Avalanche forecast

Kootenay Boundary

Feb 17 – 18, 2015Avalanche Canada
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Avalanche danger

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

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Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    1–3
    Not only a hazards in themselves, cornice falls can also act as heavy triggers for persistent slab avalanches on the the slope below.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely
    Size
    1–5
    Although unlikely, these highly destructive avalanches remain possible with heavy impacts (e.g. cornice falls and surface avalanche stepping down) in the right spot (e.g. thin rocky areas). Daytime warming will also increase sensitivity.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    Surface snow could loose cohesion and sluff easily on steep sun-exposed slopes in the afternoon. Although small, these wet avalanches could have enough mass to knock you off your feet and take you for a ride.

Confidence

Good

Weather Forecast

Sunny and dry for Wednesday with some cloud cover expected for Thursday and Friday. Above freezing alpine temperatures are expected on Wednesday; however, freezing levels should drop back down to 1600 m  for Thursday and Friday, and valley bottoms overnight throughout the forecast period. Generally light northwesterly winds are expected with a brief shift to southwesterlies as the clouds roll in on Wednesday afternoon.

Avalanche Summary

No new avalanches were reported on Monday or Tuesday morning.

Snowpack Summary

The surface snow is undergoing a melt-freeze cycle with a strong frozen state in the morning followed by a weak melted state in the afternoon, especially on sun-exposed slopes. Not only does surface snow become weak with daytime warming, but slabs lose stiffness making deeper weaknesses more susceptible to triggering. The crust buried at the beginning of February is down around 40-60 cm and generally well-bonded; however, this bond is much weaker where surface hoar overlies the crust. Below that, recent snowpack tests gave moderate to hard but sudden collapse results on the mid-January surface hoar where it was found down 113 cm on a northwest facing alpine slope, as well as moderate sudden planar results where it was found down 55-85 cm at treeline. The mid-December crust/facet/surface hoar weakness may be persisting in the mid to lower snowpack at higher elevations.

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