Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The Pass received a massive amount of snow this weekend that transformed the landscape and built the snowpack. While soft snow abounds, keep your eyes peeled for features where the wind may drift the snow into slightly thicker and firmer slabs. Blowing snow and sharp cornices can help highlight which areas you want to steer around.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2

    It’s been stormy at the Pass for several days, but the potential avalanches you want to look out for could be forming in front of your eyes. Moderate winds and continued snowfall could form soft new slabs that you can trigger in wind-prone areas. The change in the firmness of the snow surface could be subtle, so watch for other signs such as a textured snow surface, blowing snow, or sharp cornices to indicate which features could hold wind slabs. If you suspect a slope is wind-loaded, steer around and seek out less wind-affected areas. 

    Even though we think the greatest hazard will exist in the shallow surface slabs, several feet of snow accumulated in this zone over the past several days. Avalanches could break into recent storm interfaces or pockets of deeper winds slab. This is most likely if you travel on very rocky or unsupported slopes.

    (12/13/2021)

    Example: Wind textured snow surfaces like this are a great indication of potential wind slabs. 

    Photo: Robin Pendry

Avalanche Discussion

It may feel like it’s late, but winter finally arrived with a vengeance. Near constant snowfall since Wednesday 12/8 caused the snowpack to grow by 3 feet plus at most elevations. This dramatically changed the landscape. Several small human-triggered storm slabs occurred during the storm cycle as recently as 12/12. However, many travelers reported generally unconsolidated surface snow on Sunday and encountered small loose dry avalanches. 

Even though the snowpack may feel more winter-like, it’s still early season. The snowpack is relatively thin and highly variable. This makes assessing the snowpack very challenging and increases our uncertainty. Besides all the recent storm interfaces, there are 2 snowpack markers we’ve been watching. At the base of the snowpack, you’ll find the mid-November crust. This very strong block of ice and melt forms survived the Thanksgiving rain on some mid and upper elevation slopes. A much thinner and weaker crust (12/8) can be found in some locations about 4-6” above the late November block or above the ground. In nearby zones, small weak faceted snow was seen just above this layer. So far, no avalanches have been reported on this layer, but if you dig in the snow, see if your snowpack tests fail suddenly or slide easily around this layer. 

Open creeks continue to pose a challenge to travelers, particularly at lower elevations. Choose your routes and creek crossing carefully. 

Preliminary Report: On Saturday morning, December 11, a party of six backcountry tourers were traveling uphill in a closed section of the Crystal Mountain Ski Area known as Silver Basin. The party triggered a large avalanche on an NE to E facing slope at approximately 6600’. While all members of the party were initially caught, four were fully buried. A nearby party of two witnessed the event and immediately assisted in the rescue. Crystal Mountain Ski Patrol was also notified and responded to the scene. Unfortunately, one of the fully buried victims did not survive. NWAC and Crystal Mountain Ski Patrol will collaborate to conduct an investigation. Our deepest condolences to the family, friends, and community. 

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