Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Out of date — this forecast expired 6 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

As the skies begin to clear, keep your attention on the recent snow. You can still trigger avalanches in areas where the wind formed unstable slabs, particularly at upper elevations. Steer around slopes with smooth pillow-like deposits and below fresh cornices.

Avalanche problems

  • Wind Slabs

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

    Monday’s stormy and extremely windy weather formed your primary avalanche concern for Tuesday by drifting snow into thicker and easier to trigger deposits. When the winds blow as hard as we saw on Monday, you can experience erratic loading patterns with wind slabs formed well below ridgeline, along the sides of mid-slope gullies, and on exposed slopes at lower elevations. Watch for textured snow surfaces, fresh cornices, and drifts behind objects that indicate wind loading on nearby slopes. When you suspect wind transported snow, avoid areas greater than 35 degrees. Expect evidence of wind loading to increase as you ascend out of the trees and into higher terrain.

    (11/28/2020) Example from White Pass: Textured surfaces like this indicate wind loading on nearby slopes.

Avalanche Discussion

Four to eight inches of recent snow accumulated above a new interface (11/30). In some locations, this may be a firm crust causing the snow to bond poorly. In areas further east, or in shaded sheltered spots, this could be buried surface hoar. Either of these interfaces may allow you to trigger avalanches more easily. Take time to gather observations at this layer prior to stepping out into large or consequential terrain.

Transition is the word of the day for Tuesday. The weather and snowpack will transition from cold and stormy to sunny and warm. Often times this presents a tricky problem for the forecast. If you find yourself peeling off coats due to the sunshine, chances are the snowpack is feeling the warmth too. You could see a few rollerballs and loose wet avalanches particularly at lower elevations and west of the Pass proper. These are most likely to occur in areas of soft unconsolidated snow. 

You will find a large disparity amongst the height of snow by elevation at Snoqualmie Pass. At pass level and in areas further east, at thin (24-36”/60-90cm) early season snowpack exist full of obstacles to ruin your season. Above 4000’ the snowpack becomes much deeper (60-75”/ 150-185cm) and coverage more complete.

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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