Avalanche forecast

Kootenay Boundary

Mar 20 – 21, 2015Avalanche Canada
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Archived · expired 12 years ago

Avalanche danger

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

Highlights

New snow with strong winds is expected to form touchy wind slabs.  Use conservative terrain selection and avoid wind-loaded features.  At lower elevations, rain may cause loose wet problems.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Strong winds and new snow are forming wind slabs which are expected to be touchy on Saturday.
  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–3
    Rain at lower elevations will weaken the upper snowpack and increase the likelihood of loose wet avalanches.

Confidence

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

Weather Forecast

A storm system will bring light precipitation to the region on Saturday. Models are currently forecasting 5-10mm. Freezing levels will start at over 2000m but should fall to around 1500m by the end of the day meaning rain may switch to snow at many elevations. Alpine winds are expected to be strong from the SW. On Sunday, a weak ridge of high pressure should build bringing a mix of sun and cloud. Freezing levels are forecast to reach around 2000m and alpine winds should be light. Another storm system should reach the region on Monday bringing light precipitation.

Avalanche Summary

On Thursday, skiers were triggering wet sluffing and natural dry sluffing was reported on steep north facing features. On Wednesday, natural and skier-triggered sluffing was reported from steep sun-exposed slopes. On Saturday, wind loaded areas are the biggest concern. New wind slabs will likely be touchy. Loose wet avalanches are a problem at lower elevations where it is raining.

Snowpack Summary

Recent snowfall may be sitting on a sun crust on solar aspects. During the heat afternoon of the afternoon, the snow surface has been reported to be moist or wet at all elevations on solar aspects and up to 2000m on north aspects. At many elevations, melt-freeze cycles are occurring with a weak surface crust forming overnight and then breaking down during the afternoon. Up to 35cm of snow from last weekends storm sits over the mid-March rain crust which is up to 15cm thick. Reports suggest that this snow is bonding well to the crust. Older deeply buried persistent weak layers still exist in the snowpack but are no longer expected to be reactive.

Regions covered