Lawinenlagebericht

South Columbia

Feb 8 – 9, 2015Avalanche Canada
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Archiviert · abgelaufen 12 years ago

Lawinengefahr

Tue
Wed
Hochgebirge
4 · Gross
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

Storm problems will persist on Monday, especially at higher elevations. Conservative decision making remains critical and travel in avalanche terrain is not recommended.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    3–6
    Buried persistent weak layers have become reactive with heavy storm loading resulting in very large avalanches up to 1.5m deep.

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely - Very Likely
    Größe
    2–5
    Strong winds, heavy snowfall, and high freezing levels have created widespread storm slabs at higher elevations. Continued storm conditions will add to these highly reactive slabs.

  • Wet Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    2–5
    Continued rain at lower elevations may result in wet slab avalanches running to valley bottoms. Loose wet avalanches are expected from steep terrain features.

Confidence

Fair - Freezing levels are uncertain on Tuesday

Weather Forecast

The last major frontal system will reach the interior Sunday overnight. On Monday, the region is expected to see 10-15mm of precipitation. Freezing levels should drop to around 500m Sunday overnight but should rise back to around 1600m on Monday. Alpine winds are expected to be moderate-to-strong from the SW. On Tuesday, things should dry out as a ridge of high pressure builds but mostly cloudy conditions are expected and lingering flurries are possible. Freezing levels should remain around 1500m and alpine winds should be light. A mix of sun and cloud is expected for Wednesday with unseasonably high freezing levels persisting. However, during the overnight periods, temperatures should drop and we should see spring-like diurnal temperature cycles.

Avalanche Summary

Widespread natural, human-triggered, and explosive controlled avalanches up to size 3 were reported on Friday and Saturday. This includes both storm slabs and persistent slabs. Many avalanches started dry and ended wet, running to valley bottom. On Monday, natural avalanches remain likely at upper elevations where storm and wind loading continue. At lower elevations which have seen rain, natural activity is less likely but remains possible. Human-triggering remains very likely at higher elevations on Monday.

Snowpack Summary

50-80cm of recent storm snow has fallen over the late-Jan weak layer at higher elevations. Rising freezing levels during the storm have created upside-down snow conditions and highly reactive storm slabs. Rain has soaked the snow surface up to around 1900m and moist snow is reported to at least 2200m. Strong SW winds have formed wind slabs in exposed leeward terrain features. The storm slab sits on an old rain crust at lower elevations, variable surface hoar, and/or wind affected surfaces at higher elevations. There are also several weaknesses reported within the storm snow. The mid-January surface hoar is typically down 80-120cm and is still reactive in some areas. The mid-December weak layer is down close to 1.5m. It has generally been unreactive but may wake-up with the new storm loading.

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