Avalanche forecast

South Columbia

Mar 29 – 30, 2016Avalanche Canada
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Avalanche danger

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

Special Public Avalanche Warning for this region. Forecast very warm temperatures, high freezing levels, and strong solar radiation will increase the avalanche danger.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–5
    Forecast high freezing levels, very warm daytime temperatures, and strong solar radiation are expected to result in natural cornice falls. Large cornice falls in motion may release deeply buried weak layers resulting in very large avalanches.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–6
    Intense spring sun and rising temperatures could reactivate buried persistent weaknesses in the upper snowpack.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    High daytime temperatures and strong solar radiation may result in natural loose wet avalanches at all elevations. Avoid sun exposed slopes if the snow is moist or wet.

Confidence

High

Weather Forecast

Clear skies and very warm daytime temperatures are forecast for the remainder of the week; freezing levels should reach at least 2500 metres. Winds are expected to be light from the west or northwest. There should be some radiative cooling overnight that may develop surface crusts, but the warm air mass may break these crusts down very early in the day.

Avalanche Summary

On Monday some recent storm slab avalanches were reported releasing from skier triggering up to size 1.0 on north aspects in the alpine. Some natural cornice activity was also reported up to size 2.5 from northeast and easterly aspects in the alpine. Forecast very warm temperatures and high freezing levels are expected to increase natural cornice activity, and may trigger the buried persistent weak layers.

Snowpack Summary

Approximately 5-10 cm of snow fell on Sunday, which will probably be sun-affected on solar aspects and wind-affected in exposed terrain from forecast northerly winds. Approximately 40-50 cm of settled storm snow sits on a melt-freeze crust buried on Mar. 22. The late February persistent weak layer is an aspect dependant mix of surface hoar, facets and/or a thick crust down around 60-110 cm below the snow surface. Commercial operators continue to see hard sudden planar results in snowpack tests, which suggests that wide fracture propagations are possible. Cornices continue to be described as large and fragile. Expect loose wet avalanches and natural cornice falls with strong solar radiation and significant warming this week.

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