Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

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3 · Marcato
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2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

New snow and strong winds are creating deceptively dangerous avalanche conditions at upper elevations. It could be easy to trigger fresh wind slabs up to 2ft deep on drifted slopes, though they may start as shallow fluffy slides. With multiple potential weak layers in the upper snowpack, play it safe by sticking to lower angled slopes, especially if you find signs of instability like shooting cracks or hear whumphing. 

Problemi valanghivi

  • Wind Slabs

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

    Strong winds and new snow are expected to create instabilities even at lower elevations on Saturday. The potential size of avalanche will increase as you gain elevation though. So will the likelihood. The new snow may be surprisingly reactive, as they may form over weak snow on a crust. Slabs could be 8"-24" deep in favored locations, and have the potential to step down over 2ft deep. Any shallow slide could step down to a slightly deeper layer and become a larger and more destructive avalanche.  Use caution to evaluate steeper slopes, especially if you observe active wind loading, shooting cracks or hear whumphing collapses. Likely spots to initiate wind slabs are on open slopes exposed to the wind, near large rock outcroppings, at the top of convex rollers, and steep, sparsely treed slopes.

    Textured surfaces, deeper drifts, and cornice formations can also help you identify likely wind slab locations. However, in areas where you find more than 12" of new snow, expect more widespread slab development. 

    If you see this you have found some reactive wind slab.

Avalanche Discussion

We're expecting more snow near the crest and in the southern part of the zone like the Salmon la Sac, and less further north and out east at Mission Ridge. Winds will be strong everywhere, but the amount of new snow you find may have a direct influence on your local slope scale avalanche danger. New snow has been trickling in since the new year, and is adding up over a crust from 12/30. Surface hoar and/or faceted snow has been found above this crust, and has produced sudden and planar shears over the past week. 

The snowpack in the zone is made up of a number of potential weak layers and crusts, and the upper crust isn't the only one to consider. The Solstice crust is another layer that has produced large slab avalanches with control work at Mission Ridge on December 30th. Observers  reported whumphing collapses from the west side of Jolly Peak at 6,500ft on 1/3, and from 5,000ft in the Enchantments on the 28th. Though we haven't seen many avalanches on these layers yet, we just haven't had much new snow to react as a cohesive slab yet. This will probably change on Saturday. As slabs become more connected and we add more snow, these slightly deeper layers warrant more consideration.

The snow cover is still shallow, especially further east in the zone and at lower elevations. Expect to encounter exposed creeks, and shallowly buried logs and rocks in many areas. 

If you get out, let us know what you see by submitting a public observation!

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