Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

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

MORNING UPDATE: The danger was lowered to moderate at all elevations. Intense snowfall late Thursday created the potential for small or large storm slabs or loose dry avalanches at all elevations. Manage these hazards by steering around steep, convex, and wind-loaded slopes, particularly first thing in the morning when the avalanche danger is greatest.

Problemi valanghivi

  • Storm Slabs

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

    High rates of snowfall tend to create instability that takes more than 24 hours to heal. Friday afternoon and evening saw 1-2"+ per hour snowfall rates for multiple hours under light winds. This snow sits on top of 4-5" of snow (redistributed by winds at upper elevations) which fell Wednesday night and sits on top of a strong rain crust. Expect widespread hazard on steep, convex slopes greater than 35 degrees. Monitor your slope angle. Use consistent small slope tests to confirm the problem and exercise the most caution early in the day when your danger is greatest and at upper elevations where the winds early in the storm drifted snow to form larger and more dangerous slabs.

    In many areas, the snow may remain unconsolidated. Dry Loose avalanches will run far and fast on the crust. Maintain awareness of objective hazards below you such as rocks, trees, or cliffs.

     

    (11/24/2020) A quick skin track test as you travel can show you the upper snowpack's slab potential.

Avalanche Discussion

Mt. Hood Meadows reported 9" of 8.6% density snow falling late Thursday into Thursday evening. This produced limited results in morning control and in most cases did not exhibit slab character, prompting us to lower the danger rating to moderate at all elevations and adjust the avalanche problem size to small-large.

Incoming snow bonded well to a refrozen crust following a week of warm, dry weather in early December. The crust should limit your avalanche danger to snow that fell since Thursday. With a good bond between the new snow and the crust, we expect avalanches to be triggered within mid-storm layers that are more challenging to predict. However, the crust provides an excellent bed surface for avalanches to run faster and farther than you expect. If mid-storm layers don't materialize on Thursday, expect loose dry avalanches that you can also trigger on slopes steeper than 35 degrees. These avalanches don't run cohesively, but may still swipe you off your feet and into terrain you might not want to be pushed into.

If the sun comes out on Saturday, steep south-facing slopes may also produce Loose Wet avalanches. If you observe rollerball activity, change your aspect toreduce your exposure.

On Friday, reports from Mt Hood Meadows suggested the presence of wind-affected snow above treeline, a shallow loose dry avalanche problem near treeline, and slightly heavier snow forming a more cohesive slab below treeline.

Regioni coperte