Bulletin d’avalanche

Kootenay Boundary

Mar 12 – 13, 2012Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Wed
Thu
Alpin
4 · Fort
Limite forestière
4 · Fort
Sous la limite
4 · Fort
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Points saillants

Don't get message fatigue. Heed the high danger warnings. Read the forecaster blog for more details.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–5
    Wind slabs are forming at all elevations with extreme winds and are expected to become very touchy in the lee of exposed terrain features.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    3–8
    The deeply buried surface hoar may be forced into action by heavy loading from wind and snow Mon & Tue. The tricky nature of this layer means that terrain at all elevations has the potential to produce large destructive avalanches.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–4
    Heavy snowfall with the forecast weather will set up unstable conditions in the upper snowpack layers.

Confidence

Good

Weather Forecast

Heavy snowfall is expected overnight (Monday night) with 30 + cm expected in some areas by morning. Strong to extreme SW winds, freezing levels around 1100 m. On Tuesday, Heavy snowfall is expected to continue into Tuesday and become lighter in the afternoon. Winds should start to diminish. Freezing levels should fall slightly. On Wednesday, there may be a lull between storms, although snowfall is expected to start up again later on in the day. On Thursday, another frontal system arrives in this region, bringing further heavy snowfall, strong SW winds and freezing levels in the 1200 m range.

Avalanche Summary

On Sunday, avalanches could be easily triggered in the new storm snow up to size 1.5. Sluggish sluffing in the storm snow was observed in steep terrain on Saturday.From earlier in the week:Several natural avalanches were reported Thursday to size 3. One noteworthy event was a size 2 avalanche that was triggered by cornice fall. The size 2 ran 50m before triggering a size 3 avalanche in lower angle terrain. The crown was reported to be 200cm in depth, failing on the Feb. 08 SH. One reported avalanche was remote triggered from 20m away on a 35 degree slope.

Snowpack Summary

Approximately 25 cm new snow fell on top of previous storm amounts from Friday night and Saturday night. This has added to the snow amounts overlying a 2 - 6mm surface hoar on north aspects and a 2cm sun crust on solar aspects. Moist snow was found Friday to 1800m, I suspect there was little change Saturday. The leap year SH is now down around 40 - 50 cm and is failing as a resistant planar shear in snowpack tests. The early February surface hoar is down 80 - 140cm, snowpack tests show moderate to hard forces generating sudden planar shears on this layer.

Régions couvertes