Bollettino valanghe

West Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Sat
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 2 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Avalanche danger remains low overall—except on slopes holding fresh, wind-drifted snow. Watch for and avoid travel on steep terrain with pillow-like drifts, firm slabs, or clear signs of instability such as shooting cracks or whumphing.

Problemi valanghivi

  • Wind Slabs

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

    The wind should be long done blowing by Valentine’s Day, but there will be plenty of stiff slabs out there for you and your sweetie to navigate around. Wind slabs typically bond quickly, but could still be easy to trigger where they formed over faceted snow, slick crust, or some other weak surface. Reactivity could vary from feature to feature so don’t assume that finding an unreactive wind slab on one slope means all the others will behave the same way.

    While most wind slabs you find should be small, some could be larger or possibly step down and trigger an avalanche that releases in deeper layers. Look out for stiff snow and wind textured surfaces as you gain elevation and change aspects. Simple tests can help you evaluate the bond of slabs to the layer below. Don’t ignore obvious signs of instability shooting cracks and whumphing.

    (12/12/2024)

    Wind scoured surfaces means there is probably some wind slab nearby. 

Avalanche Discussion

Observations were few on Thursday as many are waiting out the wind and banking on fresh snowfall late in the weekend. The biggest story from the west side of the Cascades was very strong to extreme winds and extensive snow transport in Snoqualmie Pass and West South.  Backcountry travelers found shooting cracks in normally wind sheltered terrain as strong winds reached down to valley bottom and ripped through the passes.  A little closer to home, large amounts of wind transported snow were observed on the highest reaches of Glacier Peak. One team in West North found fresh slabs while climbing into upper elevation terrain. Though slabs were reactive enough to warrant avoidance, they were shallow and pocket-y enough in distribution that it was possible to navigate around them. 

The wind has been doing its best to mess up the soft, dry snow we have enjoyed for over a week, but soft snow can still be found on sheltered and shaded slopes. Crust tops the surface on slopes facing the sun. Continued clear skies and cool temperatures have enabled faceting in the uppermost layers with surface hoar and faceted snow found topping the snowpack in sheltered areas.  It's safe to assume that many windward slopes had much of the weak snow at the surface scattered or destroyed by wind.

Buried weak layers that produced avalanches two weekends ago have trended more resistant in testing and less likely to propagate. Also, no human-triggered avalanches - that were suspected of releasing at either the 1/31 or 1/10 interfaces - have been reported since Sunday, February 2nd.  The layering in question can be found between 1.5-4' deep where the top layers of snow meet a crust or denser layer. We may see more action from these layer as fresh snowfall in the forecast adds additional load. 

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