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
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

A search for good riding conditions may lead you to slopes shaded from the sun. In this terrain, avoid triggering a large slide failing deeper in the snowpack by sticking to lower-angled slopes, especially at upper elevations. At upper elevations, ride around thin slabs of wind-drifted snow. 

Problemas de aludes

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–3

    As you climb higher in elevation, be wary of steep, shaded slopes with a convex profile. In this terrain, you can still trigger avalanches that break on weak layers buried 1 to 2 feet below the surface. Slides can be triggered from above, below, or from adjacent slopes, similar to the triggered avalanche shown in the photograph.

    The most foolproof way to manage this problem is to avoid steep slopes on shaded aspects. However, if you choose to step out onto steeper slopes, be selective and thoughtful about which ones you do. Choosing planar slopes that don’t have a steep rollover can reduce your chances of triggering an avalanche. Choosing slopes with smooth, clean runouts can reduce the chances of trauma if caught. Positioning a partner in a safe location and riding one at a time can improve your odds if caught.

    (12/19/2024)

    The large debris pile shown in this photograph is a result of a remotely-triggered avalanche. This avalanche was triggered from above, and grew large enough to bury a person. This avalanche failed on a northeast aspect at upper elevations. 

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    Yesterday (Monday), we received a couple of inches of new snow with winds strong enough to transport snow into fresh slabs. Thin slabs of drifted snow exist downwind of ridges, saddles, and gullies. The rain/snow line crept up well into the middle elevation band, so I suspect these small slabs primarily exist above roughly 6500 feet. You can manage this problem by riding around dune-shaped drifts and avoid riding below corniced ridgelines.

    (12/20/2024)

    A small wind slab is visible just beneath a cornice near the summit of Elk Mountain. This slide likely failed during the intense wind event of 12/17-18. 

    Photo: Mark Dundas

Avalanche Discussion

The recent spell of warm weather is helping the snowpack gain strength, but we are not out of the woods yet. We expect triggering a slide that fails deeper in the snowpack is becoming more difficult, especially at middle elevations where temperatures have been near freezing for nearly a week. Warm temperatures help sinter and round weak grains, thus making them stronger. We are more concerned about upper elevations where temperatures have remained cool, slowing the strengthening process, and where most of the recent avalanche activity has occurred.

The last reported human-triggered avalanches occurred 4 days ago (observation, observation). Natural avalanche activity that likely failed on buried weak layers happened in the previous loading event (observation). These all occurred above 6500 feet. Outside of those large avalanches, signs of instability (whumpfing and shooting cracks) are sparse. 

Recent observations indicate the 12/7 persistent weak layer is better developed in some parts of the forecast region, such as the northern and central Whitefish Range, central Glacier National Park, and the east side of the Swan Range. Assume this variability exists within the area you're traveling. Nasty surprises are possible even when you don't feel any collapses or see any shooting cracks.

Freezing levels are forecast to rise to almost 7000 feet with a chance for sunshine. This will wet the new snow and cause it to rollerball with the possibility of some small loose wet slides in areas favored by recent snow. Although you will likely see signs of warming, I don’t expect cascading rollerballs to entrain enough snow to knock someone off their feet.

Downloaded the app yet? 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 doublecheck danger ratings and travel advice on the drive to the trailhead or in the backcountry. 

Want to start your New Year on the right foot? Sign up for a Partner Rescue Clinic for motorized Riders on January 4 . Check out our calendar for other upcoming events. 

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