Boletín de aludes

East Slopes Central

Northwest Avalanche Center
Ver en el mapa

Peligro de aludes

Mon
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
Open full map
Desactualizado: este boletín caducó 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

On Sunday, very warm temperatures and sunny skies will create dangerous avalanche conditions at upper elevations. Avoid steep sun-exposed slopes, and be cautious of overhead hazards from wet snow sliding off rocks and cliffs. The warm temperatures may create the potential for wet avalanches even in shaded terrain. If you are sinking deeply into wet, heavy snow, move to lower angle terrain.

Problemas de aludes

  • Loose Wet

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

    Temperatures at many weather stations in East Central reached over 40 degrees on Saturday, and another warm and sunny day is in store for Sunday. While blustery winds on Saturday may have helped keep surfaces cool, decreasing winds and even warmer temperatures on Sunday will make wet loose avalanches likely. Cloudy skies overnight trap heat and may prevent snow surfaces from refreezing. There is still plenty of dry snow that is susceptible to warming, and danger may increase rapidly, especially on sun-exposed slopes. It will be best to avoid steep sunny slopes on Sunday. Thick crusts under the storm snow can act as a good bed surface for wet avalanches to run on. Windy conditions have created crusts, dense slabs, and scoured slopes in many locations. These stiffer surfaces may take more time to soften and develop wet loose avalanche conditions. Inversion conditions may develop, keeping lower elevations in eastern valleys colder and less susceptible to wet loose avalanche activity. There is significant variability throughout the terrain, so take time to observe the snow surfaces. If you see pinwheels or rollerballs and the snow feels wet and heavy, avoid steep terrain. You can also observe how wet snow reacts when you push on small test slopes. If the wet snow gathers momentum and entrains additional snow, you can trigger a wet loose avalanche. Steep rocks and cliffs in the sun are prime locations for wet loose avalanches to start, be aware of overhead hazards and terrain traps that can increase the consequences of being caught in even a small avalanche.In some locations, weak faceted snow exists above the Late January Crust. There is uncertainty on how this layer will react to warming temperatures. But it is possible that a wet loose avalanche could trigger a deeper and surprisingly large slab avalanche. 

    (12/21/2021)

    Pinwheels like this are an indication that wet loose avalanches may be possible. 

    Photo: Matt Primomo

Avalanche Discussion

Uncertainty and variable conditions are the themes in the East Central zone. Over the last week, storms have deposited 10-16 inches of snow over various surfaces, including weak faceted snow and strong melt-freeze crusts. Strong ridgeline winds have redistributed much of that new snow into dense slabs, scoured west aspects, and created stiff wind-board surfaces. Eastern portions of the zone received minimal new snow, and surfaces are icy crusts where travel remains challenging. As the weather transitions into an unseasonably warm and dry pattern, this variability will significantly affect the distribution of avalanche hazard throughout the zone and add uncertainty to the forecast. If you are getting out to enjoy the sunshine, approach terrain with an assessment mindset, investigate snowpack interfaces, look for red-flag signs of instability, and pay close attention to surfaces warming in the sun. On sheltered areas on north and east aspects, facets over a crust have been observed at mid-elevations beneath the storm snow from 1/30 - 2/1. This layer seemed inconsistent in distribution and may not exist in wind-exposed terrain. Avalanches triggered on these weak layers tend to break farther or wider than anticipated. Use extra caution in sheltered terrain near the crest on NW-NE aspects. There is uncertainty about the distribution and extent of this layer, but it is only 1-2ft deep, so you can dig down to identify these layers quickly as you move through the terrain. If you find weak, sugary snow over firm melt-freeze crust under a cohesive slab, you could trigger surprising avalanches on steep slopes. In areas where this layer was observed in the East Central Zone, the facets were generally small and unreactive. However, reports of collapsing on a similar layer in the Stevens Pass zone are notable, and it is important to track this interface as you enter new terrain.

Regiones cubiertas