Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Ongoing warm temperatures and strong sun will maintain a threat of wet avalanches on slopes steeper than 35 degrees. Time your travel to be off of and out from under sun-exposed slopes before the snow becomes wet and weak. Steer around wind features and drifts at upper elevations where you still may be able to trigger a large wind slab avalanche.

Avalanche problems

  • Loose Wet

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

    Wet avalanches will first be active on the east aspects and later on the west aspects. As you move through the mountains, take note of how much the surface snow has frozen or melted.  You may find dramatically different conditions at different aspects or elevations and as the day progresses. Plan ahead and be ready to move to slopes that are shaded or under 35 degrees. Move off of steep slopes before the snow is unsupportive and weak enough to entrain an avalanche. Tuesday will be the third day in a slow and ongoing wet loose avalanche cycle. There's still enough dry snow available to produce avalanches especially at mid to upper elevations and on northeast and northwest aspects. 

    (4/11/2021) Natural wet avalanches ran in very steep, east-facing terrain. Stevens Pass zone

  • Wind Slabs

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

    There's still a chance that you may be able to trigger wind slab avalanches on leeward sides of ridges where slopes are steeper than 35 degrees. Avoid thickly loaded leeward slopes and steer around unsupported and wind-sculpted features. Other indicators of wind slab conditions are textured surfaces and firmer or supportive dry snow. Wind slabs formed through the 10th with strong west through north winds. Expect an increase in east winds on Tuesday and a possibility for wind transported snow to form fresh slabs. 

    (4/10/2021) A small wind slab avalanche triggered on an inconsequential test slope. This was on a leeward, 40 degree slope at ridgetop. Lanham creek, E, 5,450ft.

Avalanche Discussion

On Sunday and Monday, observers reported numerous wet loose avalanches with a few that were big enough to bury or kill a person. Glide cracks have again begun to open in steep rocky terrain. Cornices loom over some ridgelines and may fall during the warm days this week. Use extra caution to avoid being on or under features with glide cracks and cornices. On Saturday, I traveled in the Lanham Creek drainage and was able to easily trigger wind slab avalanches on small test slopes on the leeward sides of a ridge at 5,500ft. I also investigated northerly aspects, which held a mostly dry, winter-like snowpack. 

At Snoqualmie Pass, a skier was injured on April 10th after getting caught in a wind slab avalanche that ran on a layer of weak snow. While the same weak layer hasn't been observed in this zone, it's worth keeping an eye out for it. If you travel to upper elevations, look for hard-over-soft layering 1-2 feet below the snow surface on cold, shaded slopes. 

A storm on April 9-10th delivered 20-40cm of very cold snow with strong northwest winds. The last two days brought mixed sun and clouds and slowly warming temperatures. An earlier storm on the 7-8th brought 20-60cm of snow. This was also followed by a brief warm-up and wet avalanche cycle last week. Both storms brought the most snowfall to the mountains near and west of the pass. Many northerly slopes hold a mostly dry snowpack with a handful of crusts in the top 5 feet. The upper snowpack on east through south through west aspects consists of melt forms in various states of being melted or frozen. The mid-January layer is about 6-8 feet below the surface and has yet to see melt-water on most slopes. This layer could potentially produce avalanches with future warming events.

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