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

Light and fluffy new snow sits over a firm surface in most locations, making it easy for a human to trigger an avalanche running under or within the new snow layer, which will be most reactive in the morning. More than 6 inches of overnight snow will increase the storm layer and size of subsequent avalanches. Avoid steep slopes on Saturday and let the storm snow settle.

Avalanche problems

  • Storm Slabs

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

    Your primary avalanche concern is storm slab avalanches failing with a human trigger on steep slopes on Saturday. Earlier in the day, snow will likely be more reactive before it has a chance to start adjusting.  Avalanches could occur beneath the new snow layer, which will likely be 1-2 feet deep. They could also fail within the storm layer,  closer to 6 inches deep. We expect most steep slopes to avalanche with a human trigger, although locations with wind-drifted snow will likely produce larger and more dangerous avalanches. 

    To start out your day, avoid slopes steeper than 35°. Evaluate the new snow/old snow interface and storm layers for bonding, and use small test slopes. If you see layers that slide or any other signs of instability like recent avalanches, whumphing, or long, shooting cracks stay off steep slopes. Steer around steep slopes where you identify thicker wind-drifted deposits all day. 

     

     

    (3/11/2023)

    Storm slab avalanche with wide propagation around a gully in Swift Creek/West North

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    Photo: Pete Durr

Avalanche Discussion

We've received around a foot of snow in the West Central zone since Thursday, and another 6+ inches is forecasted for Friday night. We're set up in a convergence zone which may or may not eventuate on Friday night, precipitation amounts may vary widely. If we get more or less snow than forecasted, the avalanche forecast may be less accurate so be sure to evaluate conditions as you travel. We lack information from the West Central zone, but in the zones both to the north and south on Friday avalanches failed beneath the new snow layer, around a foot deep, but some smaller avalanches were also reported as failing within the new snow layer, around 6 inches deep.  

A thick crust is present beneath the old snow surface in all areas aside from upper elevation northerly aspects. The only place you won't find that crust is the spots where you'll find a weak, faceted layer of snow that formed in those cold, shady, locations during our long period of high pressure in the last week. On those slopes, you may find even more reactive slab avalanches. You may be able to trigger small dry loose snow avalanches in non wind-affected areas on steep slopes. If the sun pokes out, which is most likely during the morning, small wet loose avalanches could occur as well. 

In the last week of primarily warm, sunny weather we've seen a constant trickle of wet loose avalanches, and an occasional larger slab avalanche or glide avalanche. Many of these wet snow problems have dissipated with the cold temperatures but not all yet. Continue to treat glide cracks and cornices warily, and avoid being anywhere near them. The old snow layer could be smooth or could be very bumpy, with old refrozen wet avalanche paths or debris piles hidden by the new snow. You'll likely find irregularities with your feet or sled, however, so travel very carefully. 

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