Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

The wet and wild weather should continue Saturday maintaining dangerous avalanche conditions. Above the rain-snow line steer around open slopes greater than 35 degrees where you could trigger a slab avalanche in the new snow. At lower elevations, watch for new rollerballs or piles of debris that indicate wet and unstable conditions.  

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    You could find an additional foot or more of snow at mid and upper elevations by the end of Saturday at the Pass. Forecasted changes in temperature, precipitation rate, and wind speed should create weaklayers within the new snow that you can trigger. Avoid traveling on open slopes greater than 35 degrees particularly during periods of heavy snowfall. You can use hand-pits and hand-shears to highlight these potential weak layers in the new snow. Small slope tests and up-track tests can help you see how they respond to your weight. In wind loaded terrain, expect avalanches to be deeper and trickier to manage.

    (12/31/2020) Example of a small slope test resulting in shooting cracks.

  • Loose Wet

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

    Rain should continue to inundate the lower elevations of the zone. Several natural loose wet avalanches were reported on Friday. While we anticipate most of the natural loose avalanche activity occurred during the initial rain event, wet snow hazards remain. If you see new rollerballs or tear-drop shaped avalanches steer around similar slopes. Loose wet avalanches can appear slow and easy to manage, however, with all the wet snow, these avalanches could grow larger and carry you into terrain traps. 

    Along with loose avalanches, we’re becoming increasingly worried about the chance for natural glide avalanches to occur. These avalanches are tricky to predict, but all the recent rain has our attention. Don’t linger in large avalanche paths and give slopes with crevasse-like glide cracks a wide berth.

    (1/1/2021) Example: New rollerballs on the Valley Rd near Paradise, Mt Rainier National Park. Clues like this indicate the surface snow is becoming wet and unstable.

Avalanche Discussion

Snoqualmie Pass has seen near non-stop precipitation now for 4 days resulting in numerous natural and triggered avalanches. Snow continues to pile up at mid and upper elevations. As the storm totals grow, so does our uncertainty. It becomes harder to predict which layers could fail in an avalanche. At this point, any avalanche could entrain significant storm snow and grow larger. Use extra caution if you travel near larger avalanche terrain or venture into the upper elevations. 

A freezing rain event on Friday was reported in the Alpental Valley. This could create a slick bed surface for avalanches when snow accumulates above. If you see an icy layer in the upper snowpack, anticipate that avalanche could trigger more easily. 

At lower elevations expect difficult travel conditions with wet, heavy, punchy snow and open swollen creeks. 

I’d like to thank all of you for submitting your observation in 2020! As of today, we have had 92 observations from the Snoqualmie zone on our public site. Your observations help us create the best possible forecast. Keep it up in 2021!. 

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