Boletín de aludes

Flathead Range & Glacier NP

Flathead Avalanche Center
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Peligro de aludes

Sun
Alta montaña
1 · Débil
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Enjoy today's sunshine and generally stable conditions before moisture returns to our area Sunday afternoon. Continue practicing safe travel techniques of just one rider on a slope at a time. Minimize your chances of triggering a slide on a deeply buried weak layer by choosing terrain free of rocks and convexities while keeping an eye out for isolated drifts of snow.

Problemas de aludes

  • Deep Persistent Slabs

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

    Triggering a slide on a deeply buried weak layer remains a possibility. Areas most susceptible to triggering are where the snowpack is either shallow, such as wind-scoured slopes and terrain peppered with rocks or has a convex slope shape. The only way to know if the slope you are on harbors these layers is to dig to the ground. Even then, snowpack tests don't always give clear signals. We recommend using terrain to navigate this problem: Choose planar slopes free of convexities, avoid rocky areas where weak snow develops, and steer around thin wind-scoured areas in favor of slopes holding a deeper snowpack.

    (1/27/2022)

    Weak layers near the surface and near the ground did not show concerning test results in a profile at 7200 feet on a west aspect in Tranquil Basin.

    Photo: Clancy Nelson

Avalanche Discussion

Hopefully, today will be our last full day of sunshine and dry conditions before Pacific moisture enters the area late Sunday into Monday. We have enjoyed generally LOW avalanche danger for the past two weeks, except for a brief period during and following our last snowfall on Thursday, January 20. Riders have enjoyed stepping out into larger terrain without incident. However, not all slopes harbor green light conditions, as an avalanche professional found on Heaven's Peak Thursday. While traveling in an area he had not visited this season, he wisely chose to dig a snowpit before committing to a large face. The snowpack structure looked terrible, and snowpack tests revealed poor stability. These red flags made for an easy decision of choosing a safe descent route different than that morning's objective. 

Avalanche activity has waned since our last snowfall nine days ago but has not entirely disappeared. Reports of fresh wind slab avalanches large enough to bury or injure a rider in central Glacier Park and the Flathead Range trickled in over the past couple of days. I enjoyed a day off in the Flathead Range yesterday, where I noted a recent wind slab and witnessed a dry loose avalanche from the north-facing steep rocky terrain. The dry loose trigger was either a falling ice chunk or wind deposited snow from gusty winds. Debris ran over 1000 feet and was large enough to knock someone off their feet. We were impressed with the duration of the slide, which seemed to go on for several minutes.

The return of fresh snow will be a welcome respite from the various crusts which cap the surface in many locations. However, new snow will come with an increasing avalanche danger due to the existing surface and near-surface conditions - faceted loose surface snow, surface hoar, crusts with weak snow underneath. Expect to dial back terrain choices, way back from what we have gotten used to over the past two weeks. In your travels this weekend, take a good look at the surface and near-surface conditions before they get covered with fresh snow. Then envision that surface covered with a 6-12 inch storm or wind slab. Prep yourself by giving a thought on how to navigate the terrain during a period of elevated danger.

 

 

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