Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

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

If you're planning a romantic trip to the mountains on Friday, bring plenty of layers and watch out for wind-loaded slopes. Fierce easterly winds have drifted snow into unstable slabs while increasing the load over buried weak layers. Wind slabs may exist in unusual locations, so use visual clues to help identify slopes to avoid.

Avalanche problems

  • Wind Slabs

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

    Strong easterly winds should eventually give way to moderate westerlies by the end of the day on Friday. Slabs formed over this windy period might overlay soft snow from earlier this week, making them more reactive than you're used to. Or they could sit on a melt-freeze crust on sun-exposed slopes, giving them a good sliding surface. With easterly winds, slabs form on different aspects than usual and sometimes further down in the terrain as slopes get cross-loaded. Visual clues such as actively blowing snow, textured surfaces, and fresh cornices can help you identify wind-loaded aspects. Even if slabs exist in some unusual locations, the type of terrain where they form will remain essentially the same. Look for them on the leeward side of ridgelines, convex slopes, the base of rocks/cliffs, or the sides of gullies/chutes.  Zoning in on pillow-like drifts, areas that look "fat," or stiff, hollow-feeling snow can help you identify slopes to avoid. 

    (2/12/2025)

    Natural wind slab avalanches were observed on Wednesday in the Alpental Valley. These slabs formed and failed without additional snowfall, only wind.

    Photo: Jonathon Spitzer

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    2

    As we add load to the snowpack through snow showers and wind events, the slab over our persistent weak layers should thicken. The question is how much load until these layers wake up and produce avalanches. Our hunch is we'll need a little more than what you'll find on Friday, but don't take that to the bank. Your best game plan is still avoidance of large open slopes, especially if they're wind-loaded.  Discuss the consequences of a slide with your loved ones if you are considering non-wind-loaded steeps on the shaded half of the compass. Your default should be to choose simpler, smaller, and lower-angle terrain. 

    (2/2/2025)

    This avalanche released after a audible whumpf. The slide failed on facets over a crust and released the entire width of the feature. NE, 3700ft

    Photo: Summit at Snoqualmie Professional Patrol

Avalanche Discussion

Thursday was another windy day. The anemometer at the top of Alpental hit 60 mph while the one at the top of Summit West reached the 40s. Shooting cracks, natural and human-triggered wind slab avalanches, and rapid loading were reported by avalanche professionals and the Summit at Snoqualmie Pro Patrol. Similar conditions were found on Wednesday afternoon as easterly winds ramped up and started moving around the low-density snow from our last storm.

As we look ahead to Valentine's Day, the easterlies should begin to calm down, but the wind slabs formed during this event will still be fresh for human triggers. A switch to westerly winds will be accompanied by a slow warm-up and possibly a second batch of wind slabs on Friday afternoon.

Wind-loaded slopes will be the more in-your-face problem, but our persistent weak layers are still down there. They're a few feet below the surface and have been dormant for the better half of a week now. That doesn't mean this problem is over with. As we incrementally load these layers through snow showers and wind over the weekend, keep an eye on how this problem changes. We may be bumping the likelihood to possible. Obviously, if you experience whumpfing collapses or see widely breaking avalanches, dial your terrain selection way back, and please let us know about it.

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