Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Tue
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Avalanche danger will increase throughout the day Monday as and another round of rain, wind, and snow further stress the snowpack. Expect avalanche activity during periods of heavy precipitation. Minimize your exposure to overhead hazard and avoid open slopes 35 degrees and steeper.

Avalanche problems

  • Loose Wet

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

    Snow and rain will continue over the next 24hrs with the bulk of precipitation expected during the day Monday (5000ft snow levels). Natural and triggered wet avalanches could occur in all elevation bands. The greatest wet avalanche hazard will exist Monday morning and early afternoon before temperatures cool in the evening. Avoid steep slopes during periods of heavy rain. Wet loose avalanches could entrain significant snow and grow large.  Glide avalanches are not out of the question either, especially in areas where shallow snow covers smooth rock. Choose conservative terrain away from large open slopes where you encounter a wet and unconsolidated snowpack. 

    Example photo of large wet loose avalanches on Table Mountain in the West North zone earlier this December.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2

    Another 8-12in of new snow is forecast at upper elevations in the Mountain Loop area by late afternoon adding to the already impressive storm totals over the past week (3-5ft). You can trigger large avalanches within new snow on open upper elevation slopes greater than 35 degrees. The thickest and most reactive slabs will exist in wind loaded alpine terrain. Avalanches are most likely to involve the most recent 24hr snow but may break deeper on various storm layers from the past few days. While weaker snow above the 12/9 crust (buried 4-5ft deep) is showing signs of healing in some areas, incoming snow each day continues to stress the snowpack and keep this layer on our radar. We are in the midst of a very active avalanche period with numerous reported avalanches each of the past several days. Monday will be another day to dial it back and seek out supported and lower-angled terrain. Be prepared to make observations as you travel and investigate the snowpack carefully. Use small slope tests and hand pits to observe the recent snow and determine which layers are most sensitive to triggers. 

    (12/16/20) Snowboarder triggered avalanche (D2) on a northwest aspect near 4500ft on Grouse Ridge in the West North zone. Crown height up to 18in. Photo Tristan Demers

Avalanche Discussion

Avalanche hazard likely peaked overnight Saturday in the West Central zone during the highest precipitation rates. Several large natural and triggered avalanches (D2-D3) were reported in the adjacent Mt. Baker and Stevens Pass areas failing within recent snow and deeper on older layers. Monday will bring another round of snow, wind, and rain. The snow conditions and avalanche problems will be very different at low and high elevations. Be prepared to make observations as you travel and choose lower angle terrain if you see recent avalanches, or experience shooting cracks or collapses. In nearby zones (Stevens Pass, East North/Central) weak persistent grains formed and were buried over the past week. A high degree of uncertainty exists surrounding this potential layer in the West Central. If you dig a snow profile, look for small sugary facets or feathery surface hoar about 4” (10cm) above the prominent 12/09 crust. If you travel at mid and upper elevations, consider limiting your exposure to large avalanche terrain where this layer might live.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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