Avalanche forecast

Kootenay Boundary

Jan 30 – 31, 2015Avalanche Canada
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Avalanche danger

Sun
Mon
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

A strong melt-freeze crust has developed on all but the highest elevation shaded aspects.

Avalanche problems

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–4
    Persistent slab avalanches have become less likely since the surface crust has formed. The mid-January weak layer may be triggered on solar aspects when surface is moist or wet, or in areas where the surface crust is not supportive.

Confidence

Good

Weather Forecast

Freezing level dropping to valley bottoms overnight and not expected to rise above 600 metres on Saturday, or for the rest of the forecast period. Northwest winds developing on Saturday as cloud and very light precipitation move into the region from the coast. There is a chance of a sunny break on Saturday afternoon. 5-10 cm of snow is expected on Sunday combined with strong Westerly winds. Expect a break in the precipitation during the day on Monday, followed by another 5-10 cm of snow on Monday night combined with strong Southwest winds.

Avalanche Summary

There are no new reports of avalanches. The large (size 3.5) natural avalanche reported earlier in the week from the SE aspect of Mt Ymir was found to have released on the mid-December DPWL (deep persistent weak layer) rather than the mid-January PWL (persistent weak layer) that we initially thought was the sliding layer.

Snowpack Summary

Overnight freezing down to valley bottoms has created supportive melt-freeze crusts that have been reported on all aspects up to about 2400 metres. A new layer of surface hoar has been reported to be developing. The top 5-10 cm of surface snow has been moist during the day due to strong solar radiation. The mid-January weak layer of buried surface hoar is down about 20-50 cm and continues to give planar results in snow profile tests. The mid-December crust/facet/surface hoar layer is down 50 cm in low snowpack areas and down about 100 cm in deeper snowpack areas.

Regions covered