Bollettino valanghe

East Slopes Central

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Sunday will be the mildest day of the weekend. The avalanche danger is generally Low, but large wet avalanches may become possible in isolated, very steep terrain with daytime warming.  Move away from large, complex slopes if you find unsupportable wet snow. 

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–1.5

    Avalanches may become possible on very steep slopes with daytime warming. Look for punchy, wet snow if surface crusts break by the afternoon. Once you begin sinking into wet snow deeper than your ankle, it's time to move off from steep slopes. If you find a thick crust topping snow surfaces, then avalanches are unlikely.

    On steep low elevation slopes, wet loose avalanches have been running on the ground. These are scary because they've been taking the entire seasons worth of snowpack with it. Stay out from under large steep slopes if there is no surface crust. Don't linger or stop in runout zones and creek beds where avalanches could drain into.  

    (1/14/2022)

    Wet avalanches have been taking all of the snow out, running on the ground. This one occurred on a low elevation slope in Tumwater Canyon around 1/12.

    Photo: Matt Primomo

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1.5–2.5

    With the warmest day of the weekend on tap for Sunday and multiple nights of above freezing temperatures, the potential for deeper wet slab avalanches may continue. Water pooling on crusts, weak layers, or the ground could initiate very large avalanches with a large trigger in the right area. Wet, deep and punchy snow can signal danger for this type of avalanche.

    With plenty of uncertainty surrounding this problem and the destructive nature of these avalanches, don't linger underneath large, complex terrain if you find a wet and unsupportable snowpack. This problem may linger until we get a solid freeze, or free water and warmer temperatures have a chance to transform the weaker snow grains into sintered, bonded grains. 

    (1/6/2022)

    A snow profile at 3000' at Snoqualmie Pass. Note the pooling water well below the surface. This could result in wet slab avalanches. 

    Photo: Alyssa Young

Avalanche Discussion

Snow surfaces have been freezing at night, and melting during the daytime (in the sun). Observers have reported variable conditions depending on aspect and time of day including sun softened snow surfaces, breakable crust, and supportable crust. We haven't had reports of any natural avalanches since Thursday, so we are trending towards lower danger. There is uncertainty for the potential to trigger large wet loose and wet slab avalanches with sun and very warm temperatures forecast for Sunday, hence Moderate danger. On Wednesday and Thursday, observers noted large avalanches off Wedge Mountain, Icicle Ridge, and Tumwater Canyons.

Before and during the last storm, large and very large avalanches ran naturally and were triggered by explosives on various deeply buried weak layers. The recent layers consisted of large stellars, facets, and surface hoar from 1/2 and 12/29. A decomposing crust from the Solstice was the bed surface for some slides at Mission Ridge. An even deeper crust from Early December showed propagation potential on high elevation, shaded slopes in the Icicle drainage. These layers are likely buried 3 to 8ft deep, though are becoming unlikely to produce avalanches at this point. 

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