Boletín de aludes

Swan Range

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 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Breezy winds are drifting overnight and recent snow into thin slabs that may be reactive to the weight of a rider or their snowmachine. Slabs will be larger and more dangerous below ridgelines at the upper elevations. Look for blowing snow and surface clues to alert you to their presence. Slopes sheltered from the wind hold softer and safer snow.

Problemas de aludes

  • Wind Slabs

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

    Friday, observers noted blowing snow and thin wind slab development. With a few inches of snow overnight and increasing winds, we anticipate fresh slabs to be a bit thicker and more widely distributed than yesterday. As you gain elevation, look for blowing snow as an obvious clue that new slabs are forming. An etched or scalloped surface shows that winds have recently been at work. You may find slabs beneath ridgelines and in cross-loaded gullies. You'll know you have found a slab if the snow feels denser than what you had been riding. Cracks shooting away from you are a red flag directing you to seek out softer snow found in wind-sheltered terrain.

    (3/11/2022)

    A skier triggered this fresh deposit of wind-drifted snow on a northeast-facing, upper elevation slope in the Flathead Range during a period of active loading. HS-ASc-R1-D1-I. 

    Photo: Stefan Beattie

Avalanche Discussion

Temperatures warmed overnight and are the warmest in about a week. As high pressure builds today, expect relatively balmy temperatures by this afternoon. The workweek was characterized by cool weather, a period of easterly winds, and a quick pulse of dry, low-density snowfall. The "Colorado-like" temperatures kept the new snow loose and enjoyable. Without this shot of fresh snow, we would have been riding on a stout block of ice leftover from the warm, wet Atmospheric River. Check out this week's Conditions Blog for a great recap of conditions.

We only received three observations on Friday, but they all mentioned loose surface snow transported by southwesterly winds. Riders in the Middle Fork found thin slabs in gulleys and on rollovers. They deliberately triggered a relatively harmless 4-8 inch thick slab with a ski cut. Observers in the northern Whitefish Range noted soft surface snow, surprisingly good riding, and light blowing snow. I traveled to southern Glacier Park with Megan, the FAC March intern, and we observed light wind loading at all elevations with minimal wind slab development. With a bit of new snow overnight and increasing winds, we have raised the avalanche danger in the Flathead Range and Glacier National Park to MODERATE at upper elevations and expanded the distribution of the wind slab problem to include mid and upper elevation leeward slopes.

Recent sunny weather left a thin sun crust on steep slopes facing south and west. Today's increasing temperatures will warm the dry, loose surface snow on slopes that escaped the effects of this week's solar input. Expect small Wet Loose activity to develop on these slopes. Snow falling from branches or small rollerballs are clues that warming is occurring. As the bonds in the surface snow weaken, small wet loose slides may occur. Due to the limited amount of loose surface snow found at low and mid-elevations, these should remain small in size. 

The Friends of The Flathead Avalanche Center and FVCC are hosting the last Intro to Avalanches next weekend. And on March 22, join us online for a Community Chat where we review recent conditions and debrief a near miss. 

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