Boletín de aludes

Snoqualmie 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 5 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Yet another night of above-freezing temperatures and a potentially shallow freeze will continue to push the wet snowpack towards the breaking point and increase the potential for large springtime avalanches. Pay attention to the terrain above you. Choose your routes and travel times to avoid going underneath large rocky slopes especially during the heat of the day.

Problemas de aludes

  • Loose Wet

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

    Conditions will change rapidly on Friday as warm temperatures and sunshine cause the upper snowpack to become wet and unstable. This will happen in the morning on easterly slopes before quickly spreading to other aspects. After nearly three days of hot weather, the snow seems primed and ready for large wet avalanches. These may not be the normal loose wet slides you generally experience. You could see large natural loose wet avalanches that entrain significant amounts of snow or gouge into older layers. You’ll need to be mindful of the terrain above your head. Limit the amount of time you spend under steep and rocky slopes especially when they receive direct sunshine and during the warmest parts of the day. 

    While our primary loose wet concern stems from natural avalanches, you may also trigger these slides on any steep slope with wet snow. Once the thin overnight crust breaks down, you find wet punchy snow, or you see new rollerballs, seek out lower angled or more frozen terrain. Even small wet avalanches can easily carry you over a cliff or into a gully.

    (4/11/2021) Example: Be mindful of the terrain above your head. On Friday, steep rocky slopes like these may produce large loose avalanches.

  • Glide Cracks

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

    Crevasse-like glide cracks abound this season in the Snoqualmie backcountry. Now, five days into a stretch of hot and dry weather water may again reach the ground and cause these slopes to release. On Wednesday, a natural glide avalanche occurred near Stevens Pass and we’re worried about similar events in this zone. You may see snow shed from rocky faces or glide slabs releasing on steep smooth slopes. Either way, this challenging avalanche problem is best handled with avoidance. Don’t linger underneath cliffy terrain or areas where you see glide cracks on a slope. These avalanches can fail without warning at any time of the day or night.

    (4/15/2021) Glide cracks and a glide avalanche on the NW side of Granite Mt. NW, 4700'

Avalanche Discussion

The snowpack continues to struggle against the longest and warmest stretch of springtime weather of the season. This big change for the mountains may push the snowpack past its breakpoint on Friday. This will be the third night of above-freezing temperatures. Highs could reach well into the 60s. As we pass these critical thresholds, our concern for a more widespread spring cycle grows. So far, avalanche activity has remained rather small or, in a few isolated events, cornices triggered larger loose wet slides. 

On Friday, you could see any number of large wet avalanches: loose wet, wet slab, glide, and cornice. While the danger rating and the avalanche problems may seem rather commonplace, the current conditions are not. Give the snowpack time and space to adapt to this period of warm weather. 

If you choose to travel in the mountains: 

  • Travel early and plan to be back before the sun and warm weather develop substantial wet and unstable snow. 
  • Pay attention to the slopes above you and limit your exposure to large overhead hazards. These slopes may warm faster than where you travel. 
  • Anticipate how the snow will change in terrain you need to cross to return safely to the trailhead. Slopes you cross in the morning may react very differently later in the day. 

Daily avalanche forecasts will end on Sunday, April 18th.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home

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