Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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In sintesi

We saw about 6 inches of snow in Wednesday's storm, and it's possible that you could trigger an avalanche in the new snow, especially in thicker wind-loaded areas. Avoid steep slopes where wind has formed larger, pillowed drifts. The sun will probably come out and wet loose avalanches could run on steep, south-facing slopes, which you should consider steering around when you notice rollerballs running coming down in these spots. 

Problemi valanghivi

  • Wind Slabs

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

    Wind slabs up to about a foot deep could exist on top of the MLK crust. In areas where the snow was redistributed by the wind and became stiffer, it's possible that you could trigger an avalanche, maybe running down to the crust. In the neighboring West North zone we have a photo of an avalanche that failed naturally during Wednesday's storm. It propagated far, and we suspect it may have failed on a buried persistent weak layer just above the crust. We may have a layer of concern above the crust in this zone too, present on upper elevation shady aspects in this zone. Right now there's probably around a foot of snow or less sitting over this layer. 

    We suspect the new snow will settle and gain strength relatively quickly. However, in wind-loaded locations, it is possible that you could trigger a large slab avalanche that could bury, injure or kill you. Search for thicker, wind-affected slabs to avoid, which you're most likely to find beneath ridgelines, around rocky outcroppings, on steep rollovers, and in gullies. If you see wind actively moving snow on a slope, pay attention to where it's landing and if it's on a steep slope, steer around it. Long, shooting cracks from your feet are indicators of weakness in the snow, in addition to whumphs, and it's best to avoid nearby steep slopes if you encounter these signs of instability. Slabs you trigger could fail as deep as the new snow layer, or possibly deeper depending on the size of the drift or any additional underlying weaknesses. When in doubt, steer around slopes greater than 35 degrees on Thursday, especially where wind-loaded. 

    (1/9/2023)

    Wind slabs like this could fail on steep slopes with a human trigger on Thursday. 

    Photo: Irene Henninger

  • Loose Wet

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

    We may actually see the sun on Thursday. Wet loose avalanches could run in the new snow layer. Wet avalanches could run as deep as the MLK crust, depending on how much sun and warming we get. You'll probably see indicators on these steep, south-facing slopes first, like rollerballs coming down. Snow might get sticky, or gloppy. When this starts happening, pay attention to where you currently are, and where you're going. You may need to start thinking about avoiding the steep south-facing slopes, or beneath those slopes as well, if an abundance of rollerballs are coming down, and continued warming may lead to natural wet loose avalanches. 

    Rollerballs like this are often indicators that the snow surface is becoming weak and wet loose avalanches may soon follow.  

    Photo: Robert Hahn

Avalanche Discussion

We still have a lot of uncertainty about conditions and avalanches as we enter this period of high pressure. There's been a surprising amount of warm/wet cycles with a bit of snow between to break them up. There are old, large debris piles now hidden under a foot or less of snow. Gaping holes from creeks or rocky areas are still a concern, in addition to low, variable snow cover at many elevations. Make sure you pay attention to this during your travels. 

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