Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 2 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

The mountains are in for a big change on Saturday. A nasty rain-on-snow event should create dangerous avalanche conditions and may release natural slides from steep rocky terrain. Dial it back and stay off steep open slopes until this event has time to play out.

Avalanche problems

  • Loose Wet

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

    Rain is a classic avalanche red flag indicating unstable snow. We think you’re most likely to see loose avalanches as the surface snow becomes wet and runs on an underlying crust. These will be a much different beast than the small wet slides we’ve experienced lately. These avalanches could be very wet and heavy. Some may even gouge, entrain deeper snow, and become large. While rollerballs and small natural slides will be great clues, don’t overlook the obvious… rain. You may trigger slides on steep open slopes, particularly at mid and upper elevations where substantially more snow exists. 

    Other flavors of wet avalanches (glide and wet slab) could occur. These would be most likely during and immediately following periods of heavy rain. Blobs of snow could shed from steep rocky faces. Keep an eye on what’s above you and limit any time you spend underneath complex and cliffy terrain.

    (3/25/2024)

    Example: These large natural wet loose slides originated in steep rocky terrain last season. You could see similar avalanches on Saturday.

    Photo: Dallas Glass

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    As temperatures cool in the afternoon, snow should return to the higher elevations at the Pass. The snow should generally bond well to the warm, wet surface. However, strong winds could form slabs along the lee sides of ridges and below cliffs. Given the stormy nature of the day, it will be very difficult to spot and assess potential wind slabs. You may feel them underneath you as firmer or deeper snow. Give any steep, potentially wind-loaded area a wide berth. Seek our more sheltered and lower angled terrain.

    (3/10/2024)

    Example: A shallow wind slab in the top of a chute/below a cliff from last season. 

Avalanche Discussion

At its basics, this forecast is simple. It’s going to rain… rain well above the tops of the peaks around the Pass. That should destroy any of those pesky surface hoar or near-surface facets that formed during this prolonged dry spell. The complex part comes from how the cold, generally dry, but strong snowpack will react to the rain. We don’t think this will be one of those events where things will come apart. Instead, the upper few inches of softer snow will likely get wet, but the remainder of the snowpack appears strong enough to handle the rain. 

An NWAC forecaster and an avalanche professional traveling in different areas of the Pass on Friday found similar conditions. They each reported about 4 inches (10cm) of snow over the 11/24 crust. Lower elevation snowpacks were very thin, but depth increased dramatically above 4000 ft. 

Early season conditions still exist. This rain event could only make them worse. Expect open creeks, bare ground, downed logs, and all other manner of travel hazards, particularly at lower elevations.

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