Avalanche forecast

West Slopes Central

Northwest Avalanche Center
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Avalanche danger

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Out of date — this forecast expired 4 years ago.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

Highlights

Wind slabs both new and old can be found on a variety of aspects. Identify and steer around steep features with wind drifted snow to reduce the risk of triggering an avalanche. Assume a higher level of danger including and south of the Mt. Loop as that area received significant new snow. Look out for wet avalanches during periods of sun or warming. Check the forecasts for Steven Pass or Snoqualmie Pass if you are traveling adjacent to those zones.

Avalanche problems

  • Wind Slabs

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

    You will find wind slabs on a variety of aspects Tuesday. Day-old slabs from northeast winds are scattered about at treeline with more and deeper slabs in alpine areas. These are becoming stubborn to trigger, but be wary of steep, unsupported terrain features where you suspect wind-drifted snow. Another round of snowfall overnight Monday into the morning and moderate winds could build fresh slabs on slopes that were previously scoured down to the crust.

    While wind drifted snow was previously easy to identify, it’s going to be more difficult on Tuesday with new snowfall and periods of reduced visibility. Note areas where there is crust close to the surface (wind-scoured) versus where you are moving through deeper snow (wind-loaded). You are definitely traveling in wind slab when your skis or other floatation is getting stuck in a layer of softer snow below a more dense layer. Hand pits and test slopes can help you gauge the bond of wind slabs, but don’t ignore obvious signs of instability like whumps, shooting cracks, or recent avalanches. When in doubt simply avoid steep, wind-loaded terrain.

    (4/11/2022)

    A test slope produced a shooting crack on a south aspect at 5100'. This quick profile shows where the wind slab released over weaker snow below. The melt-freeze crust is the product of strong sun and warm temperatures on April 6-7th.

     

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–1.5

    If you are traveling in the southern reaches of West Central expect to see deep new snow out of wind affected terrain at lower and mid-elevations. Though the new snow layers should bond quickly, be patient approaching steep slopes and investigate how well the new snow is bonded before committing to avalanche terrain. Slabs of new snow could also become more reactive with warming as a denser slab forms over colder and weaker snow below.

    With the transition to spring, wet loose avalanches are also possible as cold snow warms and becomes wet on sun exposed slopes. Move off and away from terrain where you see rollerballs or small wet loose avalanches during sun breaks or with rising temperatures. Wet avalanches pack much more of a punch than their dry loose cousins and you just don't want to be in the way no matter how small they look. Even a small avalanche could carry you over a cliff or into a terrain trap.

Avalanche Discussion

Strong, easterly winds were reported across the North and Central Cascades Monday. Despite plenty of wind redistribution near and above treeline, minimal avalanche activity was reported. Aside from small avalanches triggered with control work in Stevens Pass, a single large slab avalanche was spotted high on Shuksan which was probably the result of rapid wind loading. Test slopes and other tests produced mixed results with some being quite reactive while others would not even produce cracking.

At treeline there is 30cm of wind-loaded snow over the melt-freeze crust on leeward slopes. Many windward slopes are scoured down to the crust. At lower and mid-elevations, the storm snow from early April has mostly transitioned to a mix of melt-freeze crusts, melt forms, and moist rounded grains,

 

 

 

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