Boletín de aludes

Mt Hood

Northwest Avalanche Center
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Peligro de aludes

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

Lo esencial

You may easily trigger a slab avalanche on steep slopes tomorrow.  You’ll find the largest slabs near and above treeline where the wind will deposit new snow onto east-facing terrain.  Avoid areas being actively wind loaded and give cornices a wide buffer.

Problemas de aludes

  • Wind Slabs

    • Alta montaña
    • Límite del bosque
    • Bajo el límite del bosque
    Probabilidad
    Likely
    Tamaño
    1–2

    Strong southwest winds along with 5-10 inches (.50-.75 in swe) of new snow will build reactive wind slabs that could be up to 1-2’ deep.  These areas of wind blown snow will be most reactive during the morning hours corresponding with the heaviest precipitation rates and highest winds.

    You will find the largest slabs living on the east side of ridges, below cornices, and at mid and upper elevations.  Strong winds and limited visibility should be enough of a sign for you to choose lower angled, sheltered terrain. 

    Below treeline, significantly smaller slabs will form, however, they could still be large enough to ruin your day in the wrong terrain.  Many below treeline areas developed a layer of weak snow at the surface due to recent cold and clear nights.  If this weak surface snow stays intact despite the strong winds, expect the new snow to bond poorly to the old snow surface.  Thursday will be a great day to use small test slopes and hand pits at lower elevations as a way to gauge how easy the snow will slide. 

    (12/3/2022) A shooting crack in a wind-loaded pocket. One of the red-flag signs of instability that shouldn't be ignored. Photo: Dallas Glass

Avalanche Discussion

After a few days of quiet weather, observers found a mixed bag of conditions across the zone.  On many  lower elevation slopes, cold evening temperatures paired with clear skies developed a layer of near-surface facets and surface hoar.  On steep southerly aspects, a thin sun crust formed on 12/6.  Above treeline, steady northwest winds sculpted variable surfaces, such as sastrugi on exposed ridge tops and areas of firm wind-blown snow. 

Once the new snow starts piling up, it will be critical to assess how the new snow bonds to the pre-existing surface.  Thursday will be a good day to simplify your terrain choices and avoid steep wind loaded slopes.  

Thanks for some of the public observations this past week!  If you get out , please submit an observation on our public observation platform!  These observations play an integral role in producing a quality avalanche forecast, but also help the greater backcountry community.

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