Bollettino valanghe

Kootenay Boundary

Feb 10, 2019Avalanche Canada
Vedi sulla mappa
Archiviato · scaduto 8 years ago

Pericolo valanghe

Mon
Tue
Alta quota
3 · Marcato
Limite del bosco
3 · Marcato
Sotto il limite
2 · Moderato
Apri la mappa completa

In sintesi

Strong winds have redistributed loose snow forming touchy wind slabs. The deepest and most sensitive deposits will be in wind-loaded features: around ridges and rolls, under cornices, and in cross-loaded terrain.

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible - Likely
    Dimensione
    1–2
    Touchy wind slabs have been reported on south and east aspects. Forecasted winds are variable in both speed and direction and will continue to transport loose snow and develop slabs. The most reactive slabs will be in wind- and cross-loaded terrain.

  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2
    There is a layer a layer of weak feathery surface hoar 20-40 cm below the surface and another 40-80 cm down. The former most reactive, especially where it is sitting on a crust.

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

SATURDAY NIGHT: Cloudy with starry breaks. Alpine temperatures near -20C. Ridgetop winds moderate from the east. SUNDAY: Mix of sun and cloud, isolated flurries in evening, trace accumulation. Alpine temperatures near -14C. Ridgetop winds light from the south.MONDAY: Mix of sun and cloud, isolated flurries in evening, trace accumulation. Alpine temperatures near -15C. Ridgetop winds light from the southeast.TUESDAY: Cloudy with scattered flurries, 5-10 cm accumulation. Alpine temperatures near -15C. Ridgetop winds moderate from the southeast.

Avalanche Summary

Several large (size 1-2.5) natural wind slab avalanches occurred on all aspects at treeline and above sometime late Friday evening. Widespread wind effect was noted through Friday with scouring and wind-loading on a variety of aspects. Small wind slabs (size 1-1.5) were reactive to skier traffic. On Wednesday, a skier remotely triggered a size 1.5 slab avalanche approximately 200 m away from them off the same ridgeline that they were traveling on, the suspect failure plain being the February 1st surface hoar interface that was buried last weekend. Additionally, slab avalanches failing on this layer were also easily triggered up to size 1.5 on north and and east-southeast aspects around 2000 m early in the week. With the cold temperatures and a bit of new snow, loose dry sluffing from steeper terrain features can be expected.

Snowpack Summary

Winds are redistributing 10-30 cm of low density snow, scouring exposed aspects and developing pockets of touchy wind slabs in lee terrain. This wind-affected snow covers on variety of snow surfaces, including buried wind crust on westerly aspects, sun crust on southerly aspects to mountain top and weak feathery surface hoar crystals in sheltered areas at treeline and below. The snowpack now hosts two buried surface hoar layers. The one that was buried on February 1st (down 20-40 cm) seems to be more predominant and reactive to human triggers than the one buried deeper down (40-80 cm). This deeper layer of surface hoar may be most reactive below treeline on shady aspects but doesn't seem to be a widespread problem in the region. The mid-pack is generally well-settled and strong.

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