Bulletin d’avalanche

Purcells

Feb 15 – 16, 2013Avalanche Canada
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Archivé · expiré 14 years ago

Danger d’avalanche

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

Forecast new snow is expected to add a new load above the recent storm snow that may cause the buried February 12th weak layer to continue to be reactive.

Problèmes avalancheux

  • Wind Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    Wind slabs may be reactive to light loads like skiers or snowmobiles. Areas of concern are steep open slopes immediately lee of ridges and terrain features. New soft wind slabs may develop with the next pulse of moisture.

  • Persistent Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Possible
    Taille
    2–5
    There are a couple of older layers of buried surface hoar and crust combinations that are buried down about 70 cms and 100 cms, that may be triggered by large additional loads.

  • Storm Slabs

    • Alpin
    • Limite forestière
    • Sous la limite forestière
    Probabilité
    Likely
    Taille
    1–4
    The new storm slab may be easy to trigger where it is sitting on a layer of buried surface hoar and/or a sun crust. This storm slab may be very soft (fist hardness) in some areas.

Confidence

Fair - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

Overnight and Saturday: Moderate Westerly winds are expected as the ridge of high pressure flattens and a trough moves into the interior from the Northwest. Alpine temperatures should stay a few degrees warmer than seasonal overnight as the warm front delivers 3-5 cms. Moderate snow fall should start sometime in the early afternoon when the trailing cold front moves across the region. Expect 6-12 cms with cooler temperatures and gusty West winds.Sunday: Unsettled cool air will be left behind as the next ridge of high pressure builds over the interior. Expect light Northerly winds and alpine temperatures down to about -10.0.Monday: Mainly cloudy as the weak ridge of high pressure moves to the East.

Avalanche Summary

Some natural avalanche activity up to size 1.5 was reported from the region on various aspects in steep wind loaded terrain.

Snowpack Summary

There is a lot of variability in the depth of the new snow slab and the new wind slabs. Areas that received 30-40 cms of new snow have developed thick new wind slabs at higher elevations that may be triggered by light additional loads. The storm slab in these areas has been reported to be reactive to skiers, as it slides easily on a layer of surface hoar that developed just previous to the latest storm. In some areas there is a sun crust that developed during the sunny weather last weekend that is a smooth and fast sliding layer for the new storm slab. Deeper weak layers continue to show planar results in snow profile tests down about 70 cms and also at about 100 cms. These deeper layers are less likely to be triggered by skiers, but cornice falls or other large triggers may step down and result in large avalanches.

Régions couvertes