Lawinenlagebericht

South Columbia

Feb 22 – 23, 2016Avalanche Canada
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Archiviert · abgelaufen 11 years ago

Lawinengefahr

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

Intense sun exposure will maintain the potential for large destructive avalanches. Conservative terrain choices with low overhead exposure are essential.

Lawinenprobleme

  • Cornices

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–4
    Large and fragile cornices are will likely continue to fall of ridgecrests with sun exposure and temperature fluctuations. Not only are they a hazard in themselves, but also a heavy trigger for slabs on the slope below.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    2–5
    A weak layer of surface hoar and/or crust down 70-90cm remains susceptible to large triggers such as cornice falls or smaller avalanches stepping down. Wide fracture propagations are likely.

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    1–3
    Recent storm snow is highly sensitive to human triggering and particularly deep and touchy on wind-loaded slopes.

Confidence

Moderate - Freezing levels are uncertain on Wednesday

Weather Forecast

TUESDAY and WEDNESDAY: Mainly sunny and dry with isolated valley cloud dissipating throughout the day. Freezing levels reaching 1500m and light variable winds. THURSDAY: Mainly sunny and dry with isolated valley cloud dissipating throughout the day. A temperature inversion is expected to result in above freezing temperatures well into alpine elevations Winds should remain generally light from the south.

Avalanche Summary

Reports from Sunday include more evidence of natural wind slab avalanches and cornice failures from Saturday, as well as ongoing natural cornice and wind slab activity up to Size 3.5. Human triggering was also reported with skier triggered storm and wind slab avalanches up to Size 1.5 and explosives triggering up to Size 3, a few of which failed on surface hoar down 60-70cm.

Snowpack Summary

10-20cm of new snow on Sunday night buried surface hoar and/or sun crust in most places. Weaknesses exist within 60-90 cm of settled recent storm snow, which is sitting on a crust buried on February 10th. 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. 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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