Bulletin d’avalanche

Jasper

Nov 21 – 22, 2021
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Archivé · expiré 5 years ago

Danger d’avalanche

Mon
Tue
Alpin
3 · Marqué
Limite forestière
2 · Modéré
Sous la limite
1 · Faible

Points saillants

Strong west to south-west winds expected to add load to the recently formed wind slabs and persistent slab as there is still a lot of snow available for transport.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–2.5

    Watch for wind loading at ridge tops and in the alpine with recent West and SW winds. Strong winds are expected to persist into Monday with a lot of snow still available for transport.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1.5–3

    60-80cm of storm snow from Nov 13-15th has settled into a persistent slab condition. Field tests are showing sudden collapse on a crust down 50-80cm over weak facets. The snowpack is still at its infancy and the prudent thing to do is be cautious.

Confidence

Weather Forecast

Sunday: Cloudy with isolated flurries. Precip: Trace. Alp temperature: High -7 C. Ridge wind southwest: 20-35 km/h.Monday: Snow: 9 cm. Alpine temperature: Low -10 C, High -5 C. Wind southwest: 20-40 km/h. FL: 1400 metres.Tuesday: Cloudy with scattered flurries: 4 cm. Alp temp: Low -13 C, High -7 C. Wind west: 15 km/h gusting to 45 km/h.

Snowpack Summary

Surface hoar of up to 4mm observed on all aspects up into alpine prior to the current strong W- SW winds. The storm snow has now formed persistent slab particularly in wind loaded features. A 2cm thick crust 80cm down is found up to 2500m or higher. Weak facets below the crust result in sudden collapse test results.

Avalanche Summary

Friday's team observed two size 2 persistent slab avalanches on windloaded features in the alpine and treeline. On Wednesday numerous avalanches up to size 3.5, generally from steep alpine features, were noted. They occurred during or at the end of the Nov 13-15th storm. One 800m wide avalanche was caused by explosives at tree-line on Tuesday.

Régions couvertes