Avalanche forecast

Kootenay Boundary

Mar 10 – 11, 2016Avalanche Canada
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Avalanche danger

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

Intense solar radiation is expected to keep avalanche danger elevated tomorrow. Continued natural avalanche activity is possible.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    2–5
    Direct sun-exposure is expected to weaken large droopy cornices. Not only are massive cornice falls a hazard in themselves, but they can also act a heavy trigger for slab avalanches on the slope below.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–4
    Particularly deep and touchy on wind-loaded slopes at higher elevations. Expect increased sensitivity to triggering with sun-exposure.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain on Friday

Weather Forecast

FRIDAY: Mainly sunny and dry with freezing levels back up to 1800m. Clouds are expected to roll back in early afternoon and winds should remain light to moderate southeasterly to southwesterly. SATURDAY Mainly cloudy with snow flurries bringing another 5-15cm. Freezing levels hovering around 1800m and moderate to strong southwesterly ridgetop winds. SUNDAY: A mix of sun and cloud, with light flurries. Freezing levels dropping back down to 1700m and moderate to strong southwesterly ridgetop winds.

Avalanche Summary

Reports from Wednesday include isolated harmless skier-triggered storm slab avalanches and one natural Size 1.5 on a northeast aspect at 2150m. Of note was a 50-60cm deep Size 1.5 persistent slab avalanche running on the late February surface hoar, which was ski-cut from the top of a ridge into a steep north facing chute. It propagate the full width of the chute and ran to the bottom. Initial reports from Thursday include several natural and explosives controlled Size 1.5-2 storm slab avalanches. Widespread natural avalanche activity is likely in response to heavy loading from snow, wind and rain.

Snowpack Summary

Another 15-25cm adds to the 35cm of recent snow that is bonding poorly to a widespread rain crust which extends into alpine elevations. A persistent weak layer buried late-February is now likely down 50-80cm and may still be sensitive to human triggers as indicated by recent avalanche activity and hard but sudden snowpack test results. This weakness is widespread buried surface hoar on sheltered slopes above 1700m, and a crust potentially with associated facets on previously sun-exposed slopes (primarily south aspects). Over a metre down you will likely find the mid-February crust/facet/surface hoar layer, which has been inactive lately.

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