Lawinenlagebericht

South Rockies

Dec 31, 2017Avalanche Canada
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Archiviert · abgelaufen 9 years ago

Lawinengefahr

Mon
Tue
Hochgebirge
3 · Erheblich
Waldgrenze
3 · Erheblich
Unterhalb
3 · Erheblich
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Kernpunkte

Conditions are primed for human triggered avalanches: There's a buried weak layer in the snowpack, with a critical amount of recent storm snow sitting on top. Conservative terrain choices are key for safe riding this weekend.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Unlikely - Possible
    Größe
    1–3
    A weak layer composed of surface hoar and/or crusts is buried 40-80 cm below the surface.

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–2
    Expect sluffing in steep terrain and touchy storm slabs especially in areas that have been loaded by wind. These slabs may be easily triggered by both human and natural triggers.

Confidence

Moderate - Due to the number of field observations

Weather Forecast

Dry with cool temperatures for the foreseeable future. SUNDAY: Mostly sunny. Ridge wind light southwest. Temperature -14. Freezing level surface.MONDAY: Mix of sun and cloud. Ridge wind light southwest. Temperature -12. Freezing level surface.TUESDAY: Mix of sun and cloud. Ridge wind light west. Temperature -12. Freezing level surface.

Avalanche Summary

On Saturday several natural and human triggered storm slab avalanches to Size 2 were reported on a wide variety of aspects and elevations. Furthermore, several persistent slab avalanches to Size 1.5 were reported (with some remote-triggered by skiers). Earlier in the week, a larger persistent slab (Size 2) was triggered low on a slope that propagated up and across the slope on a 50 cm deep crust. This highlights the potential for persistent slab avalanches to have wide propagations.

Snowpack Summary

Up to 45 cm of snow has fallen over the past 2 days, with generally light winds. That said, some areas of the region (Crowsnest Pass) saw strong east winds while others (Elk valley) had lower snowfall amounts. In wind exposed areas this new snow overlies variable wind slabs up to 80 cm thick in some areas. In sheltered areas, 30-60 cm of unconsolidated old storm snow has been covered.The main question in the snowpack surrounds the mid-December layer sitting beneath the recent snow. This layer includes crusts on solar aspects and feathery surface hoar in sheltered terrain at and below treeline, and has produced whumpfing as well as moderate, sudden results in recent snowpack tests. The lower snowpack is composed of mostly soft sugary snow and a few early season crusts that have not produced significant test results recently.For an update on recent conditions check out the Mountain Information Network (MIN) report here. And please post your own reports!

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