Avalanche forecast

Kootenay Boundary

Mar 30 – 31, 2016Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
3 · Considerable
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Highlights

Solar warming will drive the Avalanche Danger throughout the forecast period. Watch your overhead hazard as large and destructive avalanches may reach their run-out zones.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    1–5
    Large fragile cornices threaten many slopes and will become increasingly touchy with solar radiation. A cornice fall could be the large trigger required to awaken destructive buried weak layers.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    3–6
    Intense spring sun and rising temperatures could reactivate buried persistent weaknesses in the mid and upper snowpack. Avalanches at these interfaces could be surprisingly large, so watch your overhead hazard and avoid slopes threatened by cornices.

  • Loose Wet

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–3
    Warming will promote pushy loose wet avalanches at all elevations throughout the forecast period. Multiple crust layers exist on solar aspects making destructive wet slab avalanches a concern as well.

Confidence

High - The weather pattern is stable

Weather Forecast

A well-embedded ridge of high pressure will keep the region warm and sunny for Thursday and Friday, while increased cloud is forecast for Saturday. Freezing levels should hover around 2800m for each day of the forecast period. Ridgetop winds will remain generally light.

Avalanche Summary

A few small wet slabs were observed around Kootenay Pass on Tuesday. They undoubtedly occurred in response to warming and solar radiation. At the time of publishing no other avalanches were reported, although this may reflect a lack of observations rather than actual conditions. The sun has become the main driver for avalanche activity. Although warming has promoted settlement and strengthening within storm snow from last weekend, loose wet avalanches and cornice falls have become the most common avalanche type. A major concern, however, remains isolated yet destructive releases on deeper weak layers which formed earlier in the season (see snowpack description). Avalanches on these layers could run surprisingly long distances, and may be triggered by a cornice fall, a surface avalanche in motion or extended periods of warming.

Snowpack Summary

On shaded slopes above 1900m you'll still find cold winter snow which is reported to be settled and faceted on sheltered slopes, and wind-affected in exposed areas. Warm temperatures have promoted a daily melt-freeze cycle on all other snow surfaces. Cornices are large and looming and have become increasingly weak with the sunny weather. In the upper snowpack you'll likely find a few hard crusts which exist everywhere except on high, north-facing terrain. The late February surface hoar/ crust interface (down 80 to 130 cm) remains a low probability/ high consequence concern. Test results are variable, with occasional sudden planar (pop) results. While generally becoming unlikely to trigger, this layer could produce surprisingly large and destructive avalanches with a cornice fall or warm temperatures.

Regions covered