Avalanche forecast

Kootenay Boundary

Feb 11 – 12, 2014Avalanche Canada
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Avalanche danger

Thu
Fri
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

Avalanche problems

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    1–4
    Loading from the weight of new snow, windloading from extreme southwest and west winds and from rising temperatures is expected to trigger natural slab avalanches tomorrow. Loose snow avalanches are also a concern.

Confidence

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

Weather Forecast

Tonight and Wednesday: Moderate to heavy precipitation is expected tonight and tomorrow. 15-20 cm of snow is forecasted and freezing levels rising to 1200 m in the afternoon. Winds are forecasted to be extreme from the southwest and switching from the west. Thursday: Light to moderate amounts of precipitation are forecasted, in the 15 cm range with moderate to strong westerly winds. Freezing levels are expected to fall to the surface before rising again to 1500 m in the afternoon.  Friday: More unsettled weather as the zonal flow persist. Expect similar precipitation amounts, winds and freezing levels.

Avalanche Summary

Multiple skier triggered slab avalanches size 1 were reported yesterday in the recent snow. Some of these slabs ran on the late January crust interface on east aspects. There was also some sluffing out of steep terrain. Expect more and bigger avalanches this week with the incoming weather.

Snowpack Summary

15-20 cm of snow is expected to fall tonight and tomorrow adding to the 10-15 cm snow already fallen. Extreme winds from the southwest and then from the west will overload lee slopes likely producing large natural avalanches on east and northeast aspects in the alpine and at treeline. Rising temperatures during the day could also weaken the storm snow on all aspects, at all elevations. The storm snow is sitting on a variety of weak layers that formed during the recent cold snap; surface facets, a new surface hoar layer in sheltered areas, a crust on solar aspects or hard windslabs in the alpine. 30-50 cm below the surface, exist a surface hoar or suncrust layer that has been reactive to skier traffic even since it has been buried in late January. Anticipate that there is a good chance that avalanches will step down to this deeper buried weak layer, resulting in bigger than expected storm avalanches. The mid snowpack is strong and supportive. Deeper persistent layers have been dormant, however, they could wake up in the near future with the increasing load.

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