Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

Avalanche danger will increase as more snow falls throughout the day. When new snow depths starts reaching around six inches, shift your travel to lower-angle slopes. Weak layers that formed at and near the surface in recent days could lead to more avalanche activity than expected, especially on shady upper-elevation slopes, where there's a small possibility that avalanches could break deeper than just the new layer. 

Problemi valanghivi

  • Storm Slabs

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

    Expect increasing danger as more snow falls throughout the day. At first, you might only be able to trigger avalanches in thicker pockets of wind slabs that build in the few inches of snow that has fallen. As we approach six inches, start shifting your travel away from steep slopes. 

    As snow nears four or more inches, use small test slopes to see if the new layer slides on snow beneath it. Search for bullseye clues like long, shooting crack or recent avalanches, as obvious signs to avoid steep terrain. When in doubt, stick to lower angle slopes. Small amounts of sluffing, or dry loose avalanches, could run in the new snow layer, too. 

    Observers reported surface hoar and faceted snow on and near the surface as of the 12th. Faceted growths mainly exist on shady aspects at upper elevations, whereas surface hoar may remain intact in sheltered mid-elevation areas. There isn't enough new snow or certainty with the distribution of these weak layers to say how much avalanche activity we'll see, but this isn't a good time to test slopes with the incoming new load. 

     

    Example photo: Soft, new slabs of snow could release on steep slopes as the snow starts growing deeper than just a few inches deep. 

Avalanche Discussion

Many lower elevation areas are no longer holding sufficient snow cover for avalanches to happen. If you find consistent snow cover near the top of the lower elevation band with a healthy coating of new snow, treat the area as if it were at mid-elevations. 

Clear skies over the last several days softened south-facing slopes, and there were some wet loose avalanches. A crust will exist at the old snow surface, and we don't expect weak layers in these areas, aside from a potentially good sliding surface. At upper elevations, the extent of wetting on south-facing slopes might be minimal, and a breakable crust with weak snow could exist on steep southerly aspects.

Observers noted significant losses in snow coverage at lower elevations. But if you make it high, coverage is reasonable, as you can read in THIS observation from Cascade Pass. If you're planning on tackling any steep, snow-covered terrain where crusts may exist, consider carrying a form of crampons or ice axe to reduce your sliding risk. Another significant factor to be aware of is that snow conditions vary widely by aspect and elevation. Expect variable, bumpy surfaces beneath any soft new snow. 

We're expecting around six inches of snow during the day on Friday, but that number will probably vary greatly depending on where you are in the zone. On shady slopes in the Baker backcountry, 4-6 inches of soft, dry snow was reported above the 2/7 crust, which was similar to further east in the zone. Shady upper elevation aspects in other areas could have a foot or more of snow over crusts.  

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