind Slab avalanches were observed near treeline on Thursday at Tam Rim.  Don't be fooled if the wind is Light on Friday; Wind Slabs that were created on Thursday and Thursday night will remain unstable on Friday.  I would be suspiscious of any steep north or east slopes that are below ridgelines.  Wind Slabs can also exist along cross-loaded features.  Cross loading occurrs when the wind blows sideways across a slope depositing snow behind ridges, rocks, and lines of trees.

    As the wind swings to the south and southeast tomorrow it will be Light.  It may be strong enough in the alpine elevations to redistribute snow to the northwest.

  • Storm Slabs

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

    Storm Slabs existed throughout the terrain.  At Todd Ridge I could trigger small slabs on test slopes.  The vast majority of these slabs failed on weak layers within the storm snow.  I did experience a collapse and then remote trigger (see video).  This avalanche slid on a layer of 1mm poorly developed facets above the prominent rain crust.  This weak layer seemed pretty isolated (I couldn't find it elsewhere along Todd Ridge), and for the most part it shouldn't effect you risk management strategy.  I may increase my margin of safety just a bit by expecting more propogation than I otherwise might.

Avalanche Discussion

Thank you to the public for the observations today!

Storm totals on Thursday afternoon seem to be around 45 cm.  The vast majority of instabilities exist within this new storm snow.  On slopes that receive significant sunshine there is a sun crust from last Saturday buried in the upper snowpack (see picture).  In some hand shears I could find weak snow beneath this sun crust.  This crust does not exist on shadier slopes. 

Similarly I did trigger one avalanche that failed on small, poorly developed facets above the prominent rain crust.  At this point it appears this faceted layer is very isolated throughout the terrain.

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