Bulletin d’avalanche

Kananaskis

Dec 20 – 21, 2016Alberta Parks
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Archivé · expiré 10 years ago

Danger d’avalanche

Wed
Thu
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
1 · Faible
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Points saillants

Snow and wind have joined forces to give us a touchier snowpack that what we are used to. Conservative terrain is recommended for the next while.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–3
    In the alpine, these slabs are now buried beneath the storm slabs. They will be harder to detect with the new snow texture. Use small terrain to find them and assess them often. Climbers!! Watch for pockets of hard slab on and around routes!

  • Loose Dry

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2
    Still a concern given our mainly facetted snow pack. Gully features should be avoided. Ice climbers should be very aware of this concern.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    2–3
    These tend to be in the higher, wind prone areas. Upper Treeline & alpine are the likely areas to find these new slabs. Watch overhead exposure and treat any wind loaded slope with respect.

Confidence

High -

Weather Forecast

Mainly cloudy tomorrow with little forecasted snow. Don't be surprised if we do get small amounts of fresh snow near the divide. Temperatures will continue to hover around -11.  Winds are the real story, expect steady alpine winds of 70 km/hr with significantly higher gusts .

Avalanche Summary

2 separate incidents to talk about today:1) Forecasters remotely triggers a Sz 2 in alpine terrain. As the team walked on the top of a ridge, they triggered a small cornice chunk(10m away) that went on to release the storm slab below. The slab itself was up to 40cm thick and entrained a large amount of snow as it traveled. East aspect, 2400m, a short steep slope with a large fetch.2) A party of 3 scramblers triggered a Sz 2 slab in alpine terrain and went for a ride. Details are largely unknown, but it occurred in typical front range mixed scree/snow terrain near Wind Tower.

Snowpack Summary

Strong alpine and treeline winds have transported a huge amount of snow. Any new snow that fell has been blown into storm slabs. Even the older facetted snow has been blown around to create fresh windslabs. Areas near the divide (Burstall Pass) saw up to 20cm of new snow in the last 24-48 hours. When that fresh snow is combined with wind, slabs up to 60cm thick are common. Open areas at treeline and alpine have a widespread windslab problem and alpine areas have an additional storm slab problem in immediate lees(easterly aspects). It feels as though we are on the verge of a small natural cycle. These slabs appear to be running on the older windslabs, but quickly involving the midpack facets. The mid pack is weak enough that entrainment after the initial failure is a real concern.

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