Boletín de aludes

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Northwest Avalanche Center
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Peligro de aludes

Fri
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
2 · Moderado
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Following a significant winter storm, use visual clues to identify where fresh wind slabs may have formed near and below ridgelines.  On sheltered and very steep slopes,  use care above terrain traps where a fast-running loose dry avalanche could catch you off guard.  With a healthy snowpack at lower elevations and in the foothills, you'll need to turn on your avalanche brain for any open steep slope with enough snow to slide. 

Problemas de aludes

  • Wind Slabs

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

    Moderate winds recorded at the Washington Pass during the Tue/Wed storm will have easily transported fresh low density snow onto lee slopes.  On Wednesday night, a period of easterly winds may be significant enough to cross-load some aspects or form thin wind slabs on unusual aspects. Following a significant winter storm with few direct observations, the bottom line is that you'll need to identify recent wind loading patterns when pushing into higher elevation and wind-affected terrain. 

    Wind slab avalanches triggered in the new snow may be large enough to cause injury or worse.  Use caution when approaching the leeward sides of ridges where you encounter stiffer slabs, see freshly built overhanging cornices or observe pillows of wind-drifted snow.  If you see signs of recent slab avalanches, see shooting cracks in the new snow, it's time to shift to lower angle slopes. 

    (11/27/2022)

    Cracking of wind-stiffened slabs near Stevens Pass Mountain Resort.

    Photo: Joe Dellaporta

  • Loose Dry

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

    There's a lot of fresh, soft snow out there to enjoy.  Before engaging with very steep wind-sheltered terrain, take stock of your surroundings.  Loose avalanches may be big enough to knock you off of your feet. These avalanches could push you into a dangerous area if you're not paying attention.  Even though the snowpack is building quickly, you could be injured by hitting shallowly buried logs or other obstacles. 

     

    (2/27/2022) A natural loose dry avalanche, size D1.5 that occured on February 27th, 2022. 6,500ft WSW, Cutthrout creek. Photo: Josh Hirshberg

Avalanche Discussion

Across the zone, about an inch of water was recorded from West to East Tuesday through Wednesday afternoon, looking at the Washington Pass, Mazama and Salmon Meadows weather stations.  This likely translated into 12-16" of new snow with a growing snowpack at all elevations.  There was a slight warming trend towards the end of the storm Wednesday morning.  A few additional inches of snow are forecast Wednesday night through Thursday morning along with shifting winds. 

Prior to this storm, on Monday and Tuesday, observers near Cutthroat peak reported snow depths of 3-5 feet following about a foot of snow that fell last weekend. They noted only minimal wind-affected snow at upper elevations.  They found some small faceted layers near the ground and between late November crusts, but no results in snowpack tests or signs of recent avalanches.  We have limited observations on the extent and distribution of weak, faceted snow from mid-November. An observer noted being able to easily push a pole through the snowpack to the ground in the Hairpin Valley on the 22nd, indicating a weak snowpack. On the 25th, observers found light rain up to about 7,600ft at Blue Lake Col. 

It's still early season, and the snowpack is building. Hazards exist such as shallowly buried trees, rocks, and open creeks. Let us know what you see by submitting an observation.

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