Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Avalanche danger will peak Saturday morning before snowfall tapers off midday. Limit your exposure to avalanche terrain at upper elevations. Areas of increased danger may exist where snowfall is greater than forecast or lasts for longer. Be on the lookout for barely filled-in creek holes and other obstacles uncovered with heavy rain last weekend.

Avalanche problems

  • Storm Slabs

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

    Another round of snowfall overnight means the types of new snow avalanches observed today in neighboring zones could happen again tomorrow. There may be fewer natural avalanches but the general setup is the same - 4-8" of snowfall into the morning with winds strong enough to transport snow. You are more likely to trigger avalanches on slopes with recent wind loading but consider all steep terrain as suspect until proven otherwise. When in doubt default to lower angle slopes. 

    Keep an eye on new snow and wind slab layers using simple tests - hand shears, test slopes, skin track tests, etc - and adjust your plan based on what you see. The easier the new snow slides on the layer below, the more likely it is you will trigger an avalanche in steep terrain. Shooting cracks and recent natural or human triggered avalanches are explicit signs of continued instability. Heavy, wet snow at lower elevations could make for challenging travel and also produce rollerballs or even small loose wet avalanches.

    (12/30/2022)

    Crown of a slab avalanche that released within new snow layers. A south aspect on Herman in the Baker Backcountry at ~4700'.

    Photo: Kameron Decker Harris

Avalanche Discussion

Remote weather stations in West Central reported 0.5-1.0” of water with the latest storm - which roughly translates to 5-10” of new snow near treeline. Numerous natural and human triggered avalanches to D2 were reported Friday in West North and Stevens Pass. Storm and wind slabs were very reactive and had wide propagation. Some were triggered from below. Slightly more benign conditions were reported from Snoqualmie Pass and West South which received less snowfall and avalanche danger was limited to wind-loaded terrain and/or loose wet avalanches at low elevations.

The 6-10” of rain from December 23rd through the 27th reshaped the winter landscape at and below the snow surface. The existing snowpack was basically reset as a deep layer of wet grains now topped by snow from recent storms. Large creek holes and other oddly shaped terrain features opened up with the rain. Rocks and other objects melted out and were then barely covered with new snow. Use caution in poor visibility and when entering rollovers and other undulating terrain features. It’s going to take more than a few storms to fill in some of the bigger holes that formed during the rain event last weekend.

 

 

 

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