Boletín de aludes

Whitefish Range

Flathead Avalanche Center
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Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Choose terrain where a slide won't send you through rocks and trees, over a cliff, or into a gully. Steer around dune shaped pillows of snow or move to an area that is sheltered from, or scoured by wind. Cracking around your feet or machine is a sign that wind-drifted snow can avalanche on steep slopes.

Problemas de aludes

  • Wind Slabs

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

    Southwest winds redistributed mid-week modest snowfall into thin slabs. Winds have tapered but may rise to the speed capable of transporting snow later today.  You can find drifted snow near ridgelines or prominent terrain features where the wind decelerates and deposits snow.

    Slabs will be more stubborn to trigger than the past couple of days. You can identify these features by denser snow which keeps you or your machine from sinking more than a few inches. Dune-shaped features or a scalloped surface indicate that the wind has been at work. 

    Windward terrain or areas sheltered from recent wind offer slopes without a wind slab problem. If you plan on riding steep leeward terrain, choose runouts free of surface obstacles which can magnify the consequences of a slide or terrain traps where the snow can pile up deep.  

     

    (2/7/2023)

    We observed three crowns that were likey wind slabs. These failed on a north facing aspect. One of the crowns is obscured by cloud cover. 

    Photo: Cam

Avalanche Discussion

Yesterday (Thursday), an observer scoped a recent glide avalanche along the crest of the Northern Swan Range. This avalanche failed naturally and was located directly adjacent to a glide crack that opened earlier this season. Riders reported many "brown frowns" early this season, possibly due to above-average autumn temperatures warming the ground surface before the season's first snowfall. Honestly, glide avalanches are a bit of a mystery. Fortunately, the Northern Rockies Mountain Science Center has been working to crack the case here in Glacier National Park.  

Here are some things we do know about Glide Avalanches:

  • Glide is a natural (and typically slow) process by which the entire snowpack slides over the ground surface.
  • Free water can lubricate the base of the snowpack and enhance glide. This can be meltwater or rain.
  • Smooth grassy surfaces or rock slabs are ideal terrains for forming glide cracks. They tend to open up on specific slopes year after year. 
  • Glide cracks are an indication that a glide avalanche is possible.
  • The timing of a glide avalanche is complicated: sometimes, they may occur immediately after a glide crack opens, and sometimes the glide crack will hang tight for the entire season. 

This recent glide avalanche is a reminder to beware of the brown frown. The best approach for glide cracks and avalanches is not to approach glide cracks and avalanches. Let us know if you spot any more glide cracks on the landscape.

Come one, come all! Flathead Avalanche Friends Fest, a four-day festival from Feb 8-11, has a full schedule with mini-clinics, a keynote speaker, après, and a Big-A$$ Raffle. A little something for everyone. We hope you can join us to celebrate our community, learn about snow, and support our safety mission. Learn more here.

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