Avalanche forecast

South Rockies

Mar 15 – 16, 2014Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
4 · High
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Incoming weather combined with a complex snowpack means this is no time to be pushing into steep terrain. Conservative slope selection is critical to safe mountain travel.

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–4
    Steady snowfall and wind will add to a developing storm slab problem. Expect touchy conditions, especially in wind exposed terrain or in places where the new slab overlies buried crusts.

  • Wet Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–4
    Forecast precipitation is expected to fall as rain at lower elevations with the potential to trigger deep and pushy wet slab avalanches. Be cautious of slopes that did not avalanche during the last big cycle.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–6
    In some areas the deeply buried weak layers that formed in early February are still showing significant reactivity in snowpack tests. Avalanches at this interface would be large and destructive and are possible at all elevation bands.

Confidence

Poor - Intensity of incoming weather systems is uncertain on Sunday

Weather Forecast

Overview: A pacific frontal system will push inland on Saturday bringing moisture to the interior until early Monday morning. Expect a ridge of high pressure to develop for Monday and Tuesday. Due to significant weather model disagreement for Sunday, I have limited confidence in forecast snowfall amounts and freezing levels.Sunday: Moderate snowfall with the greatest amounts falling in the south / Moderate westerly winds with extreme gusts / Freezing level between 1700m and 2000mMonday: A mix of sun and cloud / Moderate westerly winds becoming northwesterly with strong gusts / Freezing level at 1500mTuesday: Mainly sunny skies / Light northwest winds / Freezing level at about 1200m

Avalanche Summary

A recent natural cornice triggered Size 2.5 avalanche was observed Smith Basin area north of Elkford. I expect a new round of storm slab activity with forecast weather. Rain at lower elevations may activate wet slab avalanches.

Snowpack Summary

Light to moderate amounts of new snow overlie crusts on previously sun-exposed slopes. The bond between the new snow and the freshly buried crusts is expected to be quite weak. With more snow and wind on the way, the size and reactivity of the developing storm slab will increase. Forecast rain at lower elevations may also reactivate potent wet slabs.The deep facet/crust persistent weakness buried at the beginning of February, now down up to 150cm, is still producing sudden results in snowpack tests. I would be very leery of any slopes that have not already avalanches as any avalanches at this interface would be large and destructive. Triggering will become more likely if forecast precipitation falls as rain.Cornices have also become large and potentially unstable.

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