Bollettino valanghe

Mt Hood

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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In sintesi

Shallow wind slabs will gradually form at upper elevations. As conditions become more winter-like, take note of the wind direction and steer around steep slopes in the lee of ridgelines. At lower elevations, rain may trigger very shallow wet avalanches on northerly aspects holding shallow dry snow.

Problemi valanghivi

  • Wind Slabs

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

    Moderate to strong winds will blow 2-3" of anticipated fresh snowfall onto lee slopes where temperatures are cold enough for effective wind transport, above treeline.  As you ascend in the terrain and the scene becomes more winter-like, note signs of active wind transport including blowing snow, fresh cornices, and wind-textured snow. Anticipate lee slopes, such as in the lee of ridgelines, where you might find more than 6" of wind-drifted snow sitting above a crust or old snow. Steer around these pockets on slopes steeper than 35 degrees.

    (3/16/2021) Example: Wind-textured ripples suggest the presence of shallow wind slabs that you can trigger near the entrance to steep, confined chutes and just below ridgelines.

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1

    Light rain may reach up to 6500 ft or so on Friday morning before temperatures cool later in the day. If snow falls on northerly slopes holding dry snow near treeline, shallow natural avalanches and rollerballs will follow on slopes steeper than 35 degrees. At lower elevations where Wednesday's crusts may not refreeze overnight, you can trigger shallow avalanches on slopes approaching 40 degrees if you punch through the crust. Danger may be heightened during bands of rainfall, however, these very small avalanches pose a problem primarily in high-consequence terrain such as around cliffs, rocks, or gullies.

    (3/12/2021) Small loose wet avalanches in White River.

Avalanche Discussion

A melt-freeze crust up to 1 cm thick exists on most aspects in the Mt. Hood terrain. An inch or two of snowfall from over the weekend remains cold on northerly slopes near and above treeline. Above freezing temperatures at all Mt. Hood NWAC stations allowed the crust to soften during the day on Wednesday. The warming did not produce avalanches, but an avalanche professional managed to get a very shallow loose wet avalanche moving on a steep slope. 

Snow and avalanche conditions begin to transition on Thursday as a new storm moves in. Wet Loose avalanche activity may be more of a problem in the morning, while wind slabs will build enough to become a problem later in the day. Pay attention to the conditions around you, if you find wet/sticky snow or active wind loading, choose less committing terrain.

The last major storm event ended on February 27th with drier conditions interspersed with light snowfall events through the beginning of March.  In the upper snowpack, you can still find a distinct freezing rain crust buried on 2/22.  This layer was the most recent interface for larger avalanche activity in the Mt Hood area towards the end of February and the first few days of March.  

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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