Boletín de aludes

East Slopes Central

Northwest Avalanche Center
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Peligro de aludes

Tue
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Winds will taper off, and snowfall will trend towards light showers on Monday, but it may be possible to trigger avalanches in wind drifted snow near ridges. Consider sticking to wind-sheltered terrain or traveling on lower angle routes to gain ridge tops. In the eastern portion of the zone, challenging travel on icy surfaces will likely remain the most significant hazard.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–2

    In areas close to the crest, up to a foot of new snow with strong winds fell overnight on Saturday. Snow showers and light to moderate winds will continue through Monday. Newly formed winds slabs are likely overlying various surfaces such as slick crusts, windblown, or weak snow over the recent Valentine's Day Crust. Look for visual clues of wind-affected snow such as round pillowlike drifts, textured surface snow, and cornices. You can use your ski pole, probe, or hand to quickly dig and look at depths of new snow and wind slabs. Look for red-flag signs of instability such as shooting cracks, recent avalanches, or collapsing. These are signs you should stick to wind-sheltered or lower-angle terrain. 

    (12/8/2021) Long shooting cracks in freshly wind drifted snow

    Photo: Matt Primomo

Avalanche Discussion

Snow accumulations tapered quickly from west to east in the zone. Observers found up to 20 inches of snow in areas closer to the Crest and areas further east under 10 inches of snow was reported, with Mission Ridge only receiving a couple of inches. Overall it seems the new snow had bonded well with the underlying crusts, but there is still a lot of variability in surfaces throughout this large zone. Therefore, approach new terrain slowly with a conservative mindset and make observations as you travel. Quick hand pits are a great way to investigate shallowly buried interfaces. If the new snow slides easily off the underlying surfaces, or you can get shooting cracks on small test slopes, it is probably time to move to lower angle terrain. 

There may be extended sun breaks on Monday. As we get closer to the spring, the sun can dramatically affect the snow, and isolated wet loose avalanches are a possibility on very steep slopes in direct sunlight. Cold temperatures and some cloud cover will likely limit the extent of this problem, but if the snow feels wet and heavy or you start to see rollerballs, you may want to make your way to shadier or lower angle terrain. 

In eastern areas of the zone, challenging travel conditions on icy surfaces will be the main hazard. Observers have reported glazed over wind board and bulletproof surfaces on high, north-facing terrain. Sharp tools like crampons and an ice axe may be necessary for travel in some areas to prevent long uncontrollable slides. 

In some locations near the Crest, weak faceted snow may exist above or beneath crusts from late January/early February. Forecaster Irene Henninger found this weak structure near Holden about 5cm below the surface. Additional snow on top of this crust-facet combination or very slick crusts may create a persistent slab problem moving forward. Dig down, or document these layers while they're near the surface if you travel on shaded upper elevation terrain.

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