Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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

Avalanche danger will hinge on the strength of the snow surface on Saturday. Avoid moving across or below steep terrain if the snow surface warms dramatically through the day.  Identify and minimize time spent below cornices and other unstable snow features in steep or rocky terrain above you.

 

Avalanche problems

  • Loose Wet

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

    The avalanche danger on Saturday will most likely be determined by two factors. How much does the snow surface freeze overnight and how much sun comes out the following day? A cold night with a solid refreeze and lots of clouds tomorrow will make lower danger as the snow surface will stay strong and locked up through the day. A weak refreeze plus more sun than expected means for a weak snow surface and might even trigger a round of small natural avalanches on southerly aspects. Prepare to assess weather and snow surface conditions throughout the day. Move to simpler terrain if you witness recent signs of instability, avalanche activity, or are skinking past your ankles in wet snow - even with the assistance of skis or other floatation. 

    Example of a natural loose wet avalanche (D1.5) on a sun-exposed slope. Photo: Zack McGill

  • Glide Cracks

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1–3

    Observers on Friday reported numerous glide cracks and glide avalanches triggered by heavy rainfall earlier in the week. These avalanches occurred when the entire snowpack released on a smooth, steep ground surface below. Rain and meltwater lubricated and weakened the snow/ground interface to the point the snowpack could no longer hold in place. Glide cracks are areas where the slab is slipping on the ground but has not yet avalanched.

    The likelihood of more glide avalanches is very low with the end of rain and lowering freezing levels. It's difficult to say if these types of avalanches are really "Possible" since they are all isolated events by nature. Still, they have naturally released days after they were no longer thought to be a problem. This is especially the case with unsupported snow blocks hanging on the margins of the initial avalanche. Avoid traveling under sagging cornices, glide cracks, or areas where glide avalanches recently occurred. Give suspect terrain plenty of room and minimize the amount of time spent below if there are no other terrain options.

    (1/14/2022)

    Large glide avalanche or rock slab (just left of cetner) below Huntoon Point in West North. Note hanging blocks, hangfire and sagging cornice all surrounding avalanche release area.

    Photo: Lee Lazzara

Avalanche Discussion

Excellent visibility allowed for observations in adjacent zones. Glide avalanches, cornice fall triggered slab avalanches, loose wet, wet slab, and a very, very large slab avalanche high on Mt. Shuskan were reported. All were triggered during periods of warm temperatures and heavy precipitation earlier in the week. A round of natural loose wet avalanches with afternoon clearing was observed in steep southerly terrain above treeline on peaks north of Highway 542 in West North.

Wind transport of dry snow was observed at the highest elevations today. If you make it to the alpine on Saturday be on the lookout for small but unstable wind slabs in exposed terrain.

Telemetry across and adjacent to the West Central has recoded anywhere from 4.0” to 7.0” of precipitation from January 10th through midday on the 134th. It fell nearly all as rain except for at the highest elevations. The rain fell on a cold, dry snowpack near and above treeline and triggered a natural avalanche cycle across the Cascades consisting of loose wet, wet slab and glide avalanches.

 

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