Lawinenlagebericht

South Columbia

Jan 24 – 25, 2015Avalanche Canada
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Archiviert · abgelaufen 12 years ago

Lawinengefahr

Mon
Tue
Hochgebirge
4 · Gross
Waldgrenze
3 · Erheblich
Unterhalb
2 · Mässig
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Kernpunkte

High freezing levels with rain and strong winds mean that the snow pack may take time to stabilize. Conservative decision making is still recommended.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely - Very Likely
    Größe
    3–6
    A weak layer of surface hoar crystals is buried between 60 and 90 cm below the surface, on south aspects this layer sits above a crust. This layer will take some time to adjust to the new snow and warm temperatures and can produce large avalanches.

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    2–5
    Warming temperatures and rain with high winds will likely cause avalanches from sufficiently steep terrain in a number of places. At lower elevations the new snow may become saturated and form loose wet avalanches.

  • Deep Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    3–6
    A weak layer buried mid-December is still producing dangerous avalanches over a month after it was first buried. Particularly for slopes around treeline, there is a danger for a small avalanche to step down to this layer increasing the consequences.

Confidence

Poor - Due to the number and quality of field observations

Weather Forecast

A second warm wet weather system will hit the coast on Sunday although a week ridge of high pressure will protect the interior from the brunt of this system and I expect the region will see only light flurries or showers on Sunday. Warm temperatures and moderate to strong SW winds will persist through until Tuesday

Avalanche Summary

Recent snow, forecast rain, warm temperatures and high winds are a recipe for an avalanche cycle, especially when you throw in a couple of prominent weak layers. I anticipate an active cycle to continue on Sunday. Previous avalanche activity during and after the last storm system was widespread, with avalanches releasing up to size 3.5 on a variety of aspects and elevations.

Snowpack Summary

Between 20 and 30 cm of new snow (and possibly rain at lower elevations) fell in the last storm which I suspect is rapidly settling into a soft slab. This new snow sits upon a moderately dense upper snowpack. A weak layer of surface hoar lies buried between 60 and 90 cm below the surface, and may sit above a crust, particularly on south-facing slopes. This "mid-January" weak layer is widespread and has been the main focus for recent avalanche activity. I suspect that it will continue to produce avalanches through the weekend as the snow pack adjusts to the recent snowfall and continued warm temperatures. The still problematic mid-December surface hoar/crust layer is now typically 90-160cm below the surface. While snowpack tests indicate this layer is gaining strength in many areas, avalanches were still noted on this layer from the last storm cycle, which suggests we still need to it into our decision making process. It has been most reactive in the 1600-1900 m elevation band.

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