Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Sun
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
3 · Marcato
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In sintesi

The snowpack will struggle to re-adjust after an amazing amount of rain at low elevations and snow at higher elevations over the last 2 days.  Large and destructive dry snow avalanches may release from higher elevation start zones. We will still be in the window for powerful glide/wet slab avalanches at lower/mid elevations.  Keep it simple and limit your exposure to large avalanche paths wherever you travel Saturday.  

Problemi valanghivi

  • Storm Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    It's likely several feet of dense snow accumulated above treeline over the last few days with much deeper drifts on lee slopes.  Continued significant new snow is expected through early Saturday morning before precipitation tapers.  Until the snowpack has had time to settle, you'll want to avoid big terrain capable of producing large avalanches until the snowpack stabilizes.  If you're traveling along the flats or valley bottoms, be aware of the terrain overhead.  It's less likely you'll see natural avalanches on Saturday than during the storm, but if one breaks deep into the recent storm snow, it will be large and dangerous.  Leave a large margin of safety on your uphill and downhill routes. 

    An older image of a large, destructive slab avalanche, which we expect to be continuing to happen at higher elevations as the storm continues. 

    Photo: Pete Durr

  • Wet Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    2–3

    Temperatures have started to drop as of Friday evening but the heavy precipitation rates just keep on coming.  It will be a smorgasbord of wet snow problems at mid and lower elevations on Saturday.  

    Wet slab and glide avalanches are notoriously unpredictable, with changes happening out of sight in the snowpack over time as free water moves through the snowpack.  There's a lot of water weight in the snow and any avalanches that do release could be very large and destructive.  They typically cannot be directly correlated to the most intense/warmest part of a storm cycle.  They should be less likely on Saturday as the weather quiets down but they should still shape how you travel.  Avoid lingering near or below large avalanche slopes in general and especially those with smooth bed surfaces and/or "brown frowns of glide cracks" until we enter a prolonged cool period and the snowpack stabilizes. 

    Wet Loose: You may see evidence of a natural wet loose cycle from earlier in the storm as temperatures rose and snow changed to rain.  Natural wet loose avalanches should be trending toward unlikely after several days of rain and warm temperatures.  However, if you are on a long steep slope, you might be able to trigger a wet loose avalanche that picks up steam further downhill.  Use extra caution around terrain traps where even a small avalanche could cause injury. 

     A large debris pile from a natural avalanche on Mt Herman which occurred during a storm on 1/12/21, exactly 2 years ago. These huge debris piles are probably very similar to ones that we'll see after this storm passes through: very large, and not something you'd want to get caught up in.  Photo: Trevor Konstanich

Avalanche Discussion

We have very limited information following our deluge.   About 7" of water was recorded at the Mt Baker station since early Thursday morning and the rain line likely rose to at least 6500' during the peak of the storm, perhaps higher.  We'll see significant new snow and wind above 5000-5500' tonight before the weather eases off the gas tomorrow.  Help us get a handle on what happened during the storm cycle and let us know what you see if you're out in the backcountry this weekend.  

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