Boletín de aludes

Mt Hood

Northwest Avalanche Center
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Peligro de aludes

Wed
Alta montaña
3 · Notable
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

Conditions remain dangerous at upper elevations following a large dump of snow and 48 hours of consistent wind transport. Fresh, sharp wind lips on ridgelines, active snow transport, shooting cracks, and recent avalanche activity all serve as reminders to avoid steep wind-loaded slopes. Below treeline, there's enough snow to travel, but shallowly buried obstacles remain the primary concern.

Problemas de aludes

  • Wind Slabs

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

    Unrelenting moderate and strong winds since late Saturday continue to redistribute the 21" of storm snow (and counting). Winds will decrease on Tuesday with a brief break in snowfall. Therefore, your risk of triggering an avalanche may be highest at the start of the day, but some wind transport is expected to maintain dangerous conditions with large avalanches easier to trigger at upper elevations. More specific wind-loaded slopes near the treeline were reactive at Timberline on Monday, and we think wind slabs remain reactive, but slightly smaller in size at mid-elevations Tuesday. Monday's evidence of widespread and active wind transport, shooting cracks in wind-loaded terrain, and a small intentionally triggered slab (pictured) should have you on your guard. Dial back your terrain selection if you encounter similar "red flags" on your outing.  Take advantage of safer travel on ridges or windward slopes.

    We're just approaching the depth threshold for avalanche activity below treeline. Maintain your awareness and remember that if you find wind loading at these elevations, you can still trigger a small avalanche.

    (12/27) Intentionally triggered soft slab just above the Timberline parking lot. 

    Photo: Joe Dellaporta

Avalanche Discussion

On 11/28, NWAC forecaster Joe Dellaporta enjoyed his first professional field day with NWAC. Within a stone's throw of the Timberline parking lot, he encountered unstable snow, intentionally triggering a small (D1) 8-10" soft wind slab . He found 20" of storm snow on average. The snow fell on a cooling trend, but active and recent transport (illustrated by wind ripples) destabilized the snow with drifts 2-3' deep. Shooting cracks served as an additional reminder that a fracture would propagate across any nearby sufficiently steep slope, producing an avalanche. Fresh and visibly growing wind lips also served as a reminder of deposition on the slopes below and the actively increasing slab problem during the day.

A brief break in the weather Tuesday morning should enable some better visibility before light snowfall returns in the afternoon. Please let us know what you find if you have a look around.

Avalanches will not be your only challenge when navigating in the backcountry on Tuesday

  • Don't forget about the shallow coverage and the risks inherent to early-season travel. The new snow comprises most of the snowpack and lies above a variety of crusts, wind-affected snow, and bare ground which you can read about here. 
  • Cold-related injuries such as frostbite will be increasingly likely as the temperatures drop. Make sure you're prepared with extra layering in the advent that something goes wrong.

Before you head out the door, remember to check the Uphill Travel Policies of your local Ski Resorts.

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