Bollettino valanghe

East Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

New snow and impressive winds are creating dangerous avalanche conditions at upper elevations. It could be easy to trigger fresh wind slabs that may start as shallow slides but in some areas may step down to become deeper, larger avalanches. Play it safe by sticking to lower angled slopes as you gain elevation, especially if you find signs of instability like shooting cracks or hear whumphing. 

Problemi valanghivi

  • Wind Slabs

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

    Strong winds have been drifting recent snow into more cohesive slabs on exposed mid and upper-elevation slopes. These could be surprisingly reactive, as they may form over weaker snow on a crust. Slabs could be 6"-18" deep in favored locations, and in some areas may have the potential to step down to deeper crust layers. Use caution as you gain elevation, and stick to lower angled slopes if you venture to the alpine. Look for signs of instability like shooting cracks, whumphing collapses, and observe for active wind loading. Likely spots to initiate wind slabs are on open slopes exposed to the wind, near large rock outcroppings, at the top of convex rollers, and steep, sparsely treed slopes. 

    Textured surfaces, deeper drifts, and cornice formations can also help you identify likely wind slab locations. However, in areas where you find more than 12" of new snow, expect more widespread slab development. Small loose dry sluffs could also be possible in some areas. If you find the snow is prone to sluffing, or cracking, than its recommended to steer around steep, consequential slopes. 

    Example of textured, wind loaded area.

    Photo: Hans Brubaker

Avalanche Discussion

Winds have been steadily in the teens, though recently bumped to the 20's and gusting to mid 30's at Washington Pass. These are impressive wind speeds for this site! We're expecting the bulk of the new snow to fall overnight Friday into early Saturday morning, but snowfall should continue to trickle in during the day. 

An observer on Thursday found 3" of new snow near Blue Lake. He reported light drifting snow during the day, while winds were just beginning to increase. Earlier in the week, observers in the Kangaroo ridge area reported firm, wind affected surfaces at very high elevations with minor cracking. Prior to Friday, observers found nice powder riding conditions and a barely noticeable crust below recent snow accumulations. 

The top foot or two of the snowpack holds multiple crusts at mid elevations, and one more stout crust exists from early December to about 8,000ft. These crust layers have been found with and without weaker snow around them. As more snow accumulates, these will be worth digging down and testing. Region wide, these crusts are expected to become main players for avalanches through the weekend and into the week. For an idea of what you might find in the southern portion of this zone, like mid-Twisp River drainage, check out these observations from the Holden area.

You can help out by contributing to the forecast. Submit an observation, and let us know what you see! 

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