Avalanche forecast

Kootenay Boundary

Feb 17 – 19, 2012Avalanche Canada
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Avalanche danger

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

See forecaster blog for a discussion on changing avalanche conditions.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    New thin wind slabs have developed on exposed lee terrain. The underlying snow surface makes a poor bond to newly forming wind slabs.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    New snow could overload a weak layer buried 20-30 cm below the surface.

  • Deep Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    3–7
    Large avalanches remain a concern in shallow rocky areas where they could be triggered with a very heavy load, such as cornice fall.

Confidence

Fair - Intensity of incoming weather is uncertain on Saturday

Weather Forecast

By the end of Saturday, high snowfall areas in the region could see as much as 20 cm of low density new snow as a frontal system tracks along the US/Canadian border. Moderate southwest winds are expected and alpine temperatures should hover between -5 and -10C. For Sunday and Monday, a series of weak disturbances embedded in a northwesterly flow will bring light precipitation. Winds should be generally light or moderate, with the switch from southwesterly to northwesterly expected to occur on Sunday night.

Avalanche Summary

Wind slab pockets could be triggered on convex rolls on Friday at higher elevations. Two size 2 human-triggered avalanches were been reported from Kootenay Pass on Wednesday/Thursday, initiating on a surface hoar layer down around 15 cm on north east facing slopes below treeline. Things are changing. Check out the forecaster blog for a discussion on scenarios that may play out as the current situation evolves.

Snowpack Summary

Another 5-10cm of snow on Thursday has brought the total to about 15-25 cm of dry snow above the major surface hoar created at the beginning of the month. Some thin windslab may have developed in the alpine due to moderate westerly winds. This interface will be one to watch as it receives more snow load and/or the slab settles. Below that 30cm of near-surface facets can be found on shady slopes while a sun crust can be found on southerly aspects. In shallow snowpack areas concerns remain for the mid-December persistent weakness down around 80-100cm and for basal facets.

Regions covered