Boletín de aludes

West Slopes South

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

Storms continue to parade across the region with more precipitation maintaining dangerous avalanche conditions. If you travel above the rain-snow line, steer around open slopes greater than 35 degrees. At lower elevations, new rollerballs or piles of fan-shaped debris can serve as clues that the snow surface is becoming wet and unstable.

Problemas de aludes

  • Storm Slabs

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

    We’re expecting more snow in the West-South with oscillating snow levels and strong winds. This should lead to new storm snow instabilities. Avoid traveling on open slopes greater than 35 degrees. You’ll want to look at the layers above the latest interface (1/1) which should be marked by a rapid increase in resistance. Hand-pits, hand-shears, and small slope tests can help highlight which storm snow layers could fail. 

    If you travel in a location that receives less than 6” of new snow, focus on wind-affected areas. These wind-loaded locations could hold slabs thick enough to create a hazard. Travel around areas where you see smooth pillow-like drifts or anticipate wind loading occurred.

    (12/31/2020) This large avalanche outside of the White Pass ski area ran out into the flats below the path. Gunsight Bowl. NE-E 6300' HS-ACu-D2.5-R3-I

  • Loose Wet

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

    On Friday, 2 large loose wet avalanches hit the road to Paradise at Mt Rainier. While we expect most of the natural loose wet avalanche activity to have occurred during the initial rain event, more water will only maintain wet snow conditions. On longer slopes, some of these point release slides could entrain additional snow and become larger. If you see new rollerballs or fresh fan-shaped debris, steer around similar slopes. Even though loose wet avalanches appear slow and easy to manage, if they catch you, they could carry you through trees, off a cliff, or into a creek. 

    (1/1/2021) New rollerballs on the Valley Rd near Paradise, Mt Rainier National Park. Clues like this indicate the surface snow is becoming wet and unstable.

Avalanche Discussion

Mild weather New Year’s Day along with a little rain created wet heavy snow on the surface into the above treeline band. This should help recent storm layers gain strength and limit any additional avalanche activity to the most recent snow. One exception may be locations where the 12/29 interface holds buried surface hoar. Prior to the onset of our New Years’ storm cycle, surface hoar was observed at Paradise, White Pass, and to a lesser extent Crystal. One large explosive triggered avalanche at White Pass was confirmed to fail on these weak feathery grains. (E, 4500’) A second, widely propagating avalanche may have failed on a similar weak layer. (NE, 6300’). If avalanches fail on this layer of concern, they could propagate around terrain features and even pull snow from lower angled slopes. 

We’re now 4 days into a prolonged storm cycle. Snow continues to pile up at upper elevations. As storm totals grow, so does our uncertainty. We don’t suspect avalanches breaking into older snow, however, they may begin to entrain additional storm snow and grow large. Use caution if you travel near larger avalanche paths or venture into upper elevation terrain. 

I’d like to thank all of you for submitting your observation in 2020! As of today, we have had 96 observations from the West-South zone on our public site. Your observations help us create the best possible forecast. Keep it up in 2021!

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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