Bollettino valanghe

West Slopes North

Northwest Avalanche Center
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Pericolo valanghe

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

In sintesi

Avalanche danger will rise throughout the day as snowfall and wind speeds increase. You are more likely to trigger an avalanche on slopes with signs of recent wind loading, but assess all slopes with more than few inches of new snow. Head to sheltered terrain when it gets more stormy.

Problemi valanghivi

  • Storm Slabs

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

    Friday’s storm isn’t the strongest that has come through this season, but there is enough precipitation and wind to build fresh slabs. Rising snow levels and the possibility of surface hoar or weak facets under the new snow up the ante a bit more. You might find unstable slabs at low elevations to start the day, but they will likely get rained out or stuck in place as the day warms.

    Blowing and drifting snow will show you which slopes hold thicker, more sensitive slabs. Use a ski pole or simply dig down with your hand as you gain elevation and change aspects to look for differences in new snow depth and stiffness. More snow, denser snow, or a stronger layer over weaker one?  More likely you will trigger an avalanche on similar slopes that are steep enough to slide.

    Look for instability using test slopes, hand shears, and other simple tests. Whumphing or shooting cracks are signs you could trigger an avalanche if you head into steeper terrain. When in doubt just stick to simpler, sheltered, lower-angle terrain.

    You could find slabs like this in wind-exposed and also sheltered terrain on Friday.

    Photo: Andrew Kiefer

  • Loose Wet

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

    The potential to see rollerballs and wet avalanches should come from rising temperatures and wet snow and rain falling on dry snow. While most avalanches should be small, they can still do some harm in minimally snow-covered, low elevation terrain full of creek holes, rocks, etc. Don’t linger on or directly under steep slopes where you observe rollers, small wet avalanches, or find wet, unconsolidated snow.

    Slopes just below rocks and cliffs are where wet avalanches occur are more likely.

    Photo: Jason Speer

Avalanche Discussion

Be ready to find reactive slabs and greater danger at mid-elevations. Basic strong over weak layering and wind loading will drive avalanche danger in places where the old snow surface of surface hoar and/or facets was damaged. On the other hand, terrain that saw less wind or colder temperatures with Thursday’s mini-storm - places where weak snow survived as a uniform layer - could produce avalanches that propagate widely or take you by surprise. There isn't a surefire way to figure this out. The best policy would be to stick to lower angle, more planar terrain while the storm plays out.

Observers in the Baker BC noted a small amount of wind transport on Thursday, but just not enough to create a meaningful wind slab problem at mid-elevations. Warm temperatures also helped to keep surface snow stuck in place and likely quickened the bonding of shallow slabs that did form. Riding conditions were reported as still quite good despite the temperature increase. No observations came from upper-elevation terrain.

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