Boletín de aludes

Stevens Pass

Northwest Avalanche Center
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Peligro de aludes

Sat
Alta montaña
3 · Notable
Límite del bosque
3 · Notable
Bajo el límite
3 · Notable
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Desactualizado: este boletín caducó last year. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Expect dangerous conditions from Thursday night through Friday night, as snowfall will intensify along with gusty southwesterly winds. The most dangerous avalanches will be at middle and upper-elevations where the wind forms deep slabs of snow. Stick to lower-angle, wind-sheltered terrain and consider avoiding slopes over 35 degrees. 

Problemas de aludes

  • Storm Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1.5–2.5

    With close to 1 foot of heavy snow expected by the end of Friday, you will be able to trigger avalanches on a variety of slopes. Any avalanche in the new snow could be dangerous, but they will be eaisiest to trigger and could be big enough to bury you on leeward slopes at middle and upper elevations. Avoid wind-loaded sides of ridges and steep slopes where you see blowing snow and wind-stiffened surfaces.

    Use small test slopes to see how the snow reacts before committing to bigger terrain. If you see recent avalanches, cracks shooting from your equipment, or snow that slides easily, stick to well-supported terrain and slopes under 35 degrees.

    Below 4,000ft, you may find moist snow and a chance for wet avalanches. At upper elevations, there's a chance that you could trigger a large avalanche, over 3 feet deep, especially in steep, cliffy terrain. See a recent example of a deep triggered avalanche in Mill Creek.

Avalanche Discussion

There have been numerous triggered small avalanches in the past week, mostly on leeward, wind-loaded slopes. Again on the 20th, Stevens Pass Patrol triggered small wind slab avalanches during control work. Recent wind slabs have formed from west or southwesterly winds. An observer in the backcountry reported triggering similar avalanches on a cross-loaded west aspect in Mill Creek at 5,000ft. Another observer was able to trigger a small storm slab avalanche on an unsupported feature in wind-sheltered terrain.

We're experiencing a multi-day period of incremental storms, accompanied by periods of strong winds. In the Stevens Pass area, you can find 2.5-3 feet of settled storm snow that has accumulated since March 9th. This week, NWAC forecasters and other observers have reported reactive wind slabs failing on mid-storm interfaces. Dry and wet loose avalanches have been common on shady and sunny slopes, respectively. In all, over 20 avalanches have been reported in this and surrounding zones, including at least four avalanche involvements.

The snowpack underwent a major transition since the atmospheric river (AR) storm of February 21-25th. This AR crust is now buried over 4ft deep above 5000ft. You'll find a number of crust and old snow layers resting above this crust. On most slopes, the recent snow since the 9th is sitting on a crust from warm temperatures and sun. On high elevation, northerly aspects, there's a chance that you could find weak snow (buried surface hoar or possibly facets) at the March 9th interface, 2.5-3 feet below the surface. On the 10th, observers in the Foss River drainage reported triggering isolated avalanches, which are suspiciously indicative of this weak layer.

If you make it into the backcountry, please share with us what you find by submitting an observation HERE or on the Avy app. 

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