Lawinenlagebericht

South Rockies

Jan 10 – 11, 2012Avalanche Canada
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Lawinengefahr

Thu
Fri
Hochgebirge
3 · Erheblich
Waldgrenze
2 · Mässig
Unterhalb
1 · Gering
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Lawinenprobleme

  • Wind Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible - Likely
    Größe
    1–4
    Winds have shifted from SW to N--expect reverse loading, that is wind slabs building on slopes that were previously to windward.

  • Persistent Slabs

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Possible
    Größe
    1–6
    At least two distinct surface hoar layers lie buried up to 80 cm below the snow surface. Triggering these layers has become difficult and isolated to steep, shallow rocky start zones; however the destructive potential of a slide would be high.

  • Loose Wet

    • Hochgebirge
    • Waldgrenze
    • Unterhalb der Waldgrenze
    Wahrscheinlichkeit
    Very Likely
    Größe
    1–3
    New snow on the surface will shed on steep slopes in direct sunlight.

Confidence

Good - -1

Weather Forecast

A ridge of high pressure should bring clear, sunny skies for Wednesday through Friday. Winds will initially blow from the north and then should become westerly or northwesterly on Friday. Freezing levels should stay at valley bottom, although some warming is possible in the region on Friday.

Avalanche Summary

Small loose snow avalanches were reported from the region on Tuesday in the new snow. A sled-triggered size 3 slab avalanche was reported from the Flathead/ Lodgepole area on Saturday. The slide was 75cm deep and 100m wide and occurred on a northeast aspect at the 2100m elevation.Size 1.5 loose snow avalanches were reported in the Elkford area on Saturday.

Snowpack Summary

The average HS (height of snow) in the Crowsnest North is 130cms and the Crowsnest South has 160cms. As we move further West into the Elk Valley North the HS is an average of 140cms. The Elk Valley South sits at 180cms.In the Flathead the avg. HS is 180cms. All snow depths indicated are at the 2000m elevation.A nice dump of around 20 cm of low density new snow arrived Monday night. Northerly winds will redistribute this onto lee slopes, setting up reverse loading on slopes that were previously to windward around ridge crests and other exposed terrain features. The upper slab is still relatively unconsolidated - the cooler temperatures will maintain this situation for a little while to come.In the mid pack, weak buried surface hoar layers can be found on North-NE slopes at treeline and below down approx. 30-55cms. The surface hoar may co-exist with facets that are result of the early December dry spell. This interface is still reactive and has produced numerous natural avalanches over the past week.At the bottom of the snowpack a variable facet/ crust/ facet sandwich is located with depth hoar up to size 5mm below the crust, and facets size 2mm above. There has been little in the way of recent activity on basal layers, but the nature of a release would be highly destructive.As a side note, the snow depths alone indicate that the region is highly variable in terms of snowpack structure. You should anticipate that layering and reactivity of weaknesses will also be variable throughout the region.

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