Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

While this mild weather continues, larger triggers like cornice fall may still unleash deeper and more destructive avalanches in isolated areas. Continue to use caution in any terrain where you find punchy, wet snow.  Stay off of very steep or extreme terrain features where a small wet loose avalanche could cause injury.    

Problemi valanghivi

  • Loose Wet

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

    We have the same avalanche problem for Sunday that we've had for the last few days - wet loose - but in a slightly different flavor to close out the weekend.  With mild temperatures and cloud cover expected overnight and Sunday,  the potential for wet loose avalanches will creep around the compass and may include more northerly aspects.

    You'll likely see plenty of evidence of roller balls or wet loose avalanche activity on steep slopes from the last few days, you're unlikely to encounter new natural wet loose avalanches as a warning sign of increasing instability.  Right off the bat in the morning, you'll want to avoid extreme terrain features and terrain traps anywhere you find wet punchy snow.  Where those 2 pieces overlap, even a small slide can do real damage.  

    (3/18/2023)

    Rollers and small wet avalanches low on the south slopes of Herman.

    You'll want to stay off very steep cliffy/treed terrain like this where you find wet, punchy snow. 

    Photo: Matt Lubar

  • Cornices

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1.5–2.5

    The risk of cornice fall will remain elevated following a second night with a poor refreeze.  While cornices are a hazard in their own right, you need to keep cornice fall and any other sort of larger trigger (snowmobile, natural wet loose avalanche) on the forefront of your mind as the necessary ingredient to trigger a deeper slab avalanche.  We know of a few slab avalanches that released on Saturday; a 2' slab that released off of Mt Sefrit that was triggered by a natural small wet loose, and several very large (2-6') deep slabs triggered by Mt Baker Pro Patrol during avalanche mitigation Saturday morning. 

    While these events are likely to remain isolated, the consequences of getting caught in a deeper slab releasing down to the 3/10 interface (see below) would likely be unsurvivable.  Factor in an extra margin of safety and give avalanche path runouts, especially those with large overhanging cornices extra space until we exit this extended stretch of mild weather.  If traveling along ridgelines, assume cornices are weakened and give them a wide berth.  We haven't heard new reports of glide cracks opening, but if you see the brown frown of exposed rock, use the same technique of putting extra space between you and the slope in question. 

    (3/4/2023)

    Example from a few weeks ago of a large cornice triggered avalanche on Table Moutain. North at 5000'. 

    Photo: Jason Speer - Baker Mountain Guides

Avalanche Discussion

On a beautiful, warm and sunny Saturday, backcountry users reported many small wet loose avalanches and rollerballs on sunny slopes as surface crusts quickly broke down in the morning. Deeper avalanches were reported in isolated areas (noted above in the cornice problem description).  

A few slab avalanches from earlier this week ran on layers deeper than just surface snow. On Wednesday, a skier sustained serious injuries after being swept off of a cliff by a 2ft deep avalanche on Slate Mtn in the Baker backcountry. You can read the preliminary report HERE. On Friday, Lee Lazzara visited the site of the avalanche involvement and found that the slide ran on a slightly weaker layer of snow above a crust that formed on March 10th. On the 14th, a very large, deep slab was triggered during avalanche mitigation work (The last photo in the gallery below) in extremely steep, unsupported terrain. 

You may still see evidence of numerous wet loose and slab avalanches to D2 that were reported last Tuesday and Thursday. This followed a storm cycle that brought strong winds, 4" of water, and several feet of heavier, wetter snow early last week. 

Regioni coperte