Boletín de aludes

Flathead Range & Glacier NP

Flathead Avalanche Center
Ver en el mapa

Peligro de aludes

Sat
Alta montaña
2 · Moderado
Límite del bosque
1 · Débil
Bajo el límite
1 · Débil
Open full map
Desactualizado: este boletín caducó 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Think twice before riding recently wind-loaded terrain at upper elevations. Old hard slabs and cornices may fail in unpredictable ways. If the sun thaws the surface on high slopes above the low cloud deck, use caution on very steep solar aspects with wet snow. Sheltered slopes above about 6000 feet have the softest snow and the safest riding.

Problemas de aludes

  • Wind Slabs

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

    Hard slabs of drifted snow formed below saddles and ridges and on cross-loaded features like gullies Tuesday and Wednesday. Cornices grew large and loom over the most loaded slopes. Wind slabs became stubborn Thursday, though in isolated areas they may still be sensitive to the sudden weight of a rider, snowmachine, or cornice fall. Hollow, hard slabs are prone to breaking unpredictably, making slope cuts a risky way to test the problem. Look for softer snow and better riding on upper elevation slopes sheltered from the wind.

    (1/13/2022)

    FAC staff found older hard wind slabs and cornices on leeward aspects. These formed during the recent warm wet storm and were stubborn to trigger Thursday.

    Photo: Clancy Nelson

  • Loose Wet

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

    Observers across the region reported wet snow avalanches small and large on Thursday. In some areas with the shallowest snow cover, the entire snowpack became saturated with meltwater. At mid-elevations, the top 8 inches or so became wet. Thankfully, weather stations are reporting a good hard freeze Friday morning. Low stratus clouds or fog will keep the sun from hitting lower elevation slopes though the day. There may be more sun and a band of warmer air above about 6000 feet. If surface crusts break down or the snow underneath is still saturated enough for you and your machine to sink into wet snow, then you’ve found an isolated area where loose wet sluffs are still a problem. Because these are a little more likely at higher elevations, watch your overhead hazard below very steep, rocky terrain.

    (1/13/2022)

    This natural wet loose slide occurred on a low elevation steep southerly slope. Intense solar input warmed the adjacent rocks, which helped initiate this slide.

    Photo: Rick Ziegler

Avalanche Discussion

Above freezing temperatures and rain initiated a loose wet avalanche cycle on Wednesday. Ample sunshine and a lack of overnight freeze made the problem worse by Thursday afternoon. Observers reported many wet snow avalanches initiating from low and middle elevations. Low clouds and fog moved in overnight and all our weather stations sank back below freezing between 3pm and 10pm.   A surprising amount of new snow coupled with moderate to strong winds created reactive slabs of new and drifted snow on Tuesday and Wednesday. Riders were able to trigger small to large avalanches and a few cornices failed Wednesday morning. We found old hard wind slabs and cornices stubborn to stomping on Thursday.   Wet snow re-freezing and recent strong, but diminished, winds have left hard surfaces in exposed areas at all elevations. The snow is softer in sheltered terrain above about 6100 feet - above Wednesday’s rain/snow line.   The upper snowpack is dense and settled. Layers of weaker, faceted snow lie in the middle of the snowpack and near the ground above a crust that was buried in early December. We have not seen enough warning signs in our region to list these layers and a persistent slab problem. Though our neighbors in Fernie, BC have seen very large and destructive avalanches fail on old facets and crusts over the past week. Those avalanches initiated on rocky, southerly slopes with shallower snow cover.

Regiones cubiertas