Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

An overnight burst of snow with wind will elevate avalanche danger, and it is likely that you could trigger an avalanche near and above treeline in the new storm snow. Avalanche activity is expected to be highest in the morning, although weather forecasts vary and danger may be higher or lower depending on our actual snowfall amounts. Steer around steep slopes while the snowpack settles, especially in areas with thicker, wind affected deposits where snow will be more reactive and resulting avalanches could be larger. 

Avalanche problems

  • Storm Slabs

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

    The majority of snowfall is expected in the early hours of the night, and  it's likely that you'll be able to trigger reactive storm slabs, especially at the start of the day Saturday. Locations with more than 6 inches of snow over the old snow layer, which is a crust in most spots, are where you can expect to trigger a slab avalanche. The underlying crust may provide a good sliding layer, producing faster and longer-running avalanches. 

    Moderate to strong winds, which have since backed off, occurred while the majority of snow fell as well. Locations with thicker, wind drifted snow are where you can expect it to be easier to trigger an avalanche, and the avalanche will probably be larger. New drifts may be subtly hidden beneath non wind-affected snow. 

    With a relatively shallow layer of new storm snow over an abrupt transition to the underlying crust, you can assess the new snow layer to see how reactive it is. Small hand pits to investigate the bond are applicable in this situation if you know how to do them. Checking small test slopes on skis or boards, snowshoes, or snowmobile works well also. In general, stay off slopes steeper than 35°. If you experience long, shooting cracks from your feet or sled, recent avalanches, or experience any other signs of instability, dial it back even more.   At lower elevations, avalanche danger is Moderate, which means avalanches are still possible but we expect the layer to settle quicker and bond better to the underlying layer. 

    Small avalanches failing in storm snow with a human trigger on a small test slope. You can use steep rollovers to see how reactive the new storm layer is. 

    Photo: Zack Mcgill

Avalanche Discussion

We're entering a period of typical spring storms, with intense bursts of snowfall and wind. Most of the 6 or so inches of snow is expected to fall before midnight, but we'll continue to see bursts through the early morning hours and much of the day, when we could be totaling around a foot by the end of the day.  A convergence zone is expected to set up in the Mountain Loop Highway, and more snow than forecasted may continue through the day. If more or less snowfall occurs than forecasted, the avalanche danger may be higher or lower than this forecast. 

Sun breaks are possible, and small wet loose avalanches could run if steep slopes moisten enough. The new low density snow could also run as a dry sluff on steep slopes as well. If you make it out into the West Central zone please submit an observation to let us know what conditions were like where you traveled. 

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