Avalanche forecast

Purcells

Dec 14 – 15, 2015Avalanche Canada
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Archived · expired 11 years ago

Avalanche danger

Wed
Thu
Alpine
2 · Moderate
Treeline
2 · Moderate
Below
2 · Moderate
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Highlights

The danger has come down, but large human triggered avalanches remain possible. Start with small test slopes and build up slowly to the bigger terrain features. There is still a lot of uncertainty associated with this early winter snowpack.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–4
    A layer of buried surface hoar can be found at and below tree line and remains sensitive to human triggering. It is most widespread between 1400m and 1800m. A buried sun crust and facets can be found in the alpine.

Weather Forecast

A northwest flow will bring light snowfall, and cool temps throughout the forecast period. TUESDAY: Flurries bring up to 2cm of snow, light northwest winds, -5 at 1500m. WEDNESDAY: More flurries for the central Purcells, northwest winds, THURSDAY: Overcast, light northwest winds.

Avalanche Summary

Avalanche activity appears to have tapered off since Friday. Reports from over the weekend describe mainly small explosively controlled avalanches in steep terrain. The exception was a small skier triggered avalanche that ran on the December 2nd surface hoar near in the Panorama slack country. On Friday two significant observations were reported: The first was a natural size 3.5 avalanche that was observed on a SE facing feature at 2800m in the Bugaboos. It ran to ground in some places. The second was a report of a skier triggered size 2.5 avalanche in the DogTooth range that was accidentally triggered on an east facing feature at 1500m. This avalanche failed on the early December Persistent Weak Layer.

Snowpack Summary

Between 35 to 80cm of snow fell last week in the Purcells. You may find a thin crust about 10 to 30cm below the snow surface as high as 1800m. Below the new snow lies the early December persistent weak layer. This layer may be found as either an old sun crust on south facing features in the alpine, or as large grained surface hoar and small facets in isolated pockets especially between 1400m and 1800m. Recent test results on this interface have been widely variable. "Resistant planar," "sudden collapse" and even "no result" have been reported from test profiles as recently as Dec. 13th. All the variation in trigger sensitivity makes this layer tricky to manage. The mid and lower portions of the snowpack are thought to be well settled although a basal weakness may be lurking on high elevation alpine features.

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