Boletín de aludes

East 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
1 · Débil
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Desactualizado: este boletín caducó 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Extremely cold temperatures will keep avalanches possible in light, dry surface snow on steep slopes. Watch for signs of older wind drifts above treeline to alert you to the lingering chance of wind slab avalanches.  Bring plenty of warm clothes and watch for frostbite and other cold-weather injuries.

Problemas de aludes

  • Loose Dry

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    With cold temperatures and existing light snow, you can trigger loose avalanches on slopes 40 degrees and steeper. You may even see a few natural avalanches on steep, sunny slopes if skies clear for long enough. Be vigilant to watch for triggering these avalanches, and stop out from under slopes of concern. Terrain traps like cliffs, gullies, and trees can raise the consequences of avalanches that otherwise might not result in injury.

    We've received lots of recent, light snow, and the cold temperatures will continue to keep these avalanches a problem. Watch for weakening snow surfaces. We expect that avalanches could be larger at higher elevations. There's significant uncertainty above treeline, especially with the potential for recent wind transport. 

    (12/26/2021)

    A skier triggered a loose dry avalanche (D1) on a steep (40deg) slope. Dirty Face Mtn, WSW, 3500ft.

    Photo: Matt Primomo

Avalanche Discussion

On Sunday, an observer on the eastern end of the Highway 20 corridor found 10cm of new snow over another 50cm of settled snow that has accumulated since the 21st. They reported generally, stable conditions with potential for loose avalanches in surface snow. 

If you manage to climb to the highest elevations, you may find lingering wind slab structure from last week. Slabs from the main wind event, on the 23rd, should be unreactive. You may find other subtle drifting in isolated locations from lighter and more recent winds. There's lots of low-density snow that can easily be blown around.  While not an official problem, keep wind slab avalanches in mind above treeline. Be diligent about keeping warm and preventing cold injuries like frostbite. We expect unusually frigid temperatures. Fortunately, winds will be light. Expect deep snow, difficult trail-breaking, and tree well/ suffocation hazards. Keep your partners in voice and visual contact.

New snow has incrementally piled up since the winter solstice, with storm totals of over 2' in the Hwy 20 corridor.  At the interface that was buried around the solstice, observers reported finding surface hoar as well as a thin sun crust on steeper S-SW slopes.  Observers have reported that these layers generally haven't been problematic. The last widespread avalanche cycle occurred on Saturday, Dec 18th (up to size D2.5) in the Washington Pass area.  A crust buried in early December can now be found roughly 4-5 feet below the surface, especially on slopes near and above 6000 ft.  We haven't seen recent avalanche activity on this crust.  If you're in the mountains, you can contribute to the forecast by submitting an observation.

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