Boletín de aludes

West Slopes North

Northwest Avalanche Center
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Peligro de aludes

Sun
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 3 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

The avalanche danger is low except in areas of wind drifted snow. Use lower-angle terrain to navigate around steep slopes where you observe active wind loading. Avalanche danger will slowly increase through the day. 

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Possible
    Tamaño
    1–1.5

    Strong winds and a few inches of new snow will build some smaller wind slabs. The question for Saturday is if the southerly winds will be strong enough to erode away the crust capping a foot or more of soft, dry snow below. If the crust stays intact then wind slabs should stay small and isolated. If the wind wins out then look for bigger and more widespread slab formation - and higher avalanche danger - as the foot of snow from earlier in the week gets redistributed onto leeward slopes.

    Areas of wind slab should be easy to identify - blowing and drifting snow will show where fresh, smooth-looking wind slabs are forming. They might be more reactive where they build over crusts or weak snow currently at the surface. 

    Slab avalanches releasing in new snow layers are still being triggered in wind loaded terrain (see discussion). There isn't really a way to distinguish where these still exist other than slopes greater than 40 degrees on northerly, wind loaded aspects.  

     

    Blowing snow points the way toward fresh wind slab.

    Photo: Zack McGill - Cascade Mountain Ascents

Avalanche Discussion

Two human trigger slab avalanches were reported from the Baker Backcountry on Friday. One was small in size (D1) and triggered on a short but very steep slope on a north aspect at 4900’. The other was bigger at D1.5 with a 6” crown. It was triggered on a northeast aspect at 5300’. A few new wet loose avalanches on southerly aspects were observed late in the day. Dry loose avalanches in steep terrain were observed to still run far. No observations came from other areas of West North

The biggest question mark in the snowpack is a layer of slightly weaker snow just above the stout rain crust that formed last weekend. It may be the culprit in slab avalanches that are still being triggered on slopes greater than 40 degrees three days after the last significant snowfall and wind. Though shallow they still show wide propagation and could be dangerous in consequential terrain.

Most aspects have some sort of crust topping the latest storm snow from Tuesday. Terrain greater than 20-25 degrees on northerly aspects at mid and upper elevations can still hold good snow - except where it’s been scraped down to the crust. Surface hoar and an inch of new snow are at currently found on top of crusts but it’s questionable how much of it will survive the sun Friday and then wind on Saturday.

On Wednesday numerous wind slab and wet loose avalanches were reported from across West North, naturally and also human triggered. Most were on the smaller side of things at D1.5 or less but a few were probably larger. All released at or above the crust interface buried by new snow Tuesday. Slightly older avalanches (D2.5-3) were also reported. Most are suspected of releasing during the big storm and rain event last weekend. 

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