Bulletin d’avalanche

Northwest Coastal

Feb 13 – 14, 2015Avalanche Canada
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Archivé · expiré 12 years ago

Danger d’avalanche

Sun
Mon
Alpin
3 · Marqué
Limite forestière
3 · Marqué
Sous la limite
3 · Marqué
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Points saillants

While avalanche danger will decrease in the wake of the storm I would make conservative terrain choices for a few more days until the snowpack has adjusted the recent load and warming.

Problèmes avalancheux

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    3–7
    I'm unsure as to how the recent storm affected the deeper problem layers in the snowpack. I would manage this by assuming that every slope above treeline still has the potential to produce a very large and destructive avalanche.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    2–5
    Above 1000m heavy snowfall has loaded a thin layer of surface hoar. I expect touchy avalanche conditions to linger for a couple of days after the storm subsides.

  • Wet Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    1–2
    Rain has saturated the snowpack at lower elevations. Loose wet avalanches are possible in steep open terrain and gullies.

Confidence

Poor - Due to the quality of field observations

Weather Forecast

A ridge will build over the weekend signaling an end to the deluge. Rain will continue overnight Friday with coastal regions receiving up to 10mm of rain and snow although this is expected to taper off rapidly further inland. The freezing level is forecast to drop to 1000m on Saturday with moderate westerly winds. Isolated showers may persist into Sunday although a clearing trend is expected as the winds become northwesterly, bringing scattered clouds and a freezing level of 750m. The region should be mainly dry by Monday when broken skies, light south west winds, and a freezing level of 1500m are expected.

Avalanche Summary

Warm temperatures, wind, snow and rain drove a natural avalanche cycle that started on Wednesday.  Since then we have received reports of  numerous natural and explosive controlled slab avalanches up to size 3 on all aspects above 1000m with widespread loose wet avalanche activity bellow . I am unsure if all of these avalanche were contained to the storm snow or if some may have released on one of the deeper week layers.

Snowpack Summary

Between 20 to 70 mm of precipitation in the form of new snow and/or rain had fallen through the storm as of Friday evening. In many places this sits on a thin layer of surface hoar that formed in the brief lull between systems on Febuary 10th. The freezing level rose to 1500m in the southwest corner of the region on Friday with cooler temperatures recorded further inland and to the north. Predominantly strong southwest winds have loaded lee features in the alpine and at treeline. Before this storm the late-January crust could be found down between 60 to 150cm in the south of the region and about half this depth in the north. This crust may have surface hoar on it. The mid-January rain crust and/or surface hoar layer is down over 160cm in the south and has generally become inactive. The November crust/facet combo near the bottom of the snowpack is still on my radar as a potential problem layer in the far north of the region.

Régions couvertes