Avalanche forecast

South Rockies

Feb 20, 2019Avalanche Canada
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Archived · expired 8 years ago

Avalanche danger

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

Rider triggered avalanches on persistent weak layers remains possible at lower elevations. Terrain like cutblocks, steep forest openings and gullies are still suspect. At upper elevations wind slabs are the primary avalanche concern.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    Use added caution in lee terrain features near ridges, as winds have formed deeper deposits. The wind was first from the west and more recently from the northeast, so all lee features are suspect.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1–2.5
    A weak layer of surface hoar is buried around 50 to 80 cm, which is best preserved in shaded and sheltered areas between 1600 m and 1900 m.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

TUESDAY NIGHT: Cloudy, trace accumulations, light northwest wind, alpine temperature -13 C.WEDNESDAY: Cloudy with light snowfall, accumulation 1-5 cm, light to moderate northeast wind, alpine temperature -11 C.THURSDAY: Cloudy with sunny breaks, light west winds, alpine temperature -10 C.FRIDAY: Cloudy, light snow, light west winds, alpine temperature -10.

Avalanche Summary

There was evidence of many small to large (size 1 to 2) natural wind slab avalanches in the region over the last three days. More recently ski cutting has produced small avalanches over convex features at various elevations. Sled cuts were still producing slab avalanches at lower elevations on cut banks and cutblock type terrain on the last South Rockies Field Team trip to this region. There was also evidence of 40 cm slabs scrubbing to ground in very shallow snowpack areas.

Snowpack Summary

Around 20 to 30 cm of snow fell within the past three days, with the highest amounts in the south of the region. The snow likely has slab properties where it has been wind affected at higher elevations and open areas. It could be more loose in sheltered areas.The mid-January layer weak layer is buried around 50 to 80 cm. The weak layer is surface hoar on shaded and sheltered slopes and is most prominent between 1600 m and 1900 m but has been found up to 2200 m. In some areas the weak layer is made up of sugary faceted crystals over old wind slab or a crust. Snowpack test results suggest that this layer may still be triggered by humans.The middle of the snowpack is generally consolidated. The bottom half of the snowpack is unconsolidated and composed of weak and sugary faceted grains. There is potential for shallower avalanches to step down to these deeper weak layers.

Regions covered