Avalanche forecast

Snoqualmie Pass

Northwest Avalanche Center
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Avalanche danger

Fri
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

The storm totals might not catch your attention, but strong winds, a complex snowpack, and recent avalanches certainly should. You're most like to trigger a slide in wind loaded areas or rocky complex terrain. Seek out more sheltered, simpler, or treed slopes.  

Avalanche problems

  • Wind Slabs

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

    Significant winds from various directions likely formed slabs on a wide variety of aspects and features. By Thursday morning, most of the active wind loading will be over, and you’ll need to hunt for visual clues to figure out where local winds built new slabs. Textured surfaces, wind lips, and drifts all point toward potentially loaded slopes. 

    Wind slabs will be the most common higher in the terrain, in the tops of chutes, beneath cliffs, and along the sides of gullies. In some cases, these slabs might sit over a firm crust and trigger very easily. These slides could also act as a trigger for deeper persistent slab avalanches.

    (2/19/2025)

    A wind lip showing cross loading along a mid-slope features. These area great visual clues of possibly wind loaded slopes. 

    Photo: Trevor Kostanich

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1.5–2.5

    There are several older persistent weak layers in the snowpack. Each can and has produced avalanches. The most recent slides occurred on Tuesday and appear to have failed on the 2/13 interface. 

    Don’t expect the snowpack to give you obvious signs like shooting cracks and whumpfs. The ‘bullseye’ data is already there. Digging is the only real way to look at this problem. Given the variability in these layers, even that presents a challenge. 

    Avalanches will be most likely in shaded terrain where the weak layers seem more common and more well developed. However, some slides have failed on slightly sunnier aspects. Think about the consequences of a slope before stepping into large steep open areas.

    (2/18/2025)

    This very large natural avalanche released Tuesday afternoon. on the backside of Chair Peak. It's uncertain exactly which of the older snow layers failed in this slide. WSW, 5400ft, SS-N-D3-R2-O

    Photo: Zack Novak

Avalanche Discussion

A couple more inches of snow and stronger winds Wednesday night should quickly draw to a close. By Thursday morning, we should start to enjoy a relative break in the storm train. The big question is the sky. While a few sun breaks seem likely, it doesn’t appear like Snoqualmie will see appreciable clearing. So while there may be rollerballs or a few small wet loose slides, they should stop short of developing much of a hazard. These slides should only involve the most recent snow.

However, on Tuesday skies cleared more than anticipated, and numerous wet loose slides released. Some even triggered deeper persistent slabs failing on the 2/13 interface. One of these avalanches was quite wide and deep (D3)!

Persistent Weak Layers: here’s a general summary of the current layers of concern.

  • 2/13 interface: Often a crust on more southerly aspects with rimed grains above On sheltered shaded slopes, surface hoar has been noted along with rimed snow grains. Most of the recent activity occ
  • January Drought Layer (JDL): Typically confined to shaded slopes. Facets sometimes with a thin crust. 
  • 1/10 Complex: A thicker layer comprised of larger facets and thin crust. 

At lower elevations rain and wet snow likely formed a crust. In some places, this could be thicker than others. This should limit but not eliminate the persistent slab issue lower in the terrain.

Regions covered