Lawinenlagebericht

Purcells

Jan 3 – 4, 2014Avalanche Canada
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Archiviert · abgelaufen 13 years ago

Lawinengefahr

Sun
Mon
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. Check 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
    A weak layer buried around 60 cm has become reactive and can be readily triggered, especially at higher elevations on a variety of aspects.

  • Storm Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    1–4
    The storm snow in conjunction with strong NW winds will likely continue to overload weak layers in the upper meter of the snowpack. Many slopes are primed for human triggered avalanches, particularly on exposed lee aspects at and above treeline.

  • Deep Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Likely
    Größe
    2–6
    The most likely place to trigger a deeper layer is on a steep, convex, north-facing slope in an area with a relatively shallow snowpack.

Confidence

Fair

Weather Forecast

A strong northwesterly flow prevails as an upper ridge establishes itself offshore. Winds will be the most important feature to watch over the next 24 hours. No precip in the forecast for the next 72 hours.Friday: Precip: 3/6mm - 5/10cmSaturday: Freezing Level: Valley Bottom; Precip: Nil; Wind: Mod NW, Strong/Extreme NW at ridgetop. Sunday: Freezing Level: Valley Bottom; Precip: Nil; Wind: Light Variable, Mod NW at ridgetop.Monday: Freezing Level: Valley Bottom, potential for an slight inversion at ridgetop. Precip: Nil; Wind: Light Variable, Strong NW at ridgetop.

Avalanche Summary

A number of significant avalanches have been reported from the north of this region and just beyond its boundary to the north. One very large (size 3) avalanche was reported on Tuesday on a N aspect at 2200 m from relatively gentle terrain with a fracture depth of 100 cm. Two large (size 2) avalanches were reported from near Golden on Monday, likely triggering buried surface hoar from 10-Dec down around 50 cm. A size 3 natural avalanche was reported from the Bugaboos on Sunday on a NE aspect at 2650m, triggered by a cornice release that pulled out a large slab all the way to ground on the slope below. Outside the boundary of this region to the north of Golden, there was an incident in the Hope Creek drainage, where four people were involved (with two sustaining injuries) in a size 3 avalanche in an alpine feature on a NE aspect. Avalanche activity began to pickup on Thursday during the storm.  Check back tomorrow for more details.

Snowpack Summary

Thursdays 10 - 20 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 upper one comprises surface hoar and is buried around 50-70 cm. The lower one comprises a facet/crust combo and is buried 90-120 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 10 days 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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