Boletín de aludes

Flathead Range & Glacier NP

Flathead Avalanche Center
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Peligro de aludes

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

Lo esencial

It is becoming less likely for you to trigger an avalanche on steep, shaded slopes (NW, N, NE, E, SE). Slabs will be larger as you climb higher. Slopes that face south and southwest present a straight-forward option for safer riding in steep terrain.

Problemas de aludes

  • Persistent Slabs

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

    It has been four days since our last report of avalanches failing on a layer of surface hoar buried 8-16” deep. You are most likely to encounter this problem on shaded aspects at upper and mid- elevations. Shooting cracks or whumpfs are a clear sign that you have found this problem. You can also utilize hand pits to see if you can find a layer of preserved surface hoar or facets below 8+ inches of snow.

    You can manage this problem by:

    • Defaulting to lower-angled slopes, particularly on shaded aspects.
    • Choosing slopes that face south, where the problem does not exist.
    • Avoiding steep shady slopes where you find 8+ inches of snow on top of a weak layer.

    (12/9/2024) Crown profile on a northeast aspect at 6500 feet. This avalanche failed on buried surface hoar. Photo: Cameron Johnson

Avalanche Discussion

We’ve reined in the persistent slab problem a bit:

  • The problem has been removed from the Swan Range.
  • It is now listed as unlikely in the Flathead Range, and Glacier National Park.
  • It remains possible in the Whitefish Range, specifically the central and northern parts of the range.

Here’s the rationale:

  •  Since Monday (12/9) we received no further reports of recent avalanche activity on this layer.
  •  We’ve also received no further reports of obvious signs of instability, like shooting cracks or whumpfing collapses during that time.
  • Recent observations from the Swan, Central GNP, and John F Stevens Canyon all reported minimal signs of recent winds, limiting slab formation above the weak layer.
  • The observations from the Swan and Central GNP also reported a thin crust from rain during the12/7 storm.  Rain likely destroyed any surface hoar up to roughly 7000 feet in these areas.

Uncertainty is highest in the Whitefish Range and along the Flathead Range due to a lack of observations in those areas.  I would approach those zones with an assessment mindset today.  You can simplify things - or increase your safety margins - by defaulting to solar aspects (where weak layers are less problematic) or less steep terrain.

Did you hear about the app? You can now access our region's forecasts, observations, and weather data directly from the Avy App (IOS; Android). Many features are accessible offline, so you can win debates about the avalanche problems right in the backcountry or submit an obs while driving home. 

Are you looking for avalanche education opportunities? Check out our calendar for upcoming events. There is a Ladies Partner Rescue Clinic tomorrow December 14th. Next week, there is an Avalanche Awareness Class at Bias Brewing on Monday, December 16th.

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