Boletín de aludes

West Slopes North

Northwest Avalanche Center
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Peligro de aludes

Wed
Alta montaña
2 · Moderado
Límite del bosque
2 · Moderado
Bajo el límite
1 · Débil
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Desactualizado: este boletín caducó 4 years ago. Estás viendo condiciones pasadas, no el boletín vigente.

Lo esencial

Light snow and moderate winds will give the mountains a bit of a refresh on Tuesday. Lookout for and bypass steep terrain with recently wind drifted snow to limit the chance of starting an avalanche. 

Problemas de aludes

  • Wind Slabs

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

    While avalanche danger from wind slabs shouldn’t increase with a few inches of snow and moderate winds overnight, it won’t exactly go down either. Older wind slabs from the weekend were observed as becoming unreactive. Small new slabs will continue to form until winds become calm in exposed terrain or there is no snow available for transport.

    Track the depth of new and wind drifted snow to find areas where fresh wind slabs developed. Stomp on wind drifted features to get a read on wind slab reactivity. Evaluate the bond of wind slabs before committing to steep terrain - or just find a lower-angled line around areas like convex rolls where you are more likely to trigger one.

    (1/23/2023)

    Shallow wind slabs triggered in steep terrain Monday. 

    Photo: NWAC Public Obs

Avalanche Discussion

Observers on Monday found recently wind affected snow and shallow, fresh wind slabs near and above treeline. In sheltered areas, the old/new snow interface was found 6” down. Few signs of buried surface hoar or facets were found but the interface in question still produces moderate results in formal and informal testing. Still, the pattern of avalanche activity currently doesn't show much of a problem. Sun breaks didn’t provide nealry enough warming on solar aspects to produce wet loose avalanches in observed terrain.

Reported avalanche activity on Sunday consisted of a single human triggered avalanche (D1.5) on a very steep, unsupported feature in wind loaded terrain (north @ 5000'). The rider was caught and partly buried in the terrain trap below. No injuries were reported.

The snowpack below recently formed wind slabs consists of alternating rounded grain and rain crust layers. Surface hoar and/or facet layers that produced avalanches earlier it the winter have become dormant and likely rounded out. The biggest question mark is if weak snow surfaces from last week were preserved under new snow in a few places. Take an extra minute or five to look at the interface between new and older layers before diving into consequential terrain. 

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