Boletín de aludes

Blues

Wallowa Avalanche Center
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Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 2 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Avoid recently wind-loaded slopes where you could still trigger a lingering slab of cohesive wind-packed snow.   Continue to use caution, especially in areas where the snowpack is thinner and cohesive snow sits 2-3 feet above the weak January facets.  Warming temperatures and mostly clear skies will increase the chances of triggering small wet loose avalanches in steep solar terrain this afternoon. 

This forecast is sponsored by Quickhatch Provisions. 

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    Dense snow from Tuesday was blown into sensitive drifts along ridgelines, under cornices, and on exposed mid-slope features.    In many places, this new and wind-blown snow sits above less dense snow and/or older wind-packed layers that could make an excellent bed surface.  In areas where you find weak January facets 2-3 feet from the surface, a new snow avalanche has the potential to step down into this older snow creating a larger avalanche.  

    You are most likely to find windslabs along exposed ridgelines, underneath cornices or on exposed mid-slope features.  Look for signs such as rippled snow texture and dune-like features.  If you experience shooting cracks or whumphing of the snowpack, you are getting a free clue to dial back your terrain choices.  

    (2/20/2025)

    Dune-like wind loaded feature.

    Photo: Caleb Merrill

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    2–3

    While becoming increasingly less likely, it is still not out of the question to trigger a deep and unsurvivable avalanche on the weak January facets that sit 3-4' below the snow surface.  Observers are finding mixed results in their snowpack tests, and in many places, the snowpack structure is missing a firmer bed surface layer below these facets for an avalanche to slide. 

    While the danger level has dropped to moderate, don't be mistaken- the consequences of triggering an avalanche on this weak layer remains significant.  Treat this problem as a "low-likelihood/high-consequence" possibility and evaluate consequential terrain on a slope-scale level.  

    The most likely place to trigger an avalanche on these weak January facets will be in areas that hold a shallower snowpack with a cohesive slab of snow above them.  In some protected areas in the region, Surface Hoar has been observed sitting above the January Facets.   This set up could be particularly sensitive. 

    Persistent slabs often resist showing their hand, and may or may not offer obvious signs of instability such as shooting cracks or collapsing of the snowpack.  Continue to use careful terrain and group management techniques: Only expose one person to a slope at a time, keep eyes on, and always regroup well clear of avalanche runouts.  

    This picture was submitted last night of a reported natural avalanche that was taken along the Anthony Lakes Highway at about 5600'.  It was reported to have failed on January Facets.  

    (2/20/2025)

    This natural avalanche was reported along the Anthony Lakes Highway at an elevation below 6,000.  It was reported to have failed on the January facets.  Photo: Logan Kerns

  • Loose Wet

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–1.5

    A rain on snow event occurred in the Northern Blues on Tuesday, which likely weakened the strength of the upper snowpack.  Today, warming temperatures and sunny skies will continue to soften and warm the snow surface this afternoon, allowing wet loose avalanches to be triggered on solar aspects in terrain steeper than 35 degrees.  Yesterday, observers in the Western Wallowas saw several wet loose avalanches in the mid-elevation band on Southwest aspects.  If you find yourself in snow that is unconsolidated, wet, and sloppy, avoid riding above terrain traps such as cliffs, gullies, and creeks- or just move to a shadier aspect where the riding will likely be more enjoyable.  

    D1 wet loose natural avalanches. 

    Photo: Caleb Merrill

Avalanche Discussion

What Happened? 

 5" of new snow was received in the Elkhorns on Tuesday accompanied by winds gusting into the 20's.    A close call over last weekend left some backcountry travelers dusting themselves off as a human-triggered avalanche was reported on Lee's shoulder above Slickrock.  This storm slab likely failed on a density change within the new snow.  Check out this recent observation from the Elkhorns.  

In the Blues on Tuesday,  5" of new snow fell at the High Ridge Snotel, and 6" of new snow with 1.2" of Snow Water Equivelent  at the MilkShakes snotel- this means rain-on snow.  

What's does it look like....and what is the likelihood? 

New snow and wind slab avalanches will likely be stabilizing further today.  The afternoon will bring increased chances of triggering a wet-loose avalanche in steep terrain (>35 degrees) on solar aspects.  

To re-emphasize the Persistent Slab problem, it is important to think about each slope individually.  Just because you see yellow on the danger scale, doesn't mean it's good to go.  If you get it wrong and are mid-slope when a persistent slab avalanche releases, the outcome will not look good.   Carefully evaluate avalanche prone slopes before committing to them by digging down to see what's below your feet.  If you find dense and cohesive slabs above the January facets combined with a firm sliding surface below the facets- Steer clear of steep slopes.  

As the sun pops out and temperatures increase, start thinking about wet loose avalanches.   If you are seeing rollerballs/pinwheels or sinking up to your ankles in wet sloppy snow, retreat to shadier aspects and avoid riding above terrain traps. Throughout the weekend, if we get the rain on snow that is forecasted, this problem will become much more real.  

What to do about it? 

Hand shears, as well as riding over or ski cutting small (inconsequential) test slopes will give you a lot of information today as to how the new snow is bonding to the old surfaces.   

You will find many long-time professionals in the area still sticking to slopes 30 degrees or less to manage the Persistent Slab problem.  Continue to dig down and investigate the structure of the snowpack.  If you find hard over soft with a firm sliding (bed) surface below, you have all the right ingredients for a slab avalanche.  

As the sun pops out and temperatures increase, start thinking about wet loose avalanches.   If you are seeing rollerballs/pinwheels or sinking up to your ankles in wet sloppy snow, retreat to shadier aspects and avoid riding above terrain traps. Throughout the weekend, if we get the rain on snow that is forecasted, this problem will become much more real.  

Use terrain to your advantage and manage your group well. 

You can't get caught up in an avalanche if you aren't in avalanche terrain.  Evaluate the terrain carefully, and if you decide to engage in avalanche terrain, manage your communication and your partners well.  Only expose one person at a time to avalanche-prone slopes, keep eyes on them, and regroup in areas that are well clear of the runout of an avalanche path.  

It's been great to see all of the recent observations.  Keep 'em coming.  Add value to your forecast.  Submit an observation here.  

 

 

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