Bulletin d’avalanche

Kootenay Boundary

Dec 22 – 23, 2014Avalanche Canada
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Archivé · expiré 12 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

Monitor snow amounts carefully on Tuesday. Current conditions mean avalanches can be expected with relatively small additional amounts of new snow.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–5
    An avalanche on Sunday stepped down to deeply buried weak layers which formed in November. These destructive layers should remain on our radar as they could be triggered with large inputs such as a cornice fall or an avalanche in motion.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–4
    Expected new snow and wind will make storm slab avalanches very likely in this region once again by the end of Tuesday.

Confidence

Fair - Intensity of incoming weather systems is uncertain

Weather Forecast

A storm is expected start Tuesday afternoon, bringing up to 20 cm new snow from about 2 pm Tuesday to around midday Wednesday. Winds are expected to increase from around 30 km/h from the southwest on Tuesday, peaking at 50 km/h from the southwest on Wednesday afternoon before diminishing to 20 km/h from the northwest on Wednesday night. Freezing levels are expected to be around 1200 m for Tuesday and Wednesday. On Thursday, colder drier air moves in, lowering freezing levels to valley bottom and bringing light northwest winds.

Avalanche Summary

Widespread natural and remotely triggered storm slab avalanches to size 2.5 were reported from across this region on Sunday. They occurred on a variety of aspects and elevations between 1700 and 2200 m. The recently buried crust/surface hoar interface was the culprit in these avalanches. In one event near Rossland, a remotely triggered storm slab in motion stepped down to the November crust/facet interface near the ground on a planar slope at 2100m.

Snowpack Summary

Up to 50 cm of recent storm snow overlies a prominent surface hoar layer above a thick rain crust that extends as high as 2400 m. This crust/surface hoar interface was very reactive during the storm over the weekend, and still has the potential to produce further avalanches with additional load from new snow or wind, or in response to human triggers. High elevation north aspect slopes do not have the rain crust, but are still reported to have buried touchy surface hoar. On these slopes, deeper facets or buried surface hoar from earlier in the month may also be lurking. At the base of the snowpack, a crust/facet combo has become less likely to trigger, although a recent avalanche that occurred on this layer near Rossland indicates this layer should remain on our radar on steep, smooth terrain at treeline and in the alpine.

Régions couvertes