Lawinenlagebericht

Mt Hood

Jan 21 – 22, 2020Northwest Avalanche Center
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Lawinengefahr

Thu
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

Dangerous avalanche conditions exist. The likelihood of triggering a large and dangerous avalanche will increase throughout the day and peak when snow turns to rain at most elevations on Wednesday evening. Avoid slopes steeper than 35 degrees and pay close attention to warming temperatures which will drastically increase avalanche hazard.

Lawinenprobleme

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1

    Wednesday’s avalanche problems will be dynamic and changing throughout the day.

    New snow will start to stack up Tuesday night and will fall on a melt-freeze crust that is widespread. It remains to be seen how well new snow will bond to the crust or if sensitive weak layers develop during tonight’s snowfall. Investigate the bond between new snow and the crust below using small test slopes. Look for signs that you could trigger avalanches in the storm snow like heavy snow above light snow, or cracks shooting through the snow. Late morning or early afternoon, as the warm-up begins, will be the most likely time to trigger a storm slab on slopes steeper than 35 degrees on any aspect.

    Near and above treeline, winds will be strong enough to rapidly build fresh and sensitive wind slabs on lee aspects. Wind slabs will build above the recent melt-freeze crust and may become large quickly. Look for blowing snow, fresh cornice development and cracks in the snow as signs that you could trigger an avalanche on similar slopes. Avoid leeward slopes steeper than 35 degrees especially midday as the temperatures rise.

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1

    As temperatures rise during the day Wednesday and snow eventually turns to rain below 6500’, loose wet avalanches will be easy to trigger. Pay close attention to signs of warming, such as rollerballs of snow, many trees beginning to shed snow or drip water. When you see these signs avoid slopes steeper than 35 degrees, especially when near cliffs, creeks and other terrain traps. Remember that loose wet avalanches are often surprisingly powerful and being caught in even a small on can be dangerous.

Discussion

A storm approaches Tuesday night and should lay down significant snowfall before turning to rain Wednesday afternoon/evening. Avalanche hazard will increase sharply as the temperatures rise. There is some uncertainty when the transition from snow to rain will occur, so pay close attention to signs of warming, such as rollerballs of snow, many trees beginning to shed snow or drip water. When you notice these signs of warming the avalanche hazard is about to peak, so avoid avalanche terrain.

(Click the Photos & Regional Synopsis tab above for some pics of a very large avalanche on the Newton Headwall from last week)

Snowpack Discussion

New Regional Synopsis coming soon. We update the Regional Synopsis every Thursday at 6 pm.

Clearing on Sunday offered the first look at the upper mountain after an active 10 days of weather. A very large avalanche was observed on the Newton Headwall. It likely occurred during the storm last week, but highlights continued uncertainty about the snowpack at upper elevations.

A very large crown around 10,000’ on the Newton Headwall of Mt Hood which likely occurred during the storm last week. Photo: Kevin Kayl

Debris from the Newton Headwall avalanche in Newton Canyon. Debris filled the valley floor and extends to 5000’! Photo: Nick Burks

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