Boletín de aludes

West Slopes North

Northwest Avalanche Center
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Peligro de aludes

Thu
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 6 months ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

After a full day of quiet weather, avalanches will be more stubborn to trigger. Upper elevations hold enough snow to produce an isolated large natural avalanche on steep slopes once the sun breaks down thin surface crusts. Limit your exposure to large open slopes in the direct sunshine, and steer around pockets of wind-stiffened snow near ridgelines.

Problemas de aludes

  • Loose Wet

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

    Typically the first sunny day after a storm sheds much of the dry snow on cliffs and steep open slopes. Tuesday's shed activity might help you identify similar slopes that have yet to slide.

    Recent snow above the 2/7 crust remains susceptible to solar warming. Up to 16" of snow sits above this crust at elevations above 5000 ft. With light winds in the forecast, the sun's energy could moisten only a few inches or potentially more. Although we expect the former, in the latter case, entrainment could produce isolated large wet loose avalanches running on the crust. Track the snow surfaces as they are warming, note any signs of shedding starting to occur, and adjust your aspect to cooler shaded slopes before the transition ramps up. Natural wet loose avalanches gain momentum on large steep slopes, so keep your eyes out for the slopes above you.

    Example: A small natural wet loose on a SE aspect of Mt Herman.

    Photo: Jason Speer

  • Wind Slabs

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

    6-8" of new snow accumulated Monday through early Tuesday with enough wind to form reactive drifts. You might encounter more widespread wind-stiffened snow above a rime crust at upper elevations. At middle elevations pockets of wind-affected snow overly the 2/7 crust. You could get wind-stiffened snow to shear off one of these crusts on steep, unsupported slopes on Wednesday. Use the direction of fresh, sharp wind lips or cornices to areas of cohesive snow before you engage with them on a steep slope.

    Example: Extensive cracking on a wind lip feature suggests avalanches are possible on a steep slope nearby.

    Photo: Irene Henninger

Avalanche Discussion

A slightly cooler early weak snow storm brought 6-8" of snow to the Baker Backcountry. This lower density snow overlies a 1/2" rime crust at upper elevations with 8" of older denser snow above the 2/7 rain crust. Below 5000 ft, the recent 6-8" of storm snow sits directly on the 2/7 crust at lower elevations. While the bond between various snow layers and the underlying crusts are generally improving, crusts are likely to play a role in any more significant avalanche activity on Wednesday. An observer on the White Salmon found the 2/7 crust down 22" at 6400 ft. Carefully evaluate the bonds with these crusts before engaging with more committing terrain. 

Avalanche danger is currently limited to the snow above the 2/7 crust. If you encounter less than 4-6" of snow above that crust in your terrain, there is minimal avalanche concern in your local terrain.

You may continue to expect significant variation in snow totals throughout the zone.  The more significant slug of moisture on Saturday brought 2" of precipitation to Heather Meadows and Elbow Lake, while many other stations saw only half to a quarter of that. Farther east and colder sites, such as Park Creek Ridge (4610 feet), recorded less precipitation—around 0.75 inches—but more new snow than warmer sites farther west. Elevation also played a role. The Brown Top SNOTEL near the Canadian border (5840 feet) has a base depth well over 100 inches and picked up about five inches of new snow in the last storm, despite typically being drier. 

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