Bulletin d’avalanche

Mt Hood

Mar 18 – 19, 2019Northwest Avalanche Center
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Archivé · expiré 8 years ago

Danger d’avalanche

Wed
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
2 · Modéré
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Points saillants

The Mt. Hood area is undergoing a rapid spring transition, creating the potential for powerful wet snow avalanches as the warm and sunny stretch continues. East winds will locally cool snow surfaces, focusing the wet snow concerns on sunny, wind-sheltered slopes. As the day progresses, avoid steep sunny slopes with wet surface snow while thinking about your overhead exposure.

Problèmes avalancheux

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1

    Mid-march sunshine and warm temperatures are affecting a large swath of the compass during this dry and mild stretch, i.e. it’s not just steep southerly aspects these days. As the day progresses and temperatures warm, monitor changes in the upper snowpack, looking for natural pinwheels or small loose wet avalanches as clear signs of increasing danger.

    As the loose wet hazard increases, change your aspect and avoid similar slopes. Be especially cognizant of the consequences of even small avalanche around terrain traps like gullies or cliff bands.

    We have removed this problem from the above treeline terrain because winds have been preventing melt from occurring.

  • Wet Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely
    Taille
    1

    Is there enough meltwater entering the snowpack for a wet slab avalanche to occur? We don't know. We do know another day of sunshine and above freezing temperatures will increase the likelihood of this dangerous avalanche problem.

    You will want to steer clear of parts of the mountain that don't see the cooling effects of moderate east winds (think wind sheltered canyons for example). Large and dangerous avalanches may occur in isolated areas during Moderate danger.

    You may not see direct signs of instability prior to a wet slab release. As the day progresses, deal with the uncertainty surrounding this dangerous and hard to predict avalanche problem by avoiding terrain where avalanches can start, and limit your exposure to where avalanches can run or stop.

Discussion

Snow and Avalanche Discussion

Another day of high freezing levels with sunny skies is forecast for Tuesday. However, east winds will maintain in the moderate to strong range, locally dampening the loose wet avalanche potential on wind-affected slopes. Above treeline areas are expected to have experienced a moderate refreeze on Sunday night and they are expected to receive at least a shallow refreeze Monday night.

Small loose wet avalanche activity was observed below treeline on Mt. Hood on Monday, with winds cooling the snow near and above treeline. Don't let the minimal recent avalanche activity lull you into a false sense of security. The snowpack is undergoing a spring transition this week. Keep typical spring concerns on your mind. Important considerations include wet snow, cornice falls, and timing your travel with progressively warming snow surfaces.

Snowpack Discussion

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