Lawinenlagebericht

Purcells

Jan 4 – 5, 2014Avalanche Canada
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Archiviert · abgelaufen 13 years ago

Lawinengefahr

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

While humans crave simplicity the current situation is anything but. The answer to the avalanche problem this weekend is staying conservative with terrain selection. Visit the blog for thoughts on the recent pattern of accidents in the Purcells.

Lawinenprobleme

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–5
    New snow and fresh wind slabs rest on top of two persistent weak layers in the upper meter of the snowpack. Many slopes are teetering on the edge of failure waiting for a human trigger, particularly exposed lee slopes at and above treeline.

  • Deep Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    2–6
    You wouldn't build a house with a weak foundation and you can't trust a snowpack with this kind of structural weakness near the ground. You're most likely to trigger this layer on steep north through east facing slopes with a shallow snowpack.

Confidence

Good - Freezing levels are uncertain on Monday

Weather Forecast

A strong, stable northwesterly flow will prevail over the province while a strong upper ridge remains offshore. The mountain top winds should ease Sunday as the upper ridge moves over the coast. The ridge will then weaken somewhat on Monday but will still protect the province from Pacific systems.Sunday: Freezing Level: Valley Bottom; Precip: Nil; Wind: Light, Variable. Strong NW at ridgetop.Monday: Freezing Level: Valley Bottom with chance of an Above Freezing Layer from 1500 2500m. Precip: Nil; Wind: Light Variable, Mod NW at ridgetop.Tuesday: Freezing Level: Valley Bottom; Precip: Trace; Wind: Lht Variable.

Avalanche Summary

There have been a few different close calls with large avalanches in the north of this region in the last two weeks. Check out the incident database for more details. On Friday avalanches released naturally and with explosive control resulting in avalanches to size 3.5 with crowns up to 2 meters in depth on all aspects.

Snowpack Summary

Thursdays 20 - 40 cm of storm snow lies on top of old wind slabs and a couple of persistent weak layers that exist in the upper meter of the relatively thin snowpack. The Mid December Surface Hoar is buried around 30-90 cm. The early December facet/crust combo is buried down 50-150 cm. Both interfaces give variable results with snowpack tests, but professional operators are treating them with caution.A bigger concern, especially in the Northern part of the region is a layer of weak sugary depth hoar crystals at the base of the snowpack that lie above a crust from early October. Several large avalanches in the last two weeks have been attributed to failures at this layer. Wide propagations on relatively gentle terrain have been noted, as well as a tendency for seemingly disconnected slopes to become connected by one large avalanche.

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