Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

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

You might see wind slab or wet avalanches - or both - depending on where you go in the mountains. Give steep, sunny terrain some room if you see signs of instability like rollerballs and pinwheels or the snow starts feeling like a slushy.

Problemi valanghivi

  • Loose Wet

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

    Saturday should bring more consistent sunshine to the Cascades. Temperatures are not necessarily warm, but light winds won’t do much to keep the snow surface cool either. Below treeline terrain was mostly rained out this week so there shouldn't be much soft loose snow to react with warming. Consider a higher likelihood of wet avalanches if you find more than a few inches of new snow below treeline.

    Look for pinwheels or balls of snow rolling down the slope as telltale signs of warming. Small wet loose avalanches could be a sign larger ones are not far behind.

    (11/8/2022)

    Rollerballs and pinwheels are an indicator of the snow surface becoming moist. 

    Photo: Andy Harrington

  • Wind Slabs

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

    As the current crop of shallow wind slabs gains strength, the place where you can trigger one becomes more isolated. If you do trigger a slab avalanche it would likely be on a convex rollover, gully wall, or around a cliff or rocky outcropping. Even a small avalanche can have big consequences in terrain with cliffs, rocks, or other hazards in the runout.

    Tune into the pattern of wind loading by using scoured snow surfaces, cornice-like features, and changes in snow texture to figure out where wind slabs might lie in wait. A few inches of soft snow might hide signs of wind loading. Use small test slopes to get a read on how the new snow is reacting to your weight. Small hand pits can help guage how wind slabs are bonded to the layer below.

    Small skier triggered wind slab on the White Salmon Glacier in March 2022.

    Photo: Zach Bunch

Avalanche Discussion

Avalanche conditions differ across the various frontiers of West Central. Areas east and south have seen avalanche activity taper with storm and wind slabs becoming less reactive. Wet avalanches are also the primary concern in Snoqualmie and Stevens Pass.

It's a different story to the north where there was just more snow, more rain, more wind, and more avalanches in the last week. Most relevant is an unusual pattern of avalanche activity reported on February 8th (obs, obs). These avalanches were large, surprising, and quite dangerous.  One was triggered from low on the slope. They are not typical wind slabs but they occurred in obviously wind loaded terrain. No injuries were reported but in one of the avalanches the rider was buried with a hand exposed and promptly dug out. 

No avalanches like these were reported anywhere else on the west slopes. But there is a lot of big, alpine terrain in West Central that could hold a similar snowpack - a layer of facets and thin melt-freeze crust buried anywhere from 1-4' deep. You are most likely to find this setup in the farthest northern and eastern alpine areas of West Central.

Pits may or may not do much to help you gauge if the slope in front of you is good to go. If you head into steep, wind loaded terrain above treeline you might simply be assuming a bit more risk than usual.

 

 

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