Bulletin d’avalanche

Jasper

Mar 11 – 12, 2017Parks Canada
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Archivé · expiré 10 years ago

Danger d’avalanche

Sat
Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
1 · Faible
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Points saillants

Winds are whipping up 45cm of low density snow into slabs. Assess each slope carefully.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–3
    SE winds are creating slab on lee aspects and firming it up on windward aspects. March 3rds 45cm of low density snow is available for transport. It may be overtop a decomposed SH layer on CR 30cm down on South TL aspects. 

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–3
    Persistent mid-pack slab condition has been developing all season. Various wind and facet layers exist. Spatial variability exists with thick and thin snowpack areas. 

  • Deep Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    2–3
    Natural activity has subsided but don't let your guard down. It remains a major concern with a extremely weak base of depth hoar. Trigger spots would be shallow zones or a step down effect if upper layers are initiated.

Weather Forecast

Saturday into Sunday a.m. will be clouds, 5-10cm of snow, 25km/hr South to Southwest sinds, and -4 to -6 degrees Celsius. Winds speed increases slightly Sunday and Monday out of the W-SW with clouds and flurries. Temperatures will remain the same.

Snowpack Summary

SE Winds are creating windslabs 30-60cm thick. It rests on a persistent slab that has a cornucopia of wind and facet layers throughout the midpack. The lower snowpack is weak with depth hoar and a November rain crust. S aspect at Parker's there is a Surface hoar layer on a sun crust down 30cm testing unstable sudden planar fracture characteristic.

Avalanche Summary

Friday's field patrol into Portal creek from Marmot basin had no whumphing or shooting cracks. Thursday a cornice triggered a size 2.5 on Parkers Slabs. Churchill slide path on Thursday observed no whumphing or shooting cracks but the team stayed very conservative near the trees. Skiers on March 7 in Bald hills triggered a size 2 from a km away.

Confidence

Wind effect is extremely variable

Régions couvertes