Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

This has been quite the storm for Snoqualmie Pass. While it may be tempting to think the snowpack is becoming safer, more snow and moderate winds will keep conditions dangerous. Give the snowpack time to adjust to the new load by steering around steep open slopes greater than  35 degrees.

Avalanche problems

  • Storm Slabs

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

    Several days of snowfall, fluctuating temperatures, and windy conditions created several potential weak layers within the upper snowpack. On Sunday observations poured in from all over the zone of numerous natural and human triggered avalanches. Most of these failed on steep convex rollovers even well below treeline. With more snow expected Monday night and Tuesday, this avalanche problem isn’t going anywhere. At this point, the storm snow is so deep you may need more than a small slope or uptrack test to give you information. You’ll likely want to dig with your hand or shovel to look at all the snow above the prominent 4/8 crust. If you find firm over soft (strong over weak) or see layers fail easily, then you’ve located the storm slab issue. Give the snowpack time to heal by steering around steep open slopes, especially near convex rollovers. 

    You could find that avalanches trigger more easily and are larger in areas where the wind drifted the snow deeper. Since the wind blew from nearly every direction during this storm, you could encounter wind-loaded slopes on all aspects. Unless you’re standing on an icy wind stripped spot, anticipate the possibility that you could trigger a slab avalanche

    (4/10/2022) Widespread D1 storm slabs on convex features failed naturally during a period of high precipitation rates on the morning of 4/10. Photo: Andy Harrington

Avalanche Discussion

These recent storms have been very good to Snoqualmie Pass. As of Monday afternoon, 2 ft of snow has accumulated at road level, with more than 3 ft at upper elevations. There’s quite a bit of uncertainty with how much more snow the Pass could receive Monday night into Tuesday morning. One thing’s for sure, with cold temperatures, even modest water totals could turn into several inches of light fluffy snow. These storms accumulated atop 4/8 crust. This snowpack marker is easy to find on all aspects and elevations. You can use it to focus your observations on the upper snowpack. It will also help you locate deeper, more wind-loaded areas, and shallower wind stripped spots. We don’t expect any avalanches to fail in older snow below the 4/8 crust at this time. 

The other big question mark for Tuesday is the sky. This time of year, it doesn’t take much sunshine to send the new snow falling down. Right now, we expect skies will stay mostly cloudy and temperatures should remain cold. However, if you start to see the sun for significant amounts of time, then you should expect natural loose avalanches. Look for snow shedding from trees, rollerballs, and small teardrop-shaped avalanches to clue you into this potential change in the danger. Long periods of sunshine could result in many natural loose avalanches, especially on more southerly slopes. If you think these conditions are developing, get away from this type of terrain.

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