Avalanche forecast

Purcells

Feb 1 – 2, 2013Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

The weather forecast says that you better put your sun screen on for Saturday! The snow pack doesn’t have sun screen, so it might start peeling off if the sun gets too hot or alpine temperatures get too warm.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–4
    Recent wind slabs continue to be triggered by light additional loads. Wind slabs may become more reactive during periods of strong solar radiation, or if alpine temperatures reach above freezing values.

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    Cornices may not be well anchored. Forecast warm temperatures may cause them to fall off naturally.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1–3
    The recent storm snow continues to settle into a cohesive slab above weak layers and variable old surfaces. This slab may become more reactive during the forecast warm temperatures and solar radiation.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Saturday

Weather Forecast

Overnight and Saturday: Light Northwest winds and thin high cloud overnight with freezing down to the valleys. Light West winds with mostly clear skies with a chance of valley cloud and the freezing level rising up to about 1900 metres. A chance of an above freezing layer in the alpine during the afternoon; chance increases as you move to the South.Sunday: Freezing levels dropping to about 1400 metres and alpine temperatures moving down to about -3.0 as the cloud cover thickens in advance of the next pulse of moisture coming from the coast.Monday: West winds building during the day with light flurries becoming moderate snow by evening.

Avalanche Summary

Natural avalanches size 1.0 have been reported from steep un-supported terrain features.

Snowpack Summary

Westerly winds and warm temperatures overnight have continued to develop wind slabs in the alpine and at treeline. Wind slab was reported to be stiffening from fist to four finger hardness. The recent storm slab has been settling and becoming more cohesive. Pockets of slab that were mostly between 30-50 cms deep above the January 23rd weak layer have started to release naturally or when light additional loads have been added (like ski-cutting). As we head into a warming period expect the recent storm slab to become more reactive. The forecast warm temperatures at higher elevations on Saturday may help initiate releases on the January 23rd layer. The deeper weak layer from January 4th is reported to be gaining strength, and I don't expect that we will see releases on this layer from one day of solar radiation and warm temperatures. That being said, if cornices start to fall off from the heating on Saturday, that might be enough of a load to trigger the deeper January 4th layer.

Regions covered