Bulletin d’avalanche

Mt Hood

Northwest Avalanche Center
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Danger d’avalanche

Wed
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

Heavy rain, snow, and wind-loading may cause natural avalanches overnight Monday with dangerous conditions lingering through Tuesday. Be leery of all slopes 35 degrees and steeper, especially those where you find fresh wind drifts or wet snow. Give the snowpack time to adjust and choose simple terrain away from the runout of large avalanche paths.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1.5–2.5

    Another foot of snow over the next 24 hours will bring snow totals since 3/12 to over 2ft at upper elevations. The bulk of precipitation falls warm and wet overnight with a strong cooling trend Tuesday. SW winds up to 50mph will redistribute the snow into the thickest and most reactive slabs in leeward terrain near and above treeline. Avalanches could break easily on a variety of storm layers. Even in non wind-loaded areas, you could easily trigger a slab avalanche large enough to bury or kill you in steep, unsupported terrain. Cautious route-finding and conservative decision-making will be essential. Only venture out during the storm if you are confident in your ability to identify and avoid avalanche terrain.

    (3/13/2022)

    Shooting crack in wind-drifted snow on an east aspect in Sand Canyon near 6200ft. 

    Photo: Andrew Kiefer

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2

    A wet loose avalanche cycle below treeline is already underway, and heavy rain up to 6500ft overnight Monday will only make matters worse. The most dangerous wet avalanche conditions will exist in the morning hours and fade as temperatures cool by Tuesday night. These avalanches could gouge into the snowpack and entrain significant snow as they run downslope. Watch for rollerballs and pinwheels as signs of wet and weak snow surfaces, and steer away from steep slopes during periods of rain. Even though these avalanches may start small and run slowly, they could grow large as they move downslope and create nasty debris piles. 

    (3/13/2022)

    A ski cut produced this small loose wet avalanche below treeline Sunday.

    Photo: Ron Martin

Avalanche Discussion

A weak atmospheric river will impact the region over the next 24 hours. Although this AR isn't as powerful as others we've seen this winter, it will still bring the heaviest precipitation yet since active weather began Saturday. The highest precipitation rates and most dangerous avalanche conditions look to occur overnight Monday with high elevation snow and rain below. We expect some large natural avalanches, even into the early morning hours. As snow levels drop from 6500ft to 3500ft by Tuesday afternoon, wet avalanche issues should end and several inches of cold snow could accumulate below treeline.

Poor visibility has limited observations above treeline since the storm series began. Near and below treeline, human triggered wind slabs and storm slabs 6-12in deep were reported Saturday and Sunday. Warming temperatures and rain also caused several small wet loose avalanches, with widespread wet activity below treeline Sunday. All recent avalanche activity has failed at or above the old/new snow interface buried 3/12, and we do not expect avalanches to break deeper in the snowpack on old snow layers moving forward. 

Régions couvertes