Bulletin d’avalanche

Northern Wallowas

Wallowa Avalanche Center
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Danger d’avalanche

Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
4 · Fort
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Points saillants

Natural avalanches are likely, and human-triggered avalanches are very likely today.  These avalanches will be large and destructive.  Avoid traveling on or near any slope >30 degrees.  

This forecast is sponsored by Eagle Cap Mountain Guides.  

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–2.5

    There's plenty of light fluffy snow available for transport from the recent snowfall.  Winds will redistribute this light snow and pack it into slabs which will be sensitive to the weight of a skier or rider.  If you observe shooting cracks or can feel upside-down snow (heavier on top, lighter below) you are looking at a wind slab.  Travel near and above the tree line will likely be very unpleasant today, as winds are forecasted in the mid 20's to 30's with stronger gusts.  

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–2.5

    We have been observing poor snowpack structure, which is the equivalent to building your house on a weak foundation.  Each time we add a load (new snow or wind-drifted snow) the weak snow buried below the surface is tested.  Due to the persistent nature of this avalanche problem, we will likely be dealing with this issue for a while.  Because of the uncertainty of what it will take to trigger an avalanche on this weak layer avoiding slopes >30 degrees is important.  Conservative route selection, limiting your exposure, and increasing your margins are all recommended.   

Avalanche Discussion

With moderate to strong winds in the forecast for the next 24 hours avalanche danger will increase.   Triggering a persistent slab could result in a large avalanche that could bury or kill you.  Although we are all excited about the new snow, keep in mind there are still many trees, stumps, fence posts, and rocks buried close to the snow surface that could ruin your day or your season.  If you trigger a wind slab, there's a good chance you could release the entire season snowpack to the ground.  

The last two days forecasters observed reactive buried surface hoar while traveling in the Southern Wallowas out of Halfway and the Western Wallowas out of the Catherine Creek SnoPark.  Surface hoar can be dangerous when buried, as it can be triggered from below steep terrain.  We have also found faceted (sugar snow) near the bottom of the snowpack from the snow that fell in early November (Nov. drought layer).  

Once these two players (surface hoar and facets) are buried in the snowpack our terrain mindset needs to shift to a more conservative approach.  

Régions couvertes