Bulletin d’avalanche

Northwest Coastal

Dec 4 – 5, 2011Avalanche Canada
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Archivé · expiré 15 years ago

Danger d’avalanche

Tue
Wed
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–5
    Big westerly winds combined with new snow will create fresh sensitive windslabs on lee aspects. These new windslabs will be burying old hard windslabs that may still be sensitive to human triggers.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–4
    Storm slabs will be an increasing problem throughout the day Monday. Carefully re-evaluate each run to account for changing conditions.

Confidence

Fair - Due to limited field observations

Weather Forecast

A radical above freezing layer is forecasted for Sunday night into Monday. Freezing levels as high as 2800m are possible. A cold front sweeps across the NW coast bringing as much as 30mm to the region Monday afternoon as ridgetop winds build to 80 - 95 km/h out of the W. Freezing levels lower Monday as the cold front moves inland.Cold post frontal air keeps the region dry & cool on Tuesday. Ridge of high pressure rebuilds Wednesday & Thursday with an outflow pattern. Another above freezing layer is forecasted for later in the week.

Avalanche Summary

Control work produced avalanches up to size 4.0 in the northern reaches of the forecast region. There are no reports of human triggered avalanches from the region.

Snowpack Summary

Very strong SW-NW winds may wreak havoc on the snowpack creating scoured areas and soft or hard wind slabs in exposed lee terrain and cross-loaded gullies or terrain features. Coastal areas are reporting a very deep and strong snowpack which is at or near record levels for this time of year. A buried surface hoar layer may be found down 100-150cm near Terrace, but there is no recent information on the presence and sensitivity of this layer.

Régions couvertes