Boletín de aludes

Flathead Range & Glacier NP

Flathead Avalanche Center
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Peligro de aludes

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

Lo esencial

If forecasted warm temperatures and rain occur this afternoon, dangerous avalanche conditions may develop. Dry snow becoming wet for the first time could initiate wet snow slides. The chance of triggering a large, destructive avalanche on a buried weak layer may increase. If you notice warming temperatures and rain, retreat to lower-angle terrain for a safer experience.

Problemas de aludes

  • Loose Wet

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

    If today's forecasted warm and rainy conditions materialize, previously dry snow in the mid and upper elevations may become wet, increasing the chance of wet snow avalanches. Slides could entrain substantial snow, travel far, and pack a punch. Low elevations have remained above freezing for most of the work week, where human-triggered slides remain possible.

    Monitor rainfall and warming temperatures. Snow falling from tree branches and rollerballs is a precursor to a wet slide. If your boards or machine is mired in mushy snow, you have worn out your welcome and need to seek out lower-angle terrain. Limit the time you spend above terrain traps and in long-running gullies where dense debris may make escaping difficult. Be aware of steep terrain above you, as wet debris can be destructive. 

    (1/24/2024)

    The two wet debris piles are old and the one closer occured today (1/24/24). 

    Photo: Cam Johnson

  • Persistent Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    2–3

    Over the past week, observers noted natural avalanches, audible collapses, and propagation in snowpit tests associated with weak layers buried 1-4 feet below the surface. This weak snow structure is found at all elevations and aspects but is most troublesome at mid and upper elevations.

    Today's warming temperatures and rain may increase the likelihood of natural and human-triggered slides, possibly resulting in large and destructive avalanches. Loose wet slides, especially from upper elevations, could initiate a larger, more dangerous, persistent slab. Signs of instability, such as collapsing or cracking, may not be apparent before the slope you are on slides.

    Terrain selection remains the most sure-fire way to deal with this unpredictable problem. Choose low-angle slopes free from overhead hazards to minimize uncertainty. If you desire steeper terrain, dig into the snowpack looking for faceted, “sugary” snow near a crust 1 to 4 feet below the surface.

    (1/25/2024) Recent slab avalanche in the central Whitefish Range.

Avalanche Discussion

An impressively warm and wet Atmospheric River moved into western Washington and Oregon yesterday, with over four inches of water expected in many locations. How much moisture makes it to the Flathead is a bit unknown due to a developing ridge of high pressure, which is partially blocking this wet air mass from impacting our area. There is a fair amount of uncertainty with today's forecast, but temperatures are expected to rise, and rainfall increase this afternoon. Rain may reach the middle elevations (5000 - 6500 feet) today, and wet, dry surface snow.  

If the forecast verifies, dangerous avalanche conditions may develop this afternoon. Despite recent warm weather, plenty of dry near-surface snow remains available to move downhill as wet loose slides. These slides can entrain substantial snow, adding to their mass and destructive capabilities. Debris from these slides could trigger a larger, more dangerous hard slab avalanche on buried weak layers. 

Temperatures continue to climb tonight and tomorrow, and rainfall increases. The avalanche danger will remain elevated throughout Sunday. Rain is forecast to reach the upper elevations, where plenty of dry snow remains. If today's forecasted avalanche hazard does not develop, we are confident these conditions will develop tomorrow. 

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