Bollettino valanghe

Elkhorns

Wallowa Avalanche Center
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Pericolo valanghe

Fri
Alta quota
3 · Marcato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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Non aggiornato — questo bollettino è scaduto 5 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

New snow and wind will increase the chances of avalanches today.  Avoid leeward areas along ridgelines that receive wind blown snow.  Look for signs of instability such as shooting cracks, recent avalanches, or collapsing of the snowpack. If observing these signs, utilize terrain less than 35 degrees in which to recreate.  Where new snow falls on a crust, small but fast moving dry loose avalanches will be likely and could easily carry you into consequential terrain.  

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    3-5" of new snow is expected over the Elkhorn and Wallowa Mountains today.  Storm slabs will be possible at all elevations and aspects today as the new snow falls on a mostly strong snowpack.  Test for bonding of the new snow to the old snow surface through hand shears and small inconsequential test slopes.   In exposed terrain and along ridgelines, look for wind drifted snow that may be developing into sensitive slabs.  This snow may look rippled or pillowy and smooth.  Avoid these areas. 

    If there are localized areas that receive more than 6" of snow, there remains the possibility to have an avalanche step down a bit deeper into the snowpack and run on or below the January 6th layer that can be found 4-6" below the snow surface.  In the Western Wallowas and Elkhorns, this layer is a well defined rain crust.  In the Northern and Southern Wallowas, it is a much thiner crust layer that is almost hard to find.  

     

  • Loose Dry

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Dry loose avalanches are possible today in steep terrain sheltered from the wind where new snow will fall on a crust.  Use small test slopes to assess the sensitivity of this avalanche problem.  If reactive, avoid steep terrain above 35 degrees especially where it is above a consequential terrain trap such as a cliff or a gully.  

Avalanche Discussion

The snow in the forecast will increase riding quality throughout the forecast area.  We have been seeing a mostly strong and rightside up snowpack in most locations over the last week.  The surface of the snowpack is a mixed bag, but consists of mostly a temperature or sun crust on East through South through West aspects.  North aspects that are in protected areas have seen a weakening snow surface with small facets and localized pockets of larger surface hoar being reported throughout the last week.  

As the snow falls today, it will be important to test to see how well it is bonding to the variety of snow surfaces.  Hand pits will be a useful tool for this.  If the new snow is starting to gain cohesion and slides off of the old snow surface in a clean fashion, storm slab avalanches are more likely to occur.   Curious observers will also want to check out what is happening with the January 6th warming layer/rain crust.   As mentioned above, if localized areas in the Wallowas beat the forecast with snow amounts higher than 6", storm slabs may break below the snow surface and have the potential to run on or below the 1/6 layer.  

  • In the Elkhorns and the Western Wallowas the 1/6 Rain crust is either exposed at the surface or sits anywhere from 2-6" below wind packed or settled snow.  At upper elevations above 7,000 ft, this crust has been reported as a sandwich of several ice layers with weaker snow in between.  See an Elkhorns observation from last week here.   In lower elevation bands, this crust is about an 1/8th of an inch thick and test results have produced failures below the crust.  Check out my observation on the snowpack structure from the western wallowas here.  See a video and photos below. 
  • In the Northern and Southern Wallowas, an actual rain crust doesn't exist, but you may see a very thin temperature crust layer and/or notice a hardness change in the snowpack 3-5" below the surface.  

Please submit any observations from your travels in the mountains.  There is no observation too small.  Even one picture helps.  We rely on your eyes to help us paint a better picture of what is going on in our large forecast area. Thanks!  

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