Boletín de aludes

West Slopes North

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

You can still trigger large avalanches in wind drifted snow at upper elevations. Warming temperatures will add uncertainty and raise concern for wet avalanches and cornice fall. Monitor changing conditions throughout the day, and avoid large open slopes 35 degrees and steeper with evidence of wind loading or wet surface snow.

Problemas de aludes

  • Wind Slabs

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

    Recent storm snow appears to be gaining strength but may still be reactive to human traffic on slopes greater than 35 degrees, especially in wind-loaded areas. Avalanches could be 6in to several feet thick. Pay attention as you transition into wind-affected terrain looking for textured snow surfaces and firm and hollow snow. With significant warming Monday, cornices will require extra caution. These unpredictable features could fail, acting as huge triggers on slopes below. On solar aspects, a melt-freeze crust buried Feb 25 may still be a good sliding surface for avalanches. On the aprons of steeper slopes or areas below gullies and cliffs, buried graupel was reported recently as well. With all the variability, be sure to evaluate the upper snowpack carefully before committing to steeper terrain. Use visual clues to identify and avoid large wind-loaded features at upper elevations. Recent avalanches, shooting cracks, and collapses should direct you to lower angled terrain. 

    (2/27/2021) A natural slab avalanche (D1) on a north aspect at 4600ft in Bagley Basin. The avalanche is 1ft deep and likely failed on Feb. 26 with a nearby track from Feb. 27. Photo: Adam U

  • Loose Wet

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

    Freezing levels are expected to rise to 5000ft by Monday afternoon. These warm conditions will create the potential for loose wet avalanches on all aspects, especially at lower elevations. Watch for changing conditions throughout the day as cold snow from recent storms starts to thaw. Rollerballs and pinwheels indicate snow surfaces are wet and weak and that loose avalanches could follow. Steer away from terrain traps like gullies or slopes above cliffs that magnify the consequences of even a small avalanche. Keep in mind that wet loose slides in motion could even trigger slab avalanches. Seek out lower angled and supported terrain to reduce your risk. 

    Example photo of pinwheels and rollerballs from rising freezing levels and sun a few days after a storm.

Avalanche Discussion

No new avalanches were reported Sunday. On Saturday, two small natural wind slab avalanches occurred in Bagley Basin, and a cornice fall in Canyon Creek triggered a large avalanche 1ft deep on the slope below (see media gallery). Widespread natural avalanche cycles occurred on February 22 and 25 to size D3+ including avalanches that hit Highway 20 just outside Newhalem. Several avalanches in the past week ran thousands of feet to valley bottoms and broke up to 10ft+ deep.

Snow and avalanche conditions are variable throughout the West North Zone. In some areas, recent storm snow appears to be stabilizing quickly, but recent very large natural avalanches continue to weigh heavily on our minds. Monday will bring a significant warm-up following a prolonged period of cool and stormy weather. Give cornices a wide berth, especially during conditions like this. Continue to exercise caution and gather plenty of information before venturing into steeper terrain.

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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