Avalanche forecast

Elkhorns

Wallowa Avalanche Center
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Avalanche danger

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

The Elkhorn mountains were blanketed by 4"-6" of low density snow Tuesday and Wednesday. This light snow is perched upon a semi supportable crust and is sluffing off this crust on slopes steeper than 35 degrees. A large enough loose snow avalanche has the potential to knock a skier or snowboarder off his or her feet resulting in an unwanted avalanche ride. A less obvious but potentially more serious problem is the poor structure our snowpack is exhibiting in the form of persistent slabs that reside deeper in the snowpack. Avalanches that occur on these deeper persistent weak layers are less likely to occur but are larger in size and potentially more destructive.

 

Avalanche problems

  • Loose Dry

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1

    The Elkhorns received 4"-6" of new snow during the most recent Tuesday/Wednesday snow event. The low density snow arrived undisturbed by wind and is resting upon a melt freeze crust. This cohesionless snow will need a day or two to bond to the crust layer. The crust layer makes for an ideal bed surface for the new snow to slide on. While out on a tour today in the Northern Elkhorns I was able to trigger a dry loose snow avalanche (sluff) on any slope steeper than about 35 degrees. The sluffs I triggered were small and inconsequential. On a slope with significant steepness and vertical, it would be possible for one of these sluffs to entrain enough snow to carry a recreationalist into a dangerous terrain trap.

  • Persistent Slabs

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

    The Elkhorn mountains are still struggling with persistent and deep persistent slab problems. These persistent slab problems are the most pronounced in areas I observed where the snow pack was a meter or less in depth. Snow in these lower elevation / thin snowpack areas (around 7400') is structurally weak and faceted, especially at and near the ground. An ECT test performed at 7500' on a NW facing slope failed / propagated at the ground using a moderate amount of force (ectp20 95cm down just above the ground) . The weak layer was basal facets or facets near the ground. I dug another test pit on a steep NW facing slope at about 8000' . At this location the snow depth was 240 cm and my test columns failed using a hard amount of force. The shears were non planar (Q3) and no propagation was observed. Failure occurred approximately 8" from the surface at the uppermost crust layer. Though my column tests were unreactive in the deeper snow, I am  concerned about the poor structure I am still seeing  in the mid and lower snowpack. Know that recreating on slopes > 35 degrees is a risky proposition until these crust/facet layers go away. At this time, triggering an avalanche on one of these deeper weak layers is unlikely, but the consequences of this kind of avalanche could be severe. Have a look at the observation submitted by Mike Hatch on January 29th for details about what he saw in the snowpack.

  • Wind Slabs

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

    Light to moderate west winds are forecasted for today. Expect the formation of sensitive wind slabs on east facing terrain especially at or near ridgelines and in the alpine.

Avalanche Discussion

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