Bollettino valanghe

Snoqualmie Pass

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

Don’t ignore the large number of avalanches that just occurred throughout the zone and the changes the snowpack has been through. Any triggered avalanche on Saturday may grow large enough to be deadly. Avoid unsupported slopes, terrain features greater than 35 degrees, and areas where the wind has drifted the snow into deeper piles.

Problemi valanghivi

  • Wind Slabs

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

    We have just wrapped up a wet and windy storm cycle in which natural and human triggered avalanches were seen in abundance. If you find yourself in an area on Saturday where the snow has not been dampened by rain or sun, such as upper elevations, cold and dry snow may still remain. It's in these areas where you need to be aware of piles of wind-deposited snow where you could trigger an avalanche more easily. Winds often deposit snow on the sides of gullies, the base of cliffs, and on leeward slopes, including convex rollovers. Textured snow surfaces and freshly built cornices can help you determine which way the wind was blowing and where to identify these features to steer around. 

    We have received a lot of recent snow and there are still potential weak layers in the upper snowpack that you need to be leery of. After receiving so much snow, triggering even a small avalanche could potentially create larger and more destructive avalanches by activating deeper layers or through entrainment. Take the time to dig down and look at the snow for potential weaknesses before committing to terrain, even in areas where you do not see any signs of wind-effect. If you find that the snow is failing easily in your test pits, there is heavy snow over weak snow, or you notice red-flag signs of instability such as shooting cracks and whumpfing collapses as you travel, avoid similar slopes over 35 degrees.

    (1/8/2021) This crown was spotted on Friday and submitted via a public observation. The crown is at the base of some cliffs where avalanches often trigger more easily. This is a terrain feature where the wind commonly drifts the snow into deeper piles. [N aspect, 5000']

Avalanche Discussion

It has been a few days since our last big loading event at Snoqualmie Pass and we continue to hear reports of avalanches within the zone. So we are not out of the woods, yet. Conditions are still primed for human triggered avalanches and the possibility remains that some of these avalanches could grow very large and destructive (D3). These very large slides could be categorized as low likelihood, high consequence. But now that you know the danger, it’s up to you to make good decisions not only for your own group, but those traveling around and below you. There remains a lot of uncertainty around this snowpack and what it could take to trigger some of these deeper layers. When you’re digging on Saturday, take a look for the 1/1 crust approximately 60-100cm down from the surface and really study the snow above it. We believe that any slides on Saturday should occur above the 1/1. But if that doesn’t satisfy your curiosity, you can dig a little deeper to the prominent 12/21 crust to get the full picture of what we have received for snow in the last ~10 days.

Some areas of the zone have received more rain or sun during the past week, dampening the snowpack, and creating some variability within the zone. This process will continue on Saturday where areas of the zone just to the East or West of the pass proper may receive more sunshine. In areas where slopes are receiving direct sunshine for prolonged periods, you could see Wet Loose avalanche activity. If you see rollerballs or notice snow shedding from trees and rocks, head for shadier slopes and be aware of the terrain above you. 

You need to continue to watch out for non-avalanche hazards such as creeks running high and large amounts of snow and branches falling from trees. The deep snow alone creates a hazard due to tree wells and deep snow immersion. Find out more information about deep snow safety HERE.

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.

Regioni coperte