Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

Wet avalanches in sun exposed terrain are possible with clear skies and warming. Move off and away from steep slopes when you start to witness rollerballs or small wet avalanches.  Limited observations above treeline will require you to assess conditions as you ascend.

Problemi valanghivi

  • Loose Wet

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

    Clouds and cooler temperatures limited wet avalanche activity on Friday, especially near treeline.  A few very large loose wet avalanches that in turn triggered slab avalanches were observed late in the day in south facing, alpine terrain. Though it’s likely we will have a warmer day Saturday, there is uncertainty as to the size and extent of avalanche activity that the sun and rising temperatures will foster. It is certain that deep dry snow above the treeline will be more susceptible to warming than rain saturated snow at lower elevations. 

    You will probably see signs of instability like rollerballs, pinwheels, or small avalanches on slopes that get direct sun. When these are observed consider limiting your exposure to similar terrain. If you start seeing loose wet avalanches occurring regularly and growing larger then the avalanche danger has ratcheted up to Considerable. In this event avoid being on or under all steep sun-exposed terrain. Loose wet avalanches are unlikely if the snow surface is frozen or partially melted.  

    (3/4/2022)

    Natural loose wet avalanches on a south aspect of Mt. Herman at 5000-5400'. They occurred on the afternoon of the 3rd.

    Photo: Lee Lazzara

Avalanche Discussion

In addition to wet avalanches, isolated but reactive storm and wind slabs might be found above treeline. Wind transport was noted on the upper reaches of Mt. Baker Friday. With limited observations, it is up to you to assess stability as you gain elevation. Anticipate higher danger in wind loaded or sun warmed terrain and mitigate uncertainty by avoiding steep and unsupported terrain features.

A loose wet avalanche cycle to D2 occurred on southerly aspects Thursday afternoon. Observed avalanches appeared to involve only the top layer of new snow and did not entrain deeper wet snow layers. Good visibility allowed documentation of widespread avalanche activity from earlier in the week. Crowns showing wide propagation and step-downs in bed surfaces show that avalanche activity was not confined to new snow layers but also broke into deeper layers around the February 14th crust. 

Surface conditions vary widely from slope to slope with a mix of sun crust, sun-softened snow, extensive avalanche debris, and even settled dry snow masquerading as powder on north aspects near and above treeline. 

Regioni coperte