Avalanche forecast

Stevens Pass

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Wind slab avalanches may become more reactive during the course of the day. As the next storm approaches, east winds should ramp up through the pass and could form slabs in unusual places. Check the slopes for wind drifted snow, strong over weak layering, and be ready to stay off wind-loaded areas if you find signs of instability like shooting cracks.

Avalanche problems

  • Wind Slabs

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

    As the next storm approaches, easterly winds should begin moving snow at lower and mid-elevations through the pass. Areas that are exposed to the main east/west pass corridor tend to see the effects of this type of wind event. Currently, snow surfaces in these areas are low-density, and could get easily transported into unusual locations. Slabs will most likely be small, but could become larger in areas with heavier wind loading and at higher elevations. Recently buried surfaces are weak, so fresh slabs could become quite reactive.

    Look for signs of instability such as recent slab avalanches, and shooting cracks. Steer around areas with stiffer snow, drifted snow, and wind rippled snow. Use safe travel protocols and consider each slope separately. Very large avalanches have been occurring in the West North zone on a deeply buried layer of surface hoar. A very large avalanche was observed off Mt Mastiff from around the 26th in this zone. While triggering a slide on these deeper interfaces appears unlikely, caution is warranted in larger, alpine terrain of the region. At the very least, it's worth discussing these events with your partners before venturing into complex terrain.

     

    (12/31/2021) A ski triggered wind slab avalanche in the Baker backcountry. Similar activity could be expected from higher terrain at Stevens Pass on Saturday. Photo: Lee Lazarra 

Avalanche Discussion

Observers noted winds picking up from the SW at upper elevations on New Years Day, and a few small natural wind slabs occurred. These were mainly in alpine terrain and on NE-E aspects. Small loose dry avalanches were also reported from sheltered locations. Observers on a NE aspect at 6,500ft in Whitepine Drainage found a thicker wind slab underneath the newer snow. They performed a compression test and the slab popped off (sudden planar) on a small faceted layer (which may be the 12/29 interface). They also found weaker, faceted snow down about 2.5ft. 

The sun was out the past few days, so many steeper south facing slopes have a thin sun crust. The recent cold, clear weather has created a variety of weak surfaces on many aspects. We were able to identify small faceted grains at the old/new interface (12/29) on both shaded and sunny aspects on Lichtenberg on Friday. These didn't appear to be problematic because there was only fluff atop the layer and no slab, yet. Another layer that bears watching is the Solstice layer. This may present as a thin crust with small facets above and below at low/mid elevations, but on high shaded aspects it may be found as surface hoar. This layer is roughly 3ft down from the surface. A very wide, very large avalanche ran off the E Face of Mt Mastiff around the 26th, and may have been on this layer. Up in the West North zone, natural deep persistent slabs have occurred as recently as New Years Eve. These were on the Solstice layer, found as buried surface hoar. Avalanche danger is expected to increase substantially Sunday night into Monday, as slabs build up over weaker snow layers.

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