Boletín de aludes

East Slopes South

Northwest Avalanche Center
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Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Significant snowfall early in the week maintains the potential for large wet avalanches. Rollerballs and snow shedding off rocks and cliffs should persuade you to avoid sun-exposed slopes before the activity gauges more deeply. Winds continued to load upper elevation slopes where you may be able to trigger a stubborn wind drift on a steep rollover in the terrain.

Problemas de aludes

  • Loose Wet

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

    Partial sunshine and milder temperatures on Friday should destabilize up to 15" of recent snow that has fallen since Monday. Consider the depth to the first supportable crust you encounter with your pole or probe. If the depth is more than 6", a natural or human-triggered avalanche would be large enough to harm you. Expect crusts near the surface to break down to expose more dry snow to the impacts of warming. If you feel the sun's energy, the snow probably does as well. Navigate to cooler, shaded slopes as rollerballs foreshadow loose wet avalanches on slopes 35 degrees and steeper.

    Example: Human triggered loose wet avalanches on a steep sunny slope.

    Photo: Dallas Glass

  • Wind Slabs

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

    Larger slabs formed with easterly winds early in the week, but you might also find more recent wind transport from SSW winds. We think that 10-15" of  snow has fallen since Monday, creating the potential for large human-triggered avalanches at upper elevations. Sunshine Thursday afternoon may have helped neutralize some of these slabs on the southerly half of the compass, but expect these slabs to remain reactive on northerly aspects. You can also use quick hand pits to feel for stiffer snow layers over softer layers in wind-affected terrain. In alpine terrain, avoid steep slopes near ridges. Consider low angle slopes or wind-sheltered locations. Use hand pits and test slopes to evaluate any areas with more than 6" of wind-affected snow above the crust. If you see signs of instability such as shooting cracks or feel the snowpack collapse beneath you, move to more conservative terrain with slope angles less than 35 degrees.

    Example of wind scouring snow from windward slopes (the other side of the ridge) and transporting it onto leeward slopes.

Avalanche Discussion

Recent April storms favored the eastern slopes of the Cascades, but snowfall amounts and winds have trended downward since Thursday, indicating a gradual stabilizing trend. Observations are limited and with all the recent snow, your assessment will be critical before moving into larger, more committing terrain features. With a complex mix of wet and dry snow problems, stick to simple terrain and wind-sheltered areas; and avoid slopes receiving strong April sunshine.

Access into areas of the East South with a consistent snowpack has become challenging, and therefore direct observations from the zone are limited. However, recent snow has been piling up on more recent melt-freeze crusts from 4/18, and the 4/8 Crust is now 2-4 feet deep. Make snowpack observations as you travel and if you find conditions you did not anticipate, make conservative terrain choices. Some southern slopes that were recently snow-free up to 5700ft may now have over a foot of snow. Use extra caution in these lower elevations where obstacles may be lurking just under the new snow, and creek holes may be drifted over or hidden.

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