Elkhorns

Avalanche problems

• 

  Persistent Slabs

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1–2.5

  There is approximately a foot or more of new snow near and above treeline that has fallen in the last 24 hours with another 2" - 5" forecasted to accumulate  today depending upon location. This new snowfall was and continues to be accompanied by west, west southwest, and west northwest winds strong enough to transport large amounts of snow onto leeward facing east, northeast, north, and possibly northwest facing slopes near and above treeline and at ridgelines. These deep and heavy parcels of wind deposited snow could be resting atop layers of surface hoar that formed earlier in the week and observed extensively throughout the Wallowa and Elkhorn mountains. Because this wind deposited snow is sitting atop and burying a persistent weak layer in many locations , we are labeling the problem a persistent slab problem. Wind slabs perched atop a persistent weak layer like  surface hoar can be extremely  sensitive to the weight of a human which will make them very easy to trigger today on steep leeward facing slopes at and above treeline. This double whammy combination of windslab formation burying surface hoar that has formed in the last week has created dangerous avalanche conditions. Cautious route finding and conservative decision making will be essential for recreationalists traveling through avalanche terrain today. Human triggered avalanches are likely today on terrain steeper than 30 degrees. Natural avalanches are possible as well so make it a point to stay out from under avalanche terrain. If you see natural avalanches on terrain near or similar to terrain you are considering, think about recreating on terrain less than 30 degrees in steepness. If you are seeing other red flags like shooting cracks projecting out in front of skis, or you hear and feel "whumpfs" , these red flags are telling you the snow you are traveling upon is unstable and could avalanche. Ideally, the best plan today is to avoid steep wind loaded slopes. After all, there is an abundance of great lower angle terrain below treeline that is holding great snow for your skiing ang riding pleasure.

  

• 

  Loose Dry

  N

  NE

  E

  SE

  S

  SW

  W

  NW

  • Alpine
  • Treeline
  • Below treeline

  Likelihood

  Likely

  Size

  1–2

  Yesterday afternoon I ski toured the Northern Elkhorns. There was about 8" - 10" of new snow that has accumulated since Monday, undisturbed by wind. These conditions existed between 7500' all the way up to the ridgeline at 8600' . I was able to trigger numerous small loose dry avalanches on safe test slopes steeper than 35 degrees. I think it will be likely that a skier or rider will be able to trigger a loose dry avalanche today on steep slopes that remain undisturbed by wind. Most likely locations would include steep wind sheltered areas below treeline, especially solar aspects that harbor  melt freeze crusts. These slick crusts that exist on south facing slopes and lower elevation terrain don't bond well to new snow therefore making them great sliding surfaces for avalanches to run on. Even though loose dry avalanches are generally considered less dangerous than slab avalanches, they are dangerous enough to carry a person into and through trees, rocks, and over cliff bands. A loose dry avalanche can also carry a rider into a gully where deep burial is possible. Consider the consequences before committing to that steep slope today.