Boletín de aludes

East Slopes Central

Northwest Avalanche Center
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Peligro de aludes

Wed
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
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Desactualizado: este boletín caducó 6 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Dangerous conditions continue as significant snowfall and wind have added a heavy load and stressed older layers of weak snow.  Stay far away from and well out from under large open slopes 35 degrees and steeper. Consider avoiding avalanche terrain at upper elevations where you can trigger very large and destructive avalanches that could break widely across slopes.

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2–3

    Recent snow and strong wind have made it likely to trigger avalanches 3ft to 4ft deep. Persistent slabs can propagate widely across terrain features and can result in very large and deadly avalanches. Stay well out from under any large open slopes steeper than 30 degrees, as they can be triggered from a long distance away or from below. Be alert to signs of instability such as shooting cracks, and whumphing collapses.

    Recent observations continue to indicate that large slab avalanches can release on a crust from mid-January. These have occurred mainly on Northwest to Southeast aspects above 5,500ft. The Salmon la Sac, Icicle, and other areas on the south and western edge of the zone have been favored for snowfall and now hold dangerous conditions. While slabs are thinner and the danger may be less elevated in the Wenatchee Mountains, the avalanches will be similar. When the snowpack is complex, it's easiest to keep your decisions simple and avoid avalanche terrain.

    (2/8/2021) A very large (D3) natural avalanche likely ran between Feb 6-7th on Sixtysix Hundred ridge in the Icicle drainage. 6,600ft, ENE. Photo: Matt Primomo

  • Wind Slabs

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

    Strong west winds transported the snow in open and wind-exposed terrain. Feel for wind stiffened or hollow sounding snow as you enter open terrain, and change aspects.  Any avalanche in the new snow could step down to deeper weaker layers and result in a very large and deadly avalanche above 5,000ft. Consider the terrain you're connected to and avoid steep, open wind loaded slopes. Stay alert to indicators of wind slab such as heavy snow drifting, shooting cracks and whumphing collapses.

    (2/1/2021) From White Pass on Monday: Example of a small wind slab avalanche stepping down to weaker deeper layers.

Avalanche Discussion

Preliminary avalanche incident information Monday February 8th, 2021: Two snow bike riders were caught and buried by a very large avalanche in the mountains west of Salmon la Sac Sno-Park along Cle Elum Lake. One snow biker was partially buried and was able to dig himself out. The other rider was fully buried and killed by the avalanche. The avalanche occurred on a north aspect at 4400 ft in the Knox Creek drainage. This terrain lies in NWAC’s East Central forecast zone. Avalanche classification: HS-AV-R3-D3-O. 

All of us at NWAC want to extend our condolences to family, friends and the local community following this tragic event.  

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Dangerous conditions have produced many very large avalanches and avalanche involvements over the past week including the following:

Widely propagating avalanches ran over the weekend on an east aspect of Sixtysix Hundred (6600ft) ridge in the Icicle drainage. We received second-hand reports of triggered avalanches in the Salmon La Sac drainage on Sunday. On Saturday, observers reported a D2 natural avalanche near Van Epps Pass and a D3 sized avalanche that resulted in a burial with no injuries near the Easton Sno-Park. Observers reported a natural D2 avalanche on an east aspect at 5,500ft west of Blewett Pass on Friday. On Thursday, a snowboarder was caught in a wind slab avalanche at Mission Ridge on a Northwest aspect in the Near Treeline elevation band. Luckily they escaped unharmed. An observer reported a number of large (up to D2.5) avalanches with the recent storm from February 1 or 2 near Holden Village. 

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources. Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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