Bulletin d’avalanche

Sea To Sky

Nov 25 – 26, 2017Avalanche Canada
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Archivé · expiré 9 years ago

Danger d’avalanche

Mon
Tue
Alpin
4 · Fort
Limite forestière
3 · Marqué
Sous la limite
2 · Modéré
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Points saillants

A natural avalanche cycle is expected on Sunday as rain batters the snowpack. Conditions will be especially dangerous at higher elevations where rain falls on dry snow.

Problèmes avalancheux

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Very Likely
    Taille
    1–3
    Rain will be a powerful trigger for storm slab avalanches on Sunday as it rapidly loads and warms the upper snowpack at higher elevations. Touchy new storm slabs may also form at higher elevations as rain transitions to snow over the day.

  • Loose Wet

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely - Very Likely
    Taille
    1–3
    Warm, wet weather will destabilize surface snow and encourage loose wet avalanching on Sunday, especially in steep terrain. Even a small release can develop into a very dangerous problem as it gathers mass traveling downslope.

Snowpack Summary

Approximately 20-30 cm of new snow overlies the November 23 crust. This 5-10 cm thick crust can be found on all aspects above 1400 m and overlies a generally rain-saturated snowpack. Below treeline the snowpack consists of wet snow from top to bottom. In high alpine and glaciated terrain a layer of weak sugary crystals that was buried on November 9th exists above a crust near the base of the snowpack. This interface is now buried 150-240 cm deep.

Confidence

High -

Weather Forecast

Sunday: Heavy rain (30-60mm) developing into wet flurries bringing up to 20 cm of new snow to alpine elevations. Strong to extreme southwest winds. Freezing level dropping from about 2200 to 1500 metres over the day. Alpine temperatures dropping from around +2 to -2 over the day.Monday: Mainly cloudy with scattered flurries bringing approximately 5 cm of new snow. Light southwest winds. Freezing level to about 1100 metres with alpine temperatures of -5.Tuesday: Periods of snow bringing 15-20 cm of new snow. Strong southwest winds. Freezing level to 1500 metres with alpine temperatures of -3.

Avalanche Summary

Wednesday's rain to mountain tops produced numerous, small to very large natural, loose, wet avalanches as rain drenched all elevations. In some areas these avalanches were associated with debris flows and several washouts along forestry roads and trails have been reported. Avalanche activity has since subsided with a return to cooler temperatures and lower freezing levels but will increase again as the new snow and wind build storm slabs at alpine and treeline elevations.

Régions couvertes