Boletín de aludes

Flathead Range & Glacier NP

Flathead Avalanche Center
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Peligro de aludes

Wed
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

East and north winds will continue to drift new snow into firm slabs on leeward-facing aspects. Look for and steer around areas where you observe blowing snow and wind drifted features. In areas not affected by the wind, expect to manage loose dry sluffs in steep terrain. These will be mostly small in size but could be dangerous if they catch you above a consequential terrain feature.

Problemas de aludes

  • Wind Slabs

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

    North and east winds are forecast to continue blowing at speeds capable of transporting snow. On Monday, observers found stubborn slabs of drifted snow up to 3 feet thick and active wind loading. Meanwhile, in the same range, other folks experienced loose dry snow with minimal wind effect. This variability while require you to assess new snow hazards on the fly today. If you find yourself in an area where the wind is actively loading specific terrain features, or you observe evidence of drifted snow, switch aspects and seek out terrain sheltered from the wind. 

    (2/20/2022)

    Cracking and small slabs triggered around skis. A sign to keep slope angles low. 

    Photo: Sara Boilen

  • Loose Dry

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

    Anywhere from 6 to 16 inches of new snow fell on Sunday with many areas still untouched by wind. This snow is low density and will sluff easily in steep terrain. If your decisions take you into that kind of terrain today, manage your sluff with defensive riding strategies. Allow snow to move past you and avoid getting knocked off your feet or snowmachine above cliff bands or timbered slopes where a small slide can have large consequences.

    (2/16/2022)

    Small sluffs out of steep terrain features. 

    Photo: Cam Johnson

  • Persistent Slabs

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

    Surface hoar and facets buried 1-2 feet below the surface may still be affected by the weight of a rider or their snowmachine in locations where a supportable near-surface crust does not exist. Continued propagation in snowpit tests confirms we are not out of the woods quite yet. If you choose to recreate in terrain on the north half of the compass, select planar slopes free of convexities to minimize your chances of triggering a slide. Choose areas with clean runouts free of surface obstacles that may limit the extent of trauma and burial if you are unlucky enough to awaken this layer.

Avalanche Discussion

Snow accumulations from Sunday range from roughly 6 to 16 inches. Favored areas include the Flathead Range, Glacier National Park, and the Whitefish Range where 12 to 16 inches of new snow fell. The Swan Range saw the lower end of snow totals with roughly 6 to 8 inches. Winds have varied in speeds throughout the forecast region and within each range. This makes describing where the problem exists challenging. However, identifying the problem should be simple.

Observations from Monday help describe what problems you may find today. In the northern Swan Range, we found 6 to 8 inches of low-density snow. We observed a couple of loose dry sluffs and found minimal wind-affected snow. Here, the primary problem to manage was loose dry avalanches. Further south, near Six Mile and Broken Leg in the Swan Range, an observer reported seeing intense wind transport. Mt. Aeneas has clocked sustained speeds at 45 mph out of the east for the last 24 hours, likely creating hard wind slabs. Yet an observation in the northern Flathead Range found 12 to 14 inches of new snow with no evidence of wind drifted snow. They easily triggered small sluffs on steep slopes. Further south in the same range, an observer found widespread wind affected snow above roughly 5500 feet with slabs 2 to 3 feet thick. These differences within the zones highlight the variability in wind speeds and hazards you may experience today. 

Continue to pay attention to blowing snow and surface conditions throughout the day. Wind will continue to blow at speeds capable of transporting snow. The primary question is where? If you find dune-shaped features and textured surfaces, you’ve found a wind slab problem. On some slopes, the wind effects may be subtle - a slight stiffening of the snow surface. If new snow feels cohesionless and loose, then you found a loose dry problem. 

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