Avalanche forecast

Purcells

Feb 2 – 3, 2015Avalanche Canada
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Archived · expired 12 years ago

Avalanche danger

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

A new storm slab is developing. Watch for continued loading from the forecast new snow and wind this week.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    2–5
    A layer of surface hoar buried in the upper meter of the snowpack has been the failure layer for recent natural and human triggered avalanches. Storm slab avalanches in motion may step down to the buried weak layer.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    A new storm slab is developing above a crust and/or surface hoar that was buried in the past few days.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    3–6
    Deeply buried weak layers may react to large loads like an avalanche in motion, or could be triggered by light loads in thin and variable snowpack areas.

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Flurries overnight are expected to bring 2-3 cm by Tuesday morning. Tuesday and Wednesday should be mostly dry with a chance of light flurries. The next storm should start early Thursday morning and at this time looks like it could bring 5-10 cm by Friday morning.

Avalanche Summary

No new avalanches reported. I suspect that the new storm snow may not bond well to the old crust and/or surface hoar, resulting in easy triggering of a thin soft slab.

Snowpack Summary

A thin layer of new storm snow has fallen on a variety of old surfaces, including hard crusts, breakable crusts at higher elevations, and surface hoar in some areas. A melt freeze crust can be found up to about 2200m. At higher elevations, the surface is heavily wind affected. The depth of the mid-January surface hoar is highly variable across the region and it may have been destroyed by warmth at low elevations. Where it does exist, it can be found between 30 and 70 cm below the surface. The mid-December surface hoar layer lies below a strong mid-pack down about 60 to 120cm. Both of these persistent layers have been reactive recently. The mid-November weak layer of crusts and facets can still be found near the bottom of the snowpack. It has been unreactive lately, but should be on your radar in shallow snowpack areas where there is more chance of triggering.

Regions covered