Avalanche forecast

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Northwest Avalanche Center
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Avalanche danger

Sun
Alpine
4 · High
Treeline
3 · Considerable
Below
2 · Moderate
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Out of date — this forecast expired 5 years ago. You’re viewing past conditions, not the current bulletin.

Highlights

A potent storm will bring very dangerous avalanche conditions to upper elevations. You can trigger avalanches big enough to bury or kill you where the wind drifts thick slabs of snow. Stick to low-angle slopes and take time to assess the snowpack as this storm tests recently buried layers.

Avalanche problems

  • Wind Slabs

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

    Avoid leeward slopes 35 degrees and steeper, especially where the wind forms thick drifts and pillows. Be extra cautious on slopes where the snow slides easily (or you get sudden test results) on a stout crust about 2 feet below the surface.

    Avalanches will be largest and easiest to trigger above treeline. You may even find drifts in open areas below treeline. Use a probe or pole to feel for deeper drifts. Indicators of the danger are recent avalanches, cracks shooting through the snow, and wind transported snow.

    (12/8/2021) Long shooting cracks in freshly wind drifted snow. E at 5200ft Photo: Matt Primomo

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1

    You may be able to trigger avalanches on slopes steeper than 35 degrees where you find more than 1 foot of recent snow and enough continuous snow cover to produce avalanches. Look for hard over soft layering, cracks in the snow, and test slopes that slide easily. Expect that warming temperature Friday night through Saturday morning may form slabs in the new snow. Quick snowpack tests can be useful to assess if the snow could slide before you commit to steeper terrain.

    (12/9/2021)

    Quick, hand pits are a good way to look for instabilities in the upper snowpack or to check if the recent snow could slide.

    Photo: Adam Butterfield

Avalanche Discussion

Since about December 4th almost 2 feet of settled snow has accumulated over the most recent crust (formed in late November). Snowfall picked up late on Friday and you can expect another 1-2 feet of snow by the end of Saturday. Observers have reported varied test results and triggered avalanches on the late-November crust. The crust seems especially problematic where it's smooth and slick and less so where it has more texture. As the snowpack gets stressed from heavy snowfall, keep an eye on this interface. You may be able to trigger avalanches that break wider than expected on the crust. 

It's early season, and snow cover is still shallow. If you're sliding on snow at low elevation, watch for hitting rocks, logs, or open creeks. 

Uphill travel reminder: Check in with your local ski area this weekend regarding terrain access and parking updates. Closed ski areas often share a similar snowpack and avalanche hazard as the surrounding backcountry. You may also encounter other hazards like active avalanche mitigation, unmarked obstacles, snowmobiles, groomers, and other heavy equipment as ski areas prepare to open. Be prepared to make your own assessments and handle emergency situations.

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