Avalanche forecast

South Rockies

Apr 10 – 11, 2014Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–4
    Daytime heating makes cornices droop and become unstable. Also, if anything is able to trigger the deep persistent weak layers, a cornice fall is what might do it.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Warm temperatures and/or intense sunshine turn the snow surface to mush increasing the likelihood of a loose wet avalanche.

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Friday: Dry during the day with a mix of sun and cloud. Showers in the evening. Freezing level 2100 m. Ridgetop winds 20-30 km/h from the west. Friday night: 5 cm or so new snow expected. Winds light. Saturday: Showers possible. Some sunshine also likely. Freezing level around 1500 m. Calm winds. Sunday: Dry with a mix of sun and cloud. Freezing level 1900 m. Calm winds.

Avalanche Summary

A size 3.0 avalanche in the Harvey pass area on April 4th was reported to have started from a cornice fall and stepped down to the February deep persistent weak layer. Loose wet avalanches have been reported in the surface since then during periods of warming.

Snowpack Summary

Very warm temperatures over the past few days and high freezing levels with no crust recovery have resulted in moist or wet snow at all elevations.In the Smith Basin area there is 140 cm below treeline and the top 40 cm was found to be moist and well consolidated. The March crust below was decomposing at this location. The February deep persistent weak layer was down 80 cm and well preserved. Higher up at about 2300 metres the height of snow was a little over two metres. The March crust was not intact at this location and did not result in any shears in snow profile tests. The February deep persistent weak layer (DPWL) was down 100 cm and was a well defined layer of softer facetted snow below the hard (pencil) snow of the well settled mid-pack. Hard sudden collapse shears were recorded at the interface of the February DPWL. In the Elk Valley South the height of snow at 1900 metres was 430 cm. The snow was dry and loose above 1700-1800 metres and moist below where loose wet slides had released on solar aspects. There was a 2-3 cm supportive crust on Southerly aspects above 1900 metres, and no crust on shaded North aspects.

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