Avalanche forecast

South Rockies

Apr 17 – 18, 2014Avalanche Canada
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Avalanche danger

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

This bulletin was created using very limited field data. If you are out in the mountains, please send your observations to [email protected]

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    If we get a little more snow than forecast we could see fresh wind slabs form in exposed lee terrain. Where the new snow is wet it may release as loose wet slides in sufficiently steep terrain.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–4
    Daytime heating makes cornices droop and become unstable. A large cornice release could also trigger a deep persistent weak layer and produce a very large avalanche.

Confidence

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

Weather Forecast

Friday: Cloudy with sunny breaks and scattered showers or flurries (~5-10 cm). The freezing level is around 1800 m. Winds are moderate gusting to strong from the west. Saturday: A mix of sun and cloud and warm! The freezing level rises to 2600 m and ridge winds are moderate to strong from the southwest. Sunday: Cloudy with sunny breaks and a chance of showers. The freezing level rises to 2200-2400 m and ridge winds are moderate from the west.

Avalanche Summary

On Thursday, the CAC field team observed a natural cornice failure which triggered a thin slab below near Window Mountain in the Crowsnest Pass. There were also several loose wet avalanches from steep terrain. The team also saw the remnants of a natural deep persistent slab that broke several large mature trees. This avalanche probably occurred in the past week or so, and most likely during a warming event.

Snowpack Summary

Above around 1800 m the mid and upper snowpack consists of layers of moist snow mixed in with several well bonded crusts, and around 10-15 cm of new snow on top. High north aspects may have around 30 cm of settled storm snow sitting on a crust, possibly more where wind loaded. Warm temperatures and periods of rain have made the snow surface wet below 1800 m, and at low elevations the entire snowpack is probably moist or wet. The deep facet/crust persistent weakness buried at the beginning of February (now down up to 80-100+ cm) should stay on your radar, especially on all alpine slopes during sunny periods. Any activity at this interface would be large and destructive. Also, give large sagging cornices a wide berth when traveling on or below corniced ridges.

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