Boletín de aludes

Flathead Range & Glacier NP

Flathead Avalanche Center
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Peligro de aludes

Fri
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 8 months ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Dangerous avalanche conditions exist. New and wind-drifted snow will form fresh slabs, making them ripe for human-triggering. Avalanches will be large enough to bury and injure a human. Stick to low-angle slopes and avoid traveling through the runouts of large avalanche paths.

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1.5–3

    Five to ten inches of new snow and continued wind loading will form sensitive slabs today. Some natural avalanches may be possible. Continuously reduce your exposure if snowfall rates exceed 1 inch per hour and avoid areas where the wind is transporting snow into thick, hard slabs. A dry slab triggered at upper elevations will gouge into wet snow further down, making a larger, more destructive avalanche.

    Cracking longer than your boards or machine is a sign that slabs are ripe for triggering. Slabs of wind-drifted snow will be hard, so give ridgelines a wide margin since hard slabs are notorious for breaking further back than expected. Today is not a good day to step out into steep terrain.

    (12/10/2025)

    A triggered slab avalanche on a test slope yesterday (Wednesday). This slab failed within the new snow. Slabs today will be thicker, especially in wind-drifted areas.

    Photo: Flathead Avalanche Center

  • Loose Wet

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

    Rain on snow and warm temperatures triggered a series of natural avalanches over the past few days. The rain line has steadily risen to about 7000 feet this morning. 

    Wet loose avalanches can occur on all aspects until the snowpack surface refreezes.  Minimize overhead hazard and stick to lower-angle slopes. Even a small point release can carry a large amount of wet snow downhill. Plan to manage this avalanche problem until you reach dry snow, which may be above 7000 feet. 

    Multiple wet loose slides are visible on slopes facing NW-W-SW-S. This peak is north of Lake McDonald.

    Photo: Mark Dundas

Avalanche Discussion

Although I expect most of the natural activity to be over, human-triggered avalanches will remain likely. The avalanche danger will increase the higher you climb. Travel advice is straightforward and simple today: avoid avalanche terrain altogether.

The precipitation forecast today will increase the avalanche danger in areas favored by new snow. The Flathead Range should pick up 5 to 10 inches of new snow, whereas other ranges in the forecast area should see anywhere from 2 to 6 inches. Expect more sensitive and dangerous avalanche conditions if you see more than 6 inches of new snow pile up with sustained winds. Personally, my biggest concern today is a dry slab triggered up high that runs down into wet snow. These avalanches can run far distances and are pretty much unsurvivable. 

Thankfully, temperatures will drop throughout the day, helping refreeze the surface and lock up the snowpack. I’m not sure when this may occur, and until then, the wet snowpack is untrustworthy. For example, take a look at this photo Mark took of an avalanche that failed to the ground in the Apgars. This avalanche ran roughly 3000 feet to the valley bottom and took out the whole season's snowpack. Rain on snow makes big avalanches.

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