Avalanche forecast

Purcells

Jan 19 – 20, 2016Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Variable conditions across the Purcells. Areas with deep recent storm snow accumulations may have higher avalanche danger.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–2
    Wind slabs may be lurking behind ridges and ribs. They may be extra sensitive where they overlie a buried sun crust.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    With each successive snowfall, a slab is slowly forming above a touchy buried weakness. This could be triggered by the weight of a person, even from a distance.

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Light amounts of snow are expected this week. Wed: 5-10 cm, mostly in the south; and cool with light winds. Thursday: flurries, freezing level rising to 1500 m, with moderate to strong SW winds. Friday: Flurries, freezing level around 1300 m, moderate SW winds. For more details check out https://avalanche.ca/weather.

Avalanche Summary

On Monday, several small slabs were triggered by skiers, including three that were remotely triggered. These were either on wind-loaded features at and above treeline, or in openings at low elevations, where buried surface hoar is largest and most reactive. These events suggest that there is a very touchy interface, but in general there is not enough load above it to create destructive avalanches. This situation could very quickly evolve and become dangerous, so watch for any areas with increased loading from wind or snow, and be alert if temperature changes cause the slab to become more cohesive.

Snowpack Summary

Conditions are variable across the Purcells. Isolated wind slabs are lurking behind ridges and ribs. 15-40 cm of recent storm snow overlies a mix of surface hoar, facets, and sun crusts that were buried in early January. In many parts of the Purcells, there is not yet a cohesive slab above this interface, apart from in wind-affected areas. In the far west of the region, there may be a deeper and more consolidated slab over the touchy early January interface. Operators are still keeping an eye on a more deeply buried layer of surface hoar from December, which is now considered dormant or unreactive. In general, the mid and lower snowpack is well settled and strong.

Regions covered