Avalanche forecast

Purcells

Feb 13 – 14, 2012Avalanche Canada
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Archived · expired 15 years ago

Avalanche danger

Wed
Thu
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–5
    Watch for tender cornices at ridge tops. They may be destructive by themselves, and have potential to trigger large avalanches on the slope below.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3–7
    Although a deep persistent slab would most likely require a large trigger, they are still possible; especially in thin snowpack areas or in unsupported, rocky terrain.

Confidence

Good - -1

Weather Forecast

The wind should change to north by Tuesday morning as more high pressure moves across the interior. Clear skies and strong solar radiation is expected during the day on Tuesday, however northwest winds should help to keep alpine maximum temperatures close to -10.0 on shaded aspects. Some cloud is expected to develop in the afternoon or early evening. Temperatures should drop down to about -15.0 in the alpine by Wednesday morning. The ridge of high pressure is expected to continue to bring clear skies and light winds during the day Wednesday. Alpine temperatures may rise above freezing on solar aspects, but should remain slightly below freezing on shaded aspects. The ridge is forecast to hold on Thursday as the next Pacific system approaches the coast.

Avalanche Summary

Report of one explosive controlled avalanche size 3.5 that stepped down to the basal facet layer at the ground in moraine features. Some other explosive control did not produce any results.

Snowpack Summary

Widespread surface hoar has been buried by a couple of cm of new snow in most of the region. A melt-freeze crust has developed on southerly aspects at all elevations. North and east aspects continue to have dry snow and some surface hoar sloughing in steep terrain. The January 13th surface hoar layer is buried about 40 cm below the surface, and may still be reactive in thinner snowpack areas. Basal facets have not been reactive, but operators continue to monitor this layer in tests. Triggering this deep persistent weak layer is unlikely, but shallow snowpack areas or shallow weak areas adjacent to deeper wind loaded slopes are suspect locations.

Regions covered