Boletín de aludes

Snoqualmie Pass

Northwest Avalanche Center
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Peligro de aludes

Fri
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
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

Windy conditions will persist at Snoqualmie Pass on Thursday, maintaining our concern for avalanches in wind-drifted snow. Look for these unstable pockets to develop on convex slopes or near rocky outcrops. At lower elevations, a battle between weather factors could result in mixed precipitation types but likely not much avalanche hazard.

Problemas de aludes

  • Wind Slabs

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

    Strong easterly winds will continue throughout the day on Thursday, keeping Wind Slabs as the most likely avalanche problem you’ll encounter. Easterly wind events can often drift snow onto different aspects than you may be used to and usually result in more mid-slope cross-loading. Regardless of aspect, look for these slabs to develop on specific terrain features such as convex rollovers, the leeward side of ridgelines, or rocky areas such as the base of cliffs and confined gullies. If you can find a small test slope that has a smooth pillow-like pile of snow on it, use the opportunity to see how the snow reacts to your weight to help determine the slab’s reactivity. Actively blowing snow, textured surfaces, and fresh drifts can help you identify wind-loaded features you should avoid. 

    (1/4/2023)

    Wind gusts drifted snow into shallow slabs at the base of cliffs on 1/4 in the Alpental Valley.

    Photo: Joseph M Ewers

Avalanche Discussion

There should be somewhat complex weather factors competing for superiority up at the Pass on Thursday, leading to some uncertainty around how the day will play out. The main question revolves around a bump in temperatures in the late morning to early afternoon hours and if that will result in rain or freezing rain at lower elevations. 

In some respects, it doesn’t really matter, our BTL band is fairly beat-up and has already gone through a few Wet Loose cycles, most recently on New Year's Day. But there is still a chance you could encounter some Wet Loose activity if you find yourself in an area where it rains on dry snow. As you ascend toward the near treeline band, that’s the sweet spot where some dry snow may exist and rain may or may not reach. Of course, cool east winds are predicted to be ripping at pass level, so that could result in holding off the rain, producing freezing rain instead or even a few flurries and some wind-drifted snow. No matter how it shakes out, there isn’t likely to be very much in the way of new precipitation, so we’re expecting generally safe avalanche conditions to persist lower down.

On Wednesday, several skier groups along with Alpental Pro Patrol reported strong winds moving snow around at mid to upper elevations and shallow Wind Slabs starting to form. We anticipate similar conditions to develop on Thursday in many areas. In isolated locations, you could encounter shallow slabs overlaying weaker snow. Our best guess as to where they could exist is in the near treeline band on sheltered northerly slopes. If you find one of these pockets, slabs could break in some surprising ways by wrapping terrain features or breaking above you.

Despite the variety of outcomes with the weather, we suspect any avalanche to be confined to the newly drifted snow. On more southerly slopes, there could be a sun crust from New Year's Day that could act as a good sliding surface. While the depth of the Christmas Crust may vary depending on aspect, elevation, and exposure to wind, we do not have any concerns below this prominent snowpack marker at this time.

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