Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Wed
Alta quota
2 · Moderato
Limite del bosco
2 · Moderato
Sotto il limite
2 · Moderato
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In sintesi

Large, firm wind slabs keep us out of wind-loaded start zones. They may be less likely to trigger, but humans or cornices might trigger them on a steep rollover. At lower elevations, move to shaded aspects as surface crusts melt, increasing the risk of wet avalanches.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2

    A period of extreme winds and significant new snow Thursday through Saturday morning built large wind slabs. Additional wind transport likely added to the slabs on Sunday. Warm temperatures and time have helped these slabs to become more stubborn to trigger. If triggered, slabs are likely to be firm and several feet deep.  Look for recent cornices, stiff and textured snow surfaces that may crack under your feet as you travel. Where you see these things, navigate around wind-loaded slopes steeper than 35 degrees. Use caution not to travel above wind-loaded convexities such as the one pictured.

    (3/1/2021) Large explosive-triggered wind slab on a steep slope above treeline.

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Cooling temperatures, wind, and surface crusts will be battling against the March sunshine on Tuesday. Overall, we expect wet loose activity to diminish relative to Sunday. Wet loose avalanches are most likely on wind-sheltered aspects directly facing the sun.  If it feels warm outside, the snow probably experiences the same. Most wet avalanches will be small, but in isolated cases, snow could entrain deeply an become larger. Pay attention to fresh rollerball activity and snow you can sink into above your ankle as surface crusts break down.  If you see these clues, choose lower-angle terrain and shadier slopes. Use extra caution above terrain traps like cliffs and creeks.

    Example: Rollerballs entraining sticky snow near the surface. Photo: Ashley Turcott.

Avalanche Discussion

A number of natural and human-triggered avalanches and a large explosive-triggered avalanche occurred on Monday. These avalanches remind us that we're still on the tail of a major storm and avalanche cycle featuring 50 inches of snow since 2/22 along with extreme winds. That snow sits above a freezing rain crust up to roughly 7000'. A snow profile adjacent to the Hinterlands Avalanche at Mt. Hood Meadows shows a 40" slab above weak snow grains sitting on the freezing rain crust. These weak grains are healing and avalanches are unlikely at this interface moving forward.

Mild temperatures Monday created significant rollerball activity below treeline and likely wet loose avalanches. The milder temperatures should have helped to accelerate the healing process for large wind slabs above treeline, but given the extreme winds, the size, and recent avalanche activity, we're still concerned about human or cornice-triggered wind slabs.

During the ongoing Covid-19 pandemic, continue to follow the latest guidance from local, state, and federal health officials. Avoid unnecessary risks that could impact first responders and stress medical resources.  Wear a mask when appropriate, practice social distancing, and consider recreating closer to home.

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