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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Highlights

Stormy weather will linger into Friday morning and build fresh slabs on the lee sides of ridges and exposed features. Fortunately, blowing snow, fresh cornices, and sharp drifts should help you anticipate the wind-loaded pockets you want to avoid. Some of these slides could trigger easily and grow large enough to take you for a rough ride.

Avalanche problems

  • Wind Slabs

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

    While the snow totals from this storm aren’t that impressive, when you add in the strong winds, it's easy to see how it will make conditions more dangerous. Expect fresh slabs in some unusual locations thanks to the W-NW winds. In many instances, these wind-loaded pockets will rest on an underlying crust. This could allow them to trigger easily and travel quickly. Fortunately, the size and distribution of this problem will limit the hazard. You’ll typically find slabs below cornices, near the base of cliffs, in the tops of chutes, or along mid-slope gullies. While we expect these slides to stay relatively small, you could easily encounter 1ft deep crowns with enough snow to flush you down a couloir or over a cliff.

Avalanche Discussion

This storm should bring 6-8 in of snow to the mid and upper elevations of the Pass Thursday night and Friday morning. The bulk of the precipitation and the strongest winds occur in the morning hours; you’ll likely see the greatest avalanche danger during that same time. One question we have is how the new snow will bond to the old surface. Prior to this storm, you could find firm crusts, settled powder, and possibly surface hoar/facets on the top of the snow. Small slopes and hand pits should like you quickly test this bonding. 

With cooling temperatures, outside of wind-affected areas, the snow should be generally right-side-up. This could result in a few small sluffs in very steep terrain. 

The other big question is where will the rain snowline sit. We think it will be near or just above pass level. That means rain in the lower sections of the below treeline band. This could result in a few rollerballs or small loose wet avalanches, but generally, the lower elevation snowpack should easily handle the water without fuss. 

While the upper snowpack still contains several older interfaces (1/21, 1/18), it’s generally strong, well-settled, and should handle this new storm load. We expect any slide to break at or above the 1/26 interface. Prior to this storm, 1.5-2 ft of snow sat over the very stout and prominent MLK crust. Use this layer to target your observation on the upper snowpack.

Regions covered