Lawinenlagebericht

South Columbia

Feb 21 – 22, 2016Avalanche Canada
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Archiviert · abgelaufen 11 years ago

Lawinengefahr

Tue
Wed
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

Small weather inputs (sun, snow, or wind) could make buried persistent weaknesses more reactive to human triggering. Conservative terrain choices are essential.

Lawinenprobleme

  • Cornices

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–4
    Natural cornice falls may trigger storm slab avalanches on the slopes below. Periods of strong solar radiation may increase the likelihood of natural cornice falls.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    2–5
    The February 10th surface hoar continues to allow for long fracture propagations resulting in very large avalanches. Strong solar may increase likelihood of triggering.

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    1–3
    Weak bonds may exist within the recent storm snow. Storm slabs in motion may step down to the persistent weak layer resulting in very large avalanches. 

Confidence

Moderate

Weather Forecast

Monday: Cloudy with flurries in the morning and sunny breaks in the afternoon. The freezing level is around 1500 m and ridge winds are light from the NW. Tuesday: Mainly sunny. The freezing level is around 1500 m and ridge winds are light from the W-SW. Wednesday: Mainly sunny. The freezing level is around 1600 m and ridge winds are light to moderate from the W-SW.

Avalanche Summary

Several size 1 loose wet and loose dry avalanches were reported on steep slopes on all aspects on Saturday. Specific wind loaded features were also reactive to skier testing, generally producing size 1-2 slabs. There was also a report of a size 1.5 snowmobile triggered slab avalanche from a treeline feature in the Southeast corner of the region on Saturday. Throughout last week there were reports of natural and human triggered slab avalanches up to size 3 each day, with a fairly widespread natural avalanche cycle observed on Thursday and Friday.

Snowpack Summary

Expect the surface to be a mix of dry snow on shady slopes, wind-affected snow in exposed terrain, and a sun crust/moist snow on solar aspects depending on the time of day. 60-90 cm of settled storm snow sits on a melt-freeze crust. In some areas there is a weak layer of surface hoar at the interface between the storm snow and the crust. The bond between the crust or surface hoar remains suspect, but there are also weaknesses reported within the top layers of the recent storm snow. Moderate winds have created areas of wind slab in the lee of west or southwest winds that may be close to a metre deep. Wind slabs in motion may trigger the persistent weak layer on the crust and result in wide propagations and very large avalanches. Surface hoar buried in early January now lies up to 200cm below the surface and has become less of a concern. Possible triggers for this deep and destructive layer include a large cornice fall, strong sunshine, or significant warming.

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