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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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Use caution in mid and upper elevation terrain where wind transported new snow forms unstable slabs. Keep tabs on the wind loading pattern in the terrain you travel and bypass steep, freshly loaded slopes. 

Problemi valanghivi

  • Wind Slabs

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

    A new crop of wind slab could form with gusty winds and light snowfall Friday night and Saturday. Though dense, wet new snow at treeline could limit wind slab development, look for drier snow and more reactive slabs as you gain elevation. 

    Pay attention to the pattern of wind loading by using scoured snow surfaces, cornice-like features, and changes in snow texture to suss out where wind slabs could be hiding. Blowing snow might just show you exactly which slopes are loading up. Evaluate the bond of wind slabs before committing to steep terrain - or just steer around steep wind loaded slopes to reduce the likelihood of triggering an avalanche.

     

     

    (1/5/2023)

    Obvious signs that the wind has been a player at Snoqualmie Pass were in your face no matter where you looked on 1/5.

    Photo: Ian Nicholson

Avalanche Discussion

Wet avalanche activity could be a factor on Saturday with snow levels hovering just below treeline. Pay attention to slopes overhead and look for signs of instability like pinwheels, rollerballs, or snow shedding from trees and rocks. Don’t linger directly under steep slopes if you start seeing any of the above.

Friday was pretty quiet on the west slopes as a weak, warm storm made its exit. Most areas from the Moutain Loop to Snoqualmie Pass picked up about 0.5” of precip as a mixture of rain and snow near treeline. Heather Meadows in West North ended up with 1.5” of H2O with the majority as rain and 3-4” of new snow at 4500-5000’. Strong winds with gusts to the low 50’s were recorded and wind affected snow surfaces are everywhere. 

Reported avalanche activity included a large, naturally triggered slab avalanche in the Baker Backcountry. It likely occurred early Friday morning (judging by the bit of new snow over the debris). It appears to be triggered by sluff or cornice fall from above. A few small wet avalanches were reported in the same area as well. To the south recent wind loading was also the main driver of avalanche activity with natural wind slab avalanches to D1.5.

There is currently 1-3’ of snow over the rain crust buried in late December. The upper snowpack is reported as well bonded with no layers of concern.  Instability has been limited to the most recent new snow and wind slab layers.

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