Boletín de aludes

Elkhorns

Wallowa Avalanche Center
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Peligro de aludes

Alta montaña
2 · Moderado
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Generally safe avalanche conditions exist in the Northern Wallowa and Elkhorn zones today. However, small wet loose avalanches are possible on steep > 35 degree slopes at lower elevations. Avoid steep gullies and soggy slopes in the PM. If you head to the top of the peaks, or into more complex terrain in the alpine, you may be able to find an unstable wind-loaded pocket. 

This forecast is sponsored by Outlaw Motorsports.

Problemas de aludes

  • Wind Slabs

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

    Increasing SW winds overnight and through the day will build pockets of unstable wind slab in the alpine. Overnight winds have been strong enough to move snow and load leeward slopes.  Reactive wind slabs are most likely on slopes facing NW-N-NE.  The effects of recent wind-loading may present as smooth hard pillows lurking below ridgelines or sub-ridges mid-slope, as cornices hanging imposingly over steep slopes, or if settled powder snow gives way to stiff punchy windboard. These are all the signs of potential wind slab. Look for and avoid steep slopes (>35 degrees) with large overhanging cornices, smooth textured wind pillows, and/or deposition zones with convex rollovers. 

     

  • Loose Wet

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

    Lack of a hard freeze overnight and the possibility of late afternoon rain at elevations below 6500' today will spike this problem type in the afternoon hours. Wet loose avalanches may be human-triggered on steep >35 degree slopes in the PM. Potential warning signs of wet loose activity include rollerballs and pinwheels cartwheeling down the slope, sinking up to your boot tops in wet snow, or getting your sled bogged down in a soupy moist mess. Recreationists in the two zones should be especially careful traveling up steep canyon gullies and drainages in the afternoon as steep slopes take heat or rain, become unstable, and potentially unleash a torrent of wet avalanche debris down upon you. 

    (2/21/2024)

    West Aspect at 7200' on 2/21

    Photo: Wallowa Avalanche Center

Avalanche Discussion

Our area mountains are set to be impacted by a significant storm system later today through Monday. By Tuesday morning, elevations in the Northern Wallowas above 7000' could see 6-8" of new snow and the Northern Elkhorns could see 10-12". Most of this precip will arrive in the early hours of Monday and continue through the day. The passage of the cold front on Monday will bring snow levels down to valley bottoms by 10am. The new snow will not bond well to the existing weak snow surfaces. This increases the likelihood of a storm slab problem developing on Monday into Tuesday where storm totals approach 10" or more. 

The lack of a hard freeze below 6000' overnight will keep the wet loose avalanche problem alive at lower elevations.  Additionally, elevations below 6500' may see rain on snow this afternoon. Rain on snow can rapidly increase instability. Wet loose avalanches or sluffs can carry you to places you don't want to be. Look for rollerballs and pinwheels as visual clues of wet loose avalanches. If you see these signs or start sinking into the wet snow seek lower-angle slopes or slopes without terrain traps in case you take a ride. FYI - there is still cold fluffy snow on northerly slopes at mid to upper elevations.

Increasing SW winds overnight and through today will build pockets of unstable wind slab in the alpine. Wind slabs are most likely on slopes facing NW-N-NE.  The effects of recent wind-loading may present as smooth hard pillows lurking below ridgelines or sub-ridges mid-slope, as cornices hanging imposingly over steep slopes, or if settled powder snow gives way to stiff punchy windboard. These are all the signs of potential wind slab. The warm temperatures compounded by the lack of significant new snow or wind are helping the wind slabs stabilize. However, danger may lurk in isolated pockets. Look for and avoid steep slopes (>35 degrees) with large overhanging cornices, smooth textured wind pillows, and/or deposition zones with convex rollovers. 

This is the time of year when extra caution should be given to overhanging cornices. As temperatures rise and the sun's power grows more intense cornice fall becomes an elevated hazard. Give cornice edges wide berth, and when traveling on ridges, always stay on the windward side where signs of terra firma exist - a tree, a rock, - something to let you know your not dangling in space and tempting fate. 

For future reference: Relatively calm conditions for several days combined with clear cold nights have produced some amazingly large surface hoar crystals on W-N-E aspects well up into the alpine. As we start to get snow later today through Monday, this buried layer of surface hoar could become an avalanche problem. When out touring today pay attention to where you are seeing significant surface hoar formation and tuck that little tidbit in your memory bank for future retrieval. 

The persistent slab problem is showing strong signs of being unreactive. The layers of concern are now capped by dense snow and multiple strong crusts. While it is unlikely you could trigger one of these slides, it is not impossible. Avoid shallow areas of the snowpack (< 1m/3ft) and trigger points- rocks, scoured areas, and steep convexities. 

Check out WAC professional observer, Sarah Jakober's recent report from the Northern Elkhorns. 

 

 

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