Bulletin d’avalanche

South Rockies

Jan 15 – 16, 2017Avalanche Canada
Voir sur la carte
Archivé · expiré 10 years ago

Danger d’avalanche

Mon
Tue
Alpin
2 · Modéré
Limite forestière
2 · Modéré
Sous la limite
1 · Faible
Ouvrir la carte complète

Points saillants

One more day of cool weather until rising temperatures elevate the danger.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible - Likely
    Taille
    1–2
    Lingering wind slabs can be found on a variety of aspects and may become sensitive to human triggering with warming temperatures.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Unlikely - Possible
    Taille
    2–3
    Stiffer snow overlies weak sugary snow in shallow snowpack areas, creating the potential to trigger large destructive avalanches.

Confidence

Moderate - Freezing levels are uncertain on Tuesday

Weather Forecast

MONDAY: Cloudy, moderate winds increasing to strong throughout the day, alpine temperatures around -6 and rising overnight.TUESDAY: Scattered flurries with up to 5 cm of new snow, extreme southwest winds, freezing levels around 1600 m and possibly higher on the eastern slopes.WEDNESDAY: Scattered flurries with up to 5 cm of new snow, strong southwest winds, freezing levels around 1800 m and possibly higher on the eastern slopes.

Avalanche Summary

No new avalanche reports from the weekend. An MIN report from Waterton Park on Friday shows a large size 3 deep persistent slab avalanche triggered by a smaller wind slab on a feature with highly variable snow depths. Although an isolated event, this avalanche highlights the possible consequence of our tricky persistent slab problem, especially with the incoming change of weather.

Snowpack Summary

Up to 20 cm of recent snow has buried a variety of old snow surfaces. These consist of heavily wind scoured areas and old wind slabs, surface hoar in sheltered areas, and widespread faceted (sugary) old snow. Recent moderate winds from a variety of directions have redistributed some of this new snow on leeward slopes, forming reactive wind slabs.The mid pack appears to be quite variable throughout the region and the structure is dependent on snow depth. In deeper snowpack areas, the snowpack appears to be well settled and right side up with isolated concerns for the mid-December weak layer found 50 to 80 cm deep. In shallow snowpack areas and lower elevations, the snowpack is heavily faceted and there are concerns for the mid-December weak facet layer as well as weak basal facets. If a persistent slab is triggered from thinner snowpack areas it may release on the basal facets resulting in a full depth avalanche. At this point it seems like a low probability, high consequence scenario. However; once the snowpack starts to see a big change, like warming, the likelihood of triggering may increase.

Régions couvertes