Bulletin d’avalanche

Purcells

Mar 10 – 11, 2014Avalanche Canada
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Archivé · expiré 13 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré

Points saillants

Warming temperatures and Solar radiation will play a leading role in the avalanche hazard in the coming days. Pay special attention to large ripe cornices !

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–4
    Recent storm snow is settling into a dense slab that overlies a variety of weak layers. Warm temperatures will set the stage for natural and rider triggered avalanches, use caution in recently wind loaded terrain. Cornice hazard is a real  concern.
  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–5
    Additional loading and rising temperatures make the possibility of triggering deep layers more likely. A cornice failure could produce a large enough load to trigger  deeply buried weak layers.

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Synopsis: The Pineapple express that plowed its way across the province in the last few days has moved south and east leaving us with a high pressure and some clearer weather for the next few days.Tonight: Clear with cloudy periods, freezing level at valley bottom. ridge top winds light to moderate from the north west.Tuesday: Mix of sun and clouds, no precipitation in the forecast, light to moderate winds at ridge tops, freezing level climbs to 1500.Wednesday: Sunny with cloudy periods, no precipitation in the forecast, freezing level rising to 1800m. winds from the south west, light to moderate.Thursday:  Sunny with cloudy periods, possibility of flurries, freezing level rising to 1500m. Light ridge top winds from the west.

Avalanche Summary

The numbers avalanches running naturally has diminished, with the bulk being in the south of the forecast area.  Cornice failures are beginning to show up on the reports, and explosive testing is producing large avalanches with widespread propagations.  Neighboring forecast regions have reported large avalanches initiating in the new storm snow, then stepping down to deeper layers, some running full path to the ground. The South Columbia's reported a size 4.5 on a south-west aspect than ran more that 1500 vertical metres.

Snowpack Summary

Recent snowfall amounts have been highly variable throughout the region. In some deeper snowpack areas 80 to 100cm of storm snow overlies a weak surface hoar layer that has been preserved in sheltered areas. A buried sun crust exists on solar aspects and and there are growing wind slabs in exposed terrain. On lee slopes these accumulations have been pushed into much deeper deposits by moderate to strong southwest winds. Warming has added cohesion to the slab and wider propagations have been reported. With rising temps and solar radiation, moist snow surfaces have been reported into the alpine.Wet avalanches on solar aspects have also been reported. There is ongoing concern for a mix of weak surfaces which were buried on February 10th. This persistent interface lies between 60 and 160cm below the surface, and includes surface hoar, well developed facets and a mix of hard surfaces which remain widespread at all aspects and elevations. In manyparts of the forecast area, large destructive avalanches are still a very real concern with ongoing reports of natural avalanches running full path. Weak basal facets exist in many areas, but without a large load, triggering now is unlikely.

Régions couvertes