Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Expect shallow, reactive wind slabs in upper elevation and exposed terrain. Small loose wet avalanches are expected to run on steep slopes that face the sun with daytime warming. The chances for deep persistent slabs have decreased, but the consequences remain high if one does release.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    Observers found reactive wind slabs on Sunday, and strong winds continued to transport snow near ridgelines. These slabs could be just a little larger on Monday with another inch or two of snow, and more wind.   Steer around obvious wind features like freshly drifted snow and wind pillows. If you find that similar conditions extend further down in elevation,  seek out lower angle and wind-sheltered terrain. Shooting cracks or hollow-sounding snow are signs you could trigger an avalanche on similar slopes. A wind slab avalanche could be enough to trigger a much larger deep slab avalanche.

    Cornices are large and sagging in some areas, keep on the lookout for these and stay well away from them. If cornices fall, they could trigger very large deep persistent slab avalanches.

    Cracks in recently drifted snow are signs that an avalanche might occur if the slope is steep enough.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    With fresh snow over a slick crust, warming temperatures and stronger sun, wet loose avalanches are expected to run on Monday. Look for these to happen on steep slopes that face towards the sun as the daytime warms up. Moist, sticky snow and rollerballs are good indicators that these could happen spontaneously. Time your travels to avoid steep slopes after they've had more than a couple hours of sun to avoid getting avalanched by a wet loose slide. The slick crust under the new snow may make for slippery travel, anyhow.

    Example small loose wet avalanches.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3–4

    Deep persistent slab avalanches are unlikely, but not impossible. For this reason, maintain a conservative mindset as you travel in the backcountry. Know that these deep persistent slab avalanches could still happen, because the snowpack structure needed still exists. The last recorded one was on March 1, but potentially March 3, and enough evidence exists that we are not yet ready to remove this problem.  Avoid going into, or underneath open or sparsely treed terrain with large start zones above you. 

    This deep persistent weak layer of facets over a slick crust formed mid-January, and is now buried 6-10+ feet deep. We’ve seen avalanches failing on this layer for well over a month now. Slopes of greatest concern are east, south and west aspects above 5000ft. The most likely way that an avalanche will occur is if a cornice were to fall, or a group of people stood on a shallow spot on the slab. 

    (2/27/2021) A deep persistent slab avalanche ran naturally at around 10:30pm on February 26th in a path known as West Camp off Rock Mountain above Highway 2. It filled and expanded the runout zone and the airblast hit the highway. Southeast to Southwest aspects with the crown running from around 6,200ft to 5,400ft.

Avalanche Discussion

Observers reported shallow but reactive wind slabs on Arrowhead on Sunday. Winds were strong near ridgelines, and transported snow through the day. Cold temperatures and clouds generally inhibited much sun effect, but Monday should be a different story with stronger sun affecting the snow surfaces.

Last Monday, WSDOT avalanche teams triggered an 8ft deep D3 avalanche on the southeast face of Rock Mountain east of Stevens Pass (our last avalanche known to have failed on the persistent weak layer in this zone). In the Chiwaukum Mountains, a natural D3.5 avalanche in upper-elevation north-facing terrain is suspected to have run on Sunday. A massive avalanche (D4) ran naturally in the West Camp path on Rock Mountain a bit  over a week ago. Viewing the tree-laden debris gives you a taste of the destructive potential of that avalanche as you drive along Highway 2 east of Stevens Pass. The mountains still demand respect because of the potential for these very large avalanches.

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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