Avalanche forecast

Southern Wallowas

Wallowa Avalanche Center
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Avalanche danger

Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Generally safe avalanche conditions exist across the southern zone 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. 

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Avalanche problems

  • Wind Slabs

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

    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 signs of potential unstable 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

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Wet loose avalanches may be human-triggered on steep >35 degree slopes in the PM with daytime warming and possibly due to rain in the late afternoon. This problem type will be most active below 6000' or at lower elevations with no overnight freeze. 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 Southern Wallowas should be especially careful traveling up steep canyon gullies and drainages in the afternoon as slopes take heat, become unstable, and potentially unleash a torrent of wet avalanche debris down upon you. The tricky thing about moving up steep drainages, say like above Cornucopia, is that you are consistently in the line of fire as the trails traverse along the bottom of these steep slopes. Avoid this problem by staying off and out from underneath steep > 35 degree slopes in the PM. If you must travel under suspect slopes, please spread out and go one-at-a-time. 

    (2/21/2024)

    West Aspect at 7200' on 2/21

    Photo: Wallowa Avalanche Center

Avalanche Discussion

The Southern Wallowas look to benefit from the SW flow coming in with the next storm system. By Tuesday morning, elevations in the Southern Wallowas above 7000' could see 7-10" of new snow. 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 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 6000' 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. 

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. 

 

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