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 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

A big storm that produced big avalanches just ended in the West South and now the snowpack needs time to adjust. Steer clear of steep open slopes especially at mid and upper elevations where the wind drifted the snow deeper. Some avalanches could become very large and destructive.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    2–3

    This sizable storm, limited access, and downed weather stations have us flying a little blind. However, with all the new snow and very strong ridgetop winds, it’s not a far stretch to anticipate thick firm wind slabs at mid and upper elevation. As the storm clears, these hard slabs maybe just waiting on a trigger. Give them a wide berth. Steer around steep open wind-loaded slopes particularly below cornices and in larger alpine terrain. 

    On Friday Crystal Mt Ski Patrol triggered a very large avalanche in wind-loaded terrain that failed down into older snow layers. This huge slide broke trees and ran to near its historical runout zone. Slides like this should cause all of us to stop and think long and hard about the consequences of traveling in alpine terrain right now. Deep wind slabs breaking into older snow layers that produce very large avalanches is very scary. This is just one more reason to give the mountains time to adjust and stay out of similar terrain.

    (1/7/2022)

    This very large avalanche was triggered by explosives on 1/7. The very deep (4-6') and wide (500ft) failed on an old snow layer, grew very large (D4) and broke trees. HS-AE-R4-D4-O, NE, 6800. 

    Photo: Crystal Mt Ski Patrol

  • Storm Slabs

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

    This massive winter storm finally came to a close on Friday afternoon, and while a few snow showers may still add a couple of inches to the totals, the numbers are impressive. It’s hard to imagine all that new snow is suddenly stable.  While the new snow should be gaining strength, you may still trigger avalanches on very steep slopes, near convex rollovers, and at mid-elevations. These slabs are thickest above the rain-snow line (~5000’). At lower elevations, soft slabs will be smaller and shallower only involving snow above the newest crust.

    (1/4/2022)

    Example: Soft storm slabs failing within the new snow. This intentionally triggered avalanche broke 50-60 feet below the expected start zone at White Pass on Tuesday (1/4). [S 5300']

    Photo: Dallas Glass

Avalanche Discussion

This storm pointed the firehose at the West South zone for just over 48hrs. Paradise recorded 6.7” of precipitation (5-7’ of snow) since Jan 5. Other locations closer to the Cascade crest even received 3+ft of snow (3.16” precip at White Pass). Notable avalanches at Cyrstal Mt, Hwy 12, and Mt St Helens highlight the extent of this avalanche cycle. However. access and observations have been incredibly limited over the last two days. This has us very uncertain about the current conditions and state of the snowpack. Add to that the huge Crystal avalanches on older snow layers, and we’re left wondering what will happen next. As you step out into the mountains, choose trips that easily let you recognize, manage, and retreat from the hazards you encounter. 

With all the new snow, treewells and snow immersion suffocation (SIS) have us concerned. Make sure to keep your partners in sight.

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