Avalanche forecast

Kananaskis

Mar 23 – 24, 2016Alberta Parks
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Avalanche danger

Fri
Sat
Alpine
3 · Considerable
Treeline
2 · Moderate
Below
1 · Low
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Highlights

Terrain selection and route finding is key out there. Good situational awareness and discipline are crucial for this week or until the snowpack gets into spring mode. The snowpack is highly complex so do not fool yourself into believing otherwise.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    3–6
    They are much bigger than you, they will trigger monster avalanches based on what we have seen this past 2 weeks - give them LOTS of space and as little of your exposure time as is possible.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–5
    There are multiple melt form crusts in the upper to midpack and are producing variable results in snowpack tests. In spite of bonding interfaces, watch the warming inputs such as solar and increasing freezing levels on wind slabs over these crusts

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    3–6
    Shallow snowpack areas need to be monitored  and avoided as you travel through treeline and alpine terrain.  Really good idea to stay well away from large scale alpine features, especially in the presence of  looming cornices

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

The Jet stream is to the north of the Rockies at moment.  Tonight the winds are forecast to be strong out of the west through the evening.  Winds will taper in the am and the freezing levels are set for 1600 meters with trace precipitation in the next 24 hrs.

Avalanche Summary

Yesterday Banff Visitor Safety Forecasting team did avalanche control on the Bourgeau 4 path and got a size 2.5 slab avalanche result.  Temperatures were cool this morning but freeze levels have been in the 1800-2000 meter range so activity coincides with the sun and warming air in the afternoon.  Pay attention to the daytime heating and any new storm loads over the next while.

Snowpack Summary

We continue to see evidence that our snowpack is not yet a spring snowpack and still very much a winter snowpack.  The upper snowpack is complex with 4-5 melt form crusts that vary in depth from just below the surface and up to 80cm deep.  These melt form crusts, particularly the Feb11th crust are highly suspicious as we saw many large size 2.5-3.0 avalanches out of steep hanging alpine walls. some initiated by cornice failures and others failing with heat (solar or ambient air temperatures approaching zero degrees).  The second and biggest concern for us at the moment is the Jan 6th interface (facets) buried anywhere from 60-110cm in the snowpack - a legitimate deep Persistent Weak Layer.  This is the layer that is associated with the very long drought we had that started shortly after Dec 20th and extended into the 2nd week of January before another storm buried these facets.  This layer is showing highly variable results in snowpack tests and high degree of variability in its distribution.  Essentially we have a very low degree of confidence as forecasters in the snowpack.

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