Avalanche forecast

Elkhorns

Wallowa 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Out of date — this forecast expired 3 years ago.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

It remains likely that you could trigger a large deadly avalanche failing on weak snow 2-4 feet deep.  Avoid riding slopes greater than 30 degrees, avoid riding above terrain traps, and stay out of avalanche runout zones.  The snowpack has been talking to us, and we should listen.  

This forecast is sponsored by Brooks Painting. 

Avalanche problems

  • Persistent Slabs

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

    The snowpack structure in the Elkhorns remains poor.  The last week has brought about 1.5" of Snow Water Equivelent.  This has not been enough weight to tip the balance on the weak snowpack structure with natural avalanche activity, but the snowpack is primed and waiting for a trigger. Don't let it be you!  Check out a recent observation from the Elkhorns here and here. There are well-developed, large-grained facets at the January 4th interface, and more junk in the trunk (weak sugar snow) near the ground.   This weak snow is found between 2-4 feet from the snow surface in deeper snowpack areas.   All of the snow since January 4th has consolidated into a dense slab and sits above weak snow with some decomposing crusts below the weak snow.  Remember what we need for a slab avalanche? Slab + Weak Layer + Bed Surface.   When we put that in terrain steep enough to slide and introduce a trigger, we get a slab avalanche.   

    If you want to avoid avalanches, you should stay off of slopes greater than 30 degrees, stay well clear of avalanche runout zones, and not ride above terrain traps.  Don't trust these facets until they are swimming in the river!  

     

  • Storm Slabs

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

    Recent snowfall over the last week has been accompanied by some large temperature swings.  This has created some layering within the snow in the upper snowpack.  Use small, inconsequential test slopes to test the reactivity of the new snow.  Step above the skintrack and see if you can break a slab onto the skintrack.  Use hand pits to isolate a foot x foot column and pull on the back of it with your arm.  If you are getting clean breaks within the upper two feet of the snowpack, a storm slab is still possible.  Triggering a storm slab avalanche could easily put enough weight on the snowpack that a deeper, more destructive persistent slab avalanche could subsequently occur.  

    Photo: Caleb Merrill

Avalanche Discussion

As the 4-5 foot slab continues to strengthen and become even more cohesive, the weak sugar snow will continue to be a real threat.  It's becoming less evident if you just look at the snow surface, as obvious signs of instability may not be present.  The cracking and whumphing (collapsing) that we observed last week has decreased, and the slab may be able to hold the weight of a rider until the slab thickness decreases somewhere in the terrain.   

Seeing tracks on a slope does not mean it is safe to ride.  Persistent slabs are notorious for allowing unsuspecting riders to lay numerous tracks without incident before one unlucky rider finds a thin spot in the snowpack, collapsing the weak layer and creating a large, destructive avalanche.  Common thin spots in the snow often develop around rocky steep rollovers, or where the wind has stripped snow from the up-wind (windward) sides of ridgelines. 

Now is not the time to push the terrain.  Patience is the name of the game with persistent slabs.  Read the forecast in its entirety, make a conservative travel plan that allows for wide terrain margins, use clear communication with your partners, listen to your gut, and speak up.  

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