Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

Mon
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

A shot of new snow and strong winds will build slabs on downwind slopes. Avoid travel in steep terrain where you observe smooth drifts of wind transported snow. This will reduce the risk of triggering an avalanche until the new slabs have time to bond to the layer below. Sun breaks could produce rollerballs and loose wet avalanches - move away from steep slopes in the sun if you observe either.

Avalanche problems

  • Wind Slabs

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

    Stubborn wind slabs from the previous storm and fresh slabs of newly wind drifted snow should both be on your radar tomorrow. Strong winds and 6” of new snow by the end of Saturday were reported as just beginning to build new slabs in neighboring zones. Winds and snowfall will taper overnight but wind slabs will remain in play on Sunday. If you find more snow or stronger winds than expected then assume a higher level of danger.

    Pay attention to the pattern of wind loading by using scoured snow surfaces, cornice-like features, and changes in snow texture to figure out where wind slabs lurk. Stiff, smooth snow surrounded by rougher surfaces is probably wind slab. Upside-down snow is also a great sign that you have found a wind slab.  You can use test slopes and other tools to evaluate wind slab bonds or just steer around steep wind loaded terrain.

     

    (1/5/2023)

    Wind eroded snow surfaces are a tell tale sign of wind transport and possibly wind slab formation in nearby terrain.

    Photo: Ian Nicholson

Avalanche Discussion

While most of the west slopes should remain cloudy Sunday, we may see some sun breaks in West Central. Widespread wet loose activity is not expected but as usual, keep an eye on terrain overhead that is warming in the sun and producing rollers or very small loose wet avalanches.

Observers Saturday in West North found a big change in conditions from Friday with strong winds, extensive wind drifting, poor visibility, highly variable and temperature-thickened snow surfaces and an overall decline in snow conditions from the days prior.  Less challenging conditions were found in Stevens and Snoqualmie Pass with lighter precipitation and winds throughout the day.

A weak snow surface of light-density new snow, surface hoar, and facets was observed the past few days. Observations Saturday point toward these surfaces being warmed up and then destroyed by the wind prior to snowfall. In areas where weak snow survives and is buried intact, the old snow surface could make for new slabs that are easier to trigger or release in surprising ways. Identify and investigate the interface between new and older layers and ease into steeper terrain by starting with smaller, less consequential slopes. 

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