Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Mon
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Continued windy weather will only make it easier to encounter and trigger avalanches near and above treeline Sunday. Blowing snow, textured surfaces, and sharp drifts can all help you anticipate wind-loaded terrain. Steer around steep slopes where you find pillow-like slabs of snow.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Backcountry travelers triggered small wind slabs in a few locations Saturday around the Pass. Continued moderate to strong winds and a few more inches of snow will only make this problem worse (larger and more widespread). 

    Fortunately, these slabs should be easy to spot and avoid. Use visual clues to figure out where the wind is building slightly deeper and firmer slabs on the lee sides of ridges, along the base of cliffs, and in the tops of chutes. If you suspect an area is wind-loaded, look for ways to simply go around the pillow-like pockets. 

    In bigger, more wind-exposed, terrain, some of these potential avalanches could grow quite large and deadly. Give them plenty of space so you don’t accidentally find yourself on the edge of one of these bigger slabs.

Avalanche Discussion

While Sunday isn’t really a “storm” day, windy weather and continued light snowfall should help slowly build the avalanche hazard. So, you could experience the most dangerous conditions in the afternoon. 

You’re likely to encounter two distinctly different snowpacks as you gain elevation. Below about 4800ft, heavier wetter snow exists. This could lead to piles of rollerballs and even a few small loose wet slides. While these generally don’t pose much risk to you as a traveler, don’t let them push you into a deep gully or open creek hole. 

Higher in the terrain, conditions are much colder and drier, and you’ll find a more winter-like layered snowpack. At the moment we’re keeping an eye on all the snow above the 2/13 crusts (down 12-18in). However, we think most avalanche activity will remain above the 2/17 interface (down 4-6in). On southerly aspects, this layer is marked by a thin breakable crust. 

On Saturday, several observations from around the zone indicated wind transported snow near and above treeline. This resulted in a few human-triggered avalanches on NW-E aspects above 5000ft. These slides often ran quickly and in some instances entrained significant amounts of snow. A few observers reported very small slabs failing on the 2/17 interface in non-wind affected terrain. These isolated pockets could correspond to the buried surface hoar observed by NWAC’s team near Stampede Pass on Friday. A present this layer is rather shallow and often lacks a slab, but could be worth watching as it gets buried deeper.

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