Bollettino valanghe

Purcells

Dec 31, 2016 – Jan 1, 2017Avalanche Canada
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Archiviato · scaduto 10 years ago

Pericolo valanghe

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

In sintesi

Fresh wind slabs are forming at higher elevations, and have the potential to step down to a lingering persistent weak layer. Watch for signs of instability and choose conservative routes. 

Problemi valanghivi

  • Wind Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Likely
    Dimensione
    1–2
    Wind slabs can be expected on all aspects as winds will shift from the southwest to the northeast.
  • Persistent Slabs

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    2–3
    40-80 cm of snow sits above a weak layer of facets from mid-December and continues to be reactive in parts of the region that have thinner snowpacks.

Weather Forecast

SUNDAY: Morning flurries easing off in the afternoon, moderate northeast winds, alpine temperatures around -18.MONDAY: Mix of sun and cloud, light east winds, alpine temperatures around -22.TUESDAY: Sunny with cloudy periods, light east winds, alpine temperatures around -18.

Confidence

Moderate - Wind speed and direction is uncertain

Avalanche Summary

On Friday, there were numerous reports of size 2 avalanches including natural and skier-triggered loose dry avalanches and explosive-triggered wind slabs. There were also isolated reports of size 2 storm slabs on Saturday, including one that stepped down to glacial ice on a steep south-facing slope. Expect touchy wind slabs to develop as moderate winds redistribute loose snow in exposed terrain.Also, a notable MIN report from Friday shows what seems to be a size 2 persistent slab that was triggered by a ski cut in a cutblock west of Kimberly (see MIN report from Mallandaine Pass). This is a reminder that although avalanche activity on persistent facet layers has been intermittent, the problem will likely linger for some time in shallow snowpack areas.

Snowpack Summary

The region received a total of 40-60 cm of low density snow over the past week. Recent winds have come from a variety of directions and have loaded leeward and cross loaded features in exposed terrain. An interface that formed during the early December cold snap can be found buried 40-80 cm deep. The interface may consist of stiff wind-affected snow, faceted (sugary) crystals, or surface hoar crystals. The overlying slab appears to have a poor bond to the interface in some areas, such as wind-affected terrain in the Dogtooth range and shallow snowpack areas like the southern Purcells. The thick mid-November crust and facet layer is now buried 70-150 cm deep and appears to be dormant.

Regioni coperte