Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Fri
Alta quota
4 · Forte
Limite del bosco
4 · Forte
Sotto il limite
3 · Marcato
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In sintesi

Freezing levels are forecasted to rise to a shockingly high 9500ft Thursday afternoon and wet avalanche activity will increase throughout the day. A lot of uncertainty exists as to how active the wet avalanches will become, so pay close attention to nearby steep slopes, and when you start seeing them coming down, shift your travels away from all avalanche terrain, including the runouts beneath large paths as avalanche conditions could quickly become very dangerous. This is a sudden shift after a large storm deposited about 5 feet of dry snow, and you could still trigger a lingering slab avalanche on wind-drifted steep slopes. 

Problemi valanghivi

  • Loose Wet

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

    Temperatures will rapidly warm on Thursday, and you can expect to see a sharp increase in wet loose avalanche activity as the day progresses. A thin crust formed on southerly aspect Wednesday, but the intense additional warming of Thursday will quickly melt through that crust and affect the underlying layers. Five feet of otherwise relatively low-density snow will quickly lose strength and wet loose avalanches will begin running. They will first occur as small point releases originating on steep slopes by rocks, but they are expected to increase in size and distribution as the day continues to warm. We do not expect that they will entrain the entire depth of the new storm snow, however it is not out of the question if it heats up enough and large amounts are entrained. 

    Uncertainty exists as to the extent of wet loose avalanches on Thursday. Avalanches may remain on south-facing slopes if it's mainly sunny, or they could wrap around the compass if cloud cover causes more even heating. It is up to you to monitor conditions throughout the day and gauge how fast the mountains are coming unglued. Given all the unknowns about the extent of natural wet avalanche activity, it’s probably best to play it safe. When the snow becomes wet and saturated or you see signs of instability like rollerballs and small wet avalanches then it's probably time to move to simple terrain with no exposure to overhead avalanche terrain. 

    A photo from last year in the Baker backcountry, showing a large wet loose avalanche, starting as a point release by rocks, in the Baker Backcountry. This is similar to what we expect to see on Thursday. Photo: Matt Crisler 

  • Wind Slabs

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

    On Wednesday, large and deep avalanche was triggered in a highly frequented area of the Baker backcountry. This avalanche was triggered after several people had already landed a jump in the same location . You can check out the well-written observation HERE. A large natural slab avalanche cycle occurred during the storm on April 3-5. Layers will slowly stabilize and become less reactive. However, the quantity of new snow and size of avalanches we saw once the storm cleared warrants continued caution. You are most likely to trigger a slab avalanche on steep, wind-loaded slopes. Cornice fall or smaller wet loose avalanches could also act as a trigger for a large wind slab avalanche. This could possibly occur in a location where a human is not able to provide the necessary weight to trigger an avalanche. 

    Search out locations of wind-drifted snow, identifying wind indicators such as wind lips, pillows, or textured surfaces. Strong winds during the last storm may have cross loaded terrain features so keep an eye out for unsual loading patterns. You're most likely to find drifts around features and rocky outcroppings, and in gullies. The drifts may be hard to identify, given the amount and distribution of snow. Avoid steep slopes where you find these features on Thursday. 

     

    (4/6/2022)

    A large avalanche which failed near the bottom of the storm snow, just above the summer road by Austin Pass in the Baker backcountry. The trigger was the 12th rider landing a jump in that location. We're glad no one was hurt and they provided a very helpful public observation to alert us to the event. 

    Photo: Public Obs

Avalanche Discussion

It didn't get quite as warm as we expected on Wednesday, and a breeze for most of the day kept surfaces cooler than we had anticipated. Early afternoon, a few rollerballs and small wet loose avalanches were reported in both the Baker backcountry and the Canyon Creek areas. There was less avalanche activity than we thought, but the change to significantly warmer temperatures forecasted for Thursday are alarming. Given the forecast, we suspect we'll see many more avalanches than we saw on Wednesday, warranting a rapid retreat from all avalanche terrain once avalanche activity begins.  Even if you're avoiding avalanche terrain and not getting into the steeps it's still a fine day spent out in the Cascades.

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