Bulletin d’avalanche

East Slopes South

Northwest Avalanche Center
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Danger d’avalanche

Tue
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

Another wet and soggy day is in store for East South with warming temperatures and the potential for wet avalanches or small slabs in the recent snow. Small avalanches could step down to deeper layers and break widely across terrain. Rollerballs, cracking, or recent avalanches are signs to choose lower angle terrain. 

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1

    Warming temperatures and rain on the recent snow could produce small wet loose or wet slab avalanches in steep terrain. Wet avalanches often start from trees or rocks shedding snow onto slopes below, but you can also trigger them with your skis or snowmobile. With a few crusts and weaker interfaces in the upper snowpack, wet slabs may be possible as well. If it's raining on dry snow or snow becomes wet and heavy, consider moving to lower angle slopes. 

    There is potential for these small wet avalanches to step down to deeper weak layers, triggering a larger slab avalanche 2-4ft deep. Consider these consequences before riding on steep terrain with wet, heavy snow. 

    (12/14/2023)

    Wet loose avalanches often release from steep rocks and cliffs overhead.

    Photo: Katie Warren

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3

    Persistent slabs are a tricky problem, often leading to a false sense of security with no apparent signs of instability, such as collapses or shooting cracks. But then, an unlucky individual hits the wrong spot on a steep slope, and the whole slope fractures and slides. It may not even be the first skier or rider on the slope. Your best strategy is prolonged patience and conservative travel techniques. Give yourself wide safety margins around large open terrain and avoid steep slopes where a smaller avalanche could step down to these deeper weak layers.A rider in the Manastash Ridge area remotely triggered one of these persistent slab avalanches on Sunday. This is good confirmation that the problem extends into the East South zone. Very large avalanches in the adjacent West South and avalanches to the north (East Central) also make it a good bet this problem also exists here. Weak facets exist on and within several crust layers buried deep in the snowpack. These avalanches could now be 2-4ft deep and potentially unsurvivable. With a few inches of new snow or rain, small storm slabs or wet avalanches could step down to these layers, producing a very large avalanche.

    (1/20/2024)

    A rider remotely triggered this avalanche near Manastash Ridge on Sunday, January 21st. We suspect that it ran on the Solstice Crust, and similar avalanches are widespread in the more eastern areas of the Cascades. 

    Photo: Chris Ofsthun

Avalanche Discussion

More rain and high-elevation snow is on the way, and while there isn't much precipitation, you could find storm or wind slabs building at higher elevations during the day. Lee slopes below ridgelings or steep rollovers are likely areas to trigger these avalanches. Use kickturn tests, small test slopes, or hand pits to observe the bond to the old snow surface. If these produce cracking or fail easily, avalanches are more likely. Warming temperatures and rain on snow are something the east slopes of the Cascades haven't experienced for a while, and the snowpack is undergoing a big transition. As we step out into the mountains after these shifts, be prepared to make assessments as you travel, and don't be surprised to see strange or quickly changing conditions. Build wider margins into your travel plans to account for this, and pay attention to warning signs such as collapsing, shooting cracks, or recent avalanches. In addition to the avalanche on Manastash Ridge, multiple human-triggered avalanches have occurred near the Blewett Pass area over the past few days. These are failing on the Solstice Crust, and many have been remotely triggered from adjacent slopes. An NWAC forecaster at Crystal Mountain saw a suspiciously large avalanche in Morse Creek, very close to the border of East South. With avalanches and a lot of uncertainty, it's always a good default to more conservative terrain.

Régions couvertes