Bollettino valanghe

Central Cascades

Central Oregon 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

On Saturday, avalanches will be possible in wet snow, especially at lower elevations like the Santiam Pass. Avalanche danger will increase during the day as temperatures warm well above freezing and rain begins falling in the afternoon. If you begin sinking into slushy snow, move to lower angle slopes and avoid gullies, tightly spaced trees, and other terrain features that can make a small avalanche worse.

Up high, watch for isolated pockets of wind deposited snow that could catch you by surprise. If you're unsure, stick to slopes that are less than 30 degrees.

Problemi valanghivi

  • Loose Wet

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

    Saturday will begin with some sun breaks in the morning and temperatures rising above freezing by mid-morning. Daytime highs will reach 40 F at 7500' and the mid-40s at the Santiam Pass. Rain will start in the afternoon and continue into the evening. As temperatures rise and rainfall hits the upper snowpack, the snow surface will lose cohesion and become slushy. As this happens, the wet loose avalanche danger will increase, especially at lower elevations.

    On Friday, I saw an increase of roller balls on east aspects around 8000' during the early afternoon. However, I did not observe any loose wet avalanches at this elevation band, nor did I hear any reports of wet snow instabilities near and above treeline. I think loose wet avalanches that are large enough to bury, injure, or kill a rider are unlikely at upper elevations, but given the forecasted daytime high of 40 F, it's worth keeping this problem in mind if you're venturing up high.

    If you find yourself in terrain where you begin sinking into slushy snow, it's time to back off to lower angle slopes. Loose wet avalanches on steep terrain can pick up speed and entrain additional snow quickly, and if you get caught in a terrain trap like a gully or tight trees, even a small avalanche can have serious consequences. 

  • Wind Slabs

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

    Wind slabs avalanches are becoming more stubborn, but isolated pockets of instability could remain, particularly in the alpine. Assess the snowpack carefully before committing to steep terrain that's been recently wind loaded. 

    Today, near the summit of Ball Butte, I dug into a wind slab on a north aspect and was surprised to see the top 30 centimeters fracture while I was just starting to cut a column. I went straight to an extended column test (ECT). I did not get propagation in a single loading step (the slab did eventually fracture across the 90-cm wide column, but then I had to really tug on it to get it to slide). I investigated the snow grains with a loupe and did not find any facets (weak, sugary snow) above or below the fracture.

    There was a report from yesterday at Broken Top, where riders on a southwest aspect found a wind slab sitting on top of a few centimeters of weak, sugary snow, which was above a crust. This type of snowpack structure is ideal for a slab avalanche. 

    While most observations in the past two days indicate that wind slab avalanches are now unlikely, there's enough uncertainty to give me pause. I think it's worth keeping this problem on the list for another day. 

    (2/21/2025)

    This column fractured, but not in a single loading step. I also had to tug it to get it to slide. 

    Photo: Allison Miles

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