Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 5 years ago.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

Highlights

You’ll need to balance changing weather on Tuesday and how it might affect the snow. Choose terrain where you can easily identify avalanche paths and avoid steep slopes to manage these potentially dangerous and dynamic conditions.

Avalanche problems

  • Loose Wet

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

    In locations where the sun comes out on Tuesday, expect the recent soft snow to become wet, unstable, and slide downhill. Watch for new rollerballs, snow shedding from trees, and wet sticky surfaces as a precursor to avalanche activity. When you see these clues, seek out more shaded and colder terrain. The recent dry snow sits atop a firm crust on southerly aspects. This may allow natural loose slides to grow large and run fast. You could even see a loose avalanche act as a trigger for lingering slabs. Pay attention to slopes above you and limit the time you spend in complex terrain during periods of strong sunshine.

    (2/28/2021) Example: New rollerballs and small loose wet avalanches showing the snow surface becoming wet and unstable.

  • Storm Slabs

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

    Natural and triggered storm slabs occurred on Monday. The most recent storm formed an upside-down surface with a heavier slab above weaker snow.  Give the snowpack time to gain strength. You are most likely to trigger lingering slabs on convex rollovers, in rocky terrain, and near wind-loaded areas. Use small slopes, hand pits, and uptrack tests to identify and track the changes in the storm snow. As the sun comes out you could see different conditions throughout the day.

    (3/21/2021) Uptrack tests like this can be performed by any mode of travel. They can highlight weaknesses within the new storm snow as you travel.

Avalanche Discussion

Snoqualmie received an additional foot of heavy snow at mid-elevations Sunday night and Monday. This brings the storm totals since 3/18 to 24+”. A weak graupel layer found this weekend was buried by the recent storm and could continue to produce avalanches. This snow sits on a crust (3/18) on all aspects. On southerly-facing slopes, a very thick and strong crust exists. In shadier terrain and at upper elevations, the crust may be very thin and weak. 

At Pass level, fluctuating temperatures and several rounds of rain limited snow accumulations. Expect variable travel conditions at these lower elevations. As you ascend, storm totals increase dramatically above 4000’. 

Over the recent stormy period, cornices grew large and thin. In some locations, natural cornices failure occurred. As the sun comes out and temperatures warm, expect more of these overhanging waves to start falling down. Keep an eye out for these beasts looming above your head. Choose routes that limit the amount of time you need to spend below this mountain hazard. 

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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