Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 3 years ago.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

Highlights

Monday might look like the calm before the storm but don’t write it off. You could trigger a shallow avalanche in the new surface snow that grows much larger as it moves downhill.

Avalanche problems

  • Storm Slabs

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

    A gradual warmup on Monday could create an upside-down snowpack. Even though the newly forming slab should be relatively shallow, it may fail easily on the colder weaker snow below. This could produce lots of cracking and small slab avalanches on convex rollovers. 

    However, in some spots, these shallow slabs could start to entrain the cold, dry snow underneath and grow much larger and deadly. This is most likely on very steep slopes, at higher elevations, and in rocky complex terrain. Small slopes and uptrack tests should provide excellent information about the new shallow surface slabs, but may not fully let you know if these slides will entrain additional snow. 

    Similarly, you might still encounter an older wind drifted pocket. These would be most likely in the tops of chutes, along the base of cliffs, or near exposed ridges.

    (1/6/2024)

    You could see smallow storm slabs on similar features Monday. Some might gather more snow and grow larger. 

    Photo: Rob Coppolillo

Avalanche Discussion

Light snowfall throughout the day will be accompanied by a slow rise in temperatures. Easterly flow should keep the Pass all snow, at least through sunset. However, once the sun goes down, things could get really spicy. A switch to westerly winds at Pass level will allow temperatures to climb right as precipitation starts to increase. This will probably result in a large natural avalanche cycle. This won’t be the night to camp out in the mountains. 

On Sunday, most backcountry users reported excellent travel and a generally stable snowpack. Even still, we received reports of a couple of small human-triggered slabs. Similarly, snowpack tests showed these layers weren’t fully healed as they continued to fail. Since January 4, the Pass has received about a foot of snow at lower elevations and 20in higher in the terrain. This brings the total to around 3ft since 12/30. That means there’s a lot of snow on some of these older weak layers. So far, we haven’t heard of any slides below the new snow. However, in other zones, deeper weak layers are suspected in a handful of natural and human-triggered avalanches. We’re not quite ready to put these weaklayers to bed. Avalanches on these layers could break widely, wrap terrain features, and grow very large. 

The new snow dramatically helped travel conditions at the Pass. Even still, open creeks, logs, bushes, and small trees make travel more difficult than normal at lower elevations.

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