Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Sat
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Out of date — this forecast expired 4 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

On Friday, look for textured surfaces or actively blowing snow to help identify wind-affected areas to steer around. These avalanches may be easier to trigger near rocky terrain or on convex features. As you ascend in elevation, take extra care on northerly facing slopes where weak snow still exists deeper in the snowpack.

Avalanche problems

  • Wind Slabs

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

    On Friday, you could run into some wind-loaded terrain to avoid as you ascend in elevation. Look for textured snow surfaces or recently built cornices to help you identify aspects where these slabs could be lurking. If you notice smooth pillow-like piles of snow or feel that the snow is stiffer, you have likely found an area of concern. You’re more likely to trigger a slide on a convex rollover, unsupported slope, or near rocky terrain such as the base of cliffs or confined chutes and gullies. 

    If you are on a northerly aspect at mid to upper elevations, slabs could break in surprising ways on weak snow deeper in the snowpack. See the discussion below for more details.

    (3/17/2022)

    A soft slab that failed naturally during the recent storm. This is likely a Wind Slab and you can see the large and overhung cornices above the slope.

    Photo: Dallas Glass

Avalanche Discussion

On Thursday, NWAC forecasters headed to the North Slope of Chair Peak to take a look for the 3/8 facet layer we have been tracking. These facets were found in two different pits just above the Early March Crust almost 3 feet (90cm) below the surface (N 4800-5300) but appeared to be moist and sticky. Deep tap tests consistently failed on this layer, but a propagation saw test was less inspiring. Avalanche Professionals across the valley found this layer of concern closer to 2 feet (60cm) below the surface (NNE 4600) and reported medium sudden planner results during their tests. 

At this point, you need to realize that this snow structure is still out there and could cause surprising avalanches. Avalanches on persistent grains can span far distances, break above you, or trigger remotely. If you’re planning on traveling in northerly terrain (NE-N-NW), then you need to take a look for these facets and see how they are reacting. That said, I wouldn’t bet my life on a single hole in the ground, and the existence of prior tracks on a slope doesn’t mean that it’s safe. Consider traveling in these areas as if dangerous avalanche conditions existed until the snowpack has had more time to heal. This same layer has awoken in the West South and West North Zones, so you can take a look at those forecasts for more details.

Apart from the facets, the upper snowpack above the 3/12 interface is layered and aspect dependent. On slopes that see direct sunshine, a thick but breakable sun-crust formed on 3/16. These slopes also have lots of recent wet avalanche debris and could produce additional wet avalanches if Friday’s drizzle, sun breaks, or generally warm springtime temperatures are able to soften the surface. On the shadier side of the compass, cold dry snow still exists near the surface and snowpack tests highlighted a few mid-storm layers, most notably a layer of graupel 8-10” (20-25 cm) below the surface. A quick shot of precipitation on Thursday night could add another layer of concern to the upper snowpack, with snow running quickly on the sun crust or thickening slabs on shady slopes. At lower elevations, we’re probably looking at rain or heavy wet snow. Although it's not a ton of water, it could move slopes closer to their tipping point if they haven’t already reached it. Add this to the list of layers to take a look at before committing to terrain.

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