Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

Thu
Alta quota
2 · Moderato
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 6 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The avalanche danger should decrease on Thursday.  Where you find wind-stiffened snow assume you can trigger a shallow wind slab avalanche on similar terrain features.  Move off sunny slopes before mid-day if the snow surface starts to moisten and you see natural pinwheels and rollerballs. 

Problemi valanghivi

  • Wind Slabs

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

    You can still trigger shallow wind slab avalanches on wind-loaded slopes at higher elevations.  As you climb, feel for firmer or hollow sounding snow above the hard 12/21 crust.  The crust is 4-6" below the snow surface in non-wind affected areas and you may find drifts of around 1' deep or more on wind loaded slopes.  Steer around slopes below cornices and use caution near steep wind loaded terrain.

    Large to very large slab avalanches released during the storm cycle that ended Monday that featured heavy rain and snow.  Avalanche activity tied to these larger slides has subsided. Take a look at the media strip below to see some of the impressive avalanches that released earlier in the week. 

    This wind slab avalanche occurred sometime in the last couple days in the Mt Baker backcountry. Photo: Adam U

  • Loose Wet

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

    Wet loose avalanches are possible on south facing terrain Wednesday as afternoon freezing levels rise to 6000ft and higher.  Avalanches will mostly occur within the fresh snow that fell on Monday evening.  As snow surfaces moisten on sunny slopes make plans to shift around the compass to shady aspects. Alternatively if plans keep you on sunny aspects start early and get off steep slopes by the time they moisten midday. Rollerballs and pinwheels are the first indicators of surface layers losing strength, and start retreating when you see them coming down.

    Small wet loose avalanche on Tuesday in the Mt Baker backcountry. Photo: Pete Durr

Avalanche Discussion

Weakness in the snow above the 12/9 crust is a lingering concern.  If you dig a snow profile, look for lighter snow over the 12/9 crust with a heavier layer above that. This is buried up to 5ft deep, and slab avalanches ran on it over the weekend, although it has likely locked up since.  If travelling in mid and upper elevations where you may still find this layer consider limiting your exposure to large avalanche terrain.

The storm ended Monday night, with 10+ inches of water in the last week amounting to at least 4 feet of snow on top of the 12/9 crust. This much change requires time for the snowpack to settle and stabilize. We’ve seen a lot of avalanches in the last week. There are very few observations in the alpine due to the intense weather, limiting our knowledge of recent avalanches. If you do get out, let us know what the snow and avalanche conditions were like by submitting an observation.

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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