Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Wed
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Snoqualmie Pass is primed for wet avalanche activity as the sun warms the snow on Tuesday. They’ll be more likely on sun-exposed slopes holding dry snow. If you notice rollerballs or fan-shaped debris piles, make your way toward shaded aspects.

Avalanche problems

  • Loose Wet

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

    If the sun destabilizes a dry snow surface, anticipate wet avalanche activity to follow. These slides often start at a point and fan out as they move downhill. They could entrain all of the snow above the Early February Crust and potentially grow large or trigger slabs as they descend. Rollerballs/pinwheels and snow shedding from rocks/trees are precursors to wet loose avalanches. If the snow surface is wet and sticky and you notice these signs or see fan-shaped avalanche debris, head for shaded slopes. The target zone for the highest hazard will be sun-exposed slopes with dry surface snow.

    (2/12/2024)

    Widespread rollerballing was observed in the Alpental Valley as the snow surface softened.

    Photo: Trevor Kostanich

  • Storm Slabs

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

    On the shaded side of the dial, you might encounter a lingering slab in Monday’s storm snow. Use quick hand pits and small test slopes to get an indication of how the snow over the Early February Crust is bonded and reacting to your weight. Heavy snow over weak snow or clean and easy failures in your tests indicate that you should avoid convex, unsupported, or wind-loaded features over 35 degrees. 

    (1/11/2024)

    Example: The small test slope in this photo produced a mini avalanche, indicating unstable snow. 

    Photo: Andy Harrington

Avalanche Discussion

On Monday, the Pass picked up close to 9 inches of snow at upper elevations while roughly 2 inches fell at lower elevations. There was a warming trend throughout the day, and WSDOT’s weather station reached the 40s. Avalanche professionals in the Alpental Valley reported that this warmup resulted in widespread rollerballing but no new avalanches. This could help mute activity on Tuesday or indicate that slopes are ready to destabilize with additional solar input.

Those warm temperatures should stick around as clouds dissipate, leaving us with a bright, sunny day on Tuesday. That bumps wet loose avalanches to the top of the problem list, but some uncertainty remains. Will Monday’s warm temperatures help keep the wet loose problem in check at lower elevations? Is the sun strong enough to affect the snow on aspects such as East or West? Will any slabs fail on weak snow?

Expect to find 1-1.5 feet of snow above the EFC at mid to upper elevations. Depending on your aspect and elevation, the structure may look slightly different. Sun crusts on slopes that typically see direct sunshine have created crust sandwiches or may have melted into the EFC. Weak facets could be interspersed in the recent snow on shaded slopes, including right on top of the EFC. The surface will likely already be moist from Monday's warmup at lower to mid elevations. 

Travel conditions have improved significantly around the zone, but natural hazards such as open holes/creeks or exposed rocks/bushes still exist, particularly at lower elevations. 

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