Avalanche forecast

Northwest Coastal

Feb 3 – 5, 2012Avalanche Canada
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Avalanche danger

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

Highlights

Warm temperatures in alpine areas could cause large, unexpected avalanches, especially on south-facing slopes.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible - Likely
    Size
    3–7
    Cornices are expected to become weak with continued warm temperatures and solar radiation.
  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    2–6
    Rain and warm temperatures have promoted recent avalanche activity at low elevations that has run on a layer of facets buried around 20-Jan. This problem may creep higher in elevation with continued warm alpine temperatures.
  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    3–7
    Recent rain and warm temperatures have promoted avalanche activity on storm slabs. Alpine temperatures are expected to remain high and this problem is expected to continue through the forecast period.

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Saturday and Sunday: Dry or very light flurries, with alpine temperatures around -2C. Winds expected to be light southwesterly rising to moderate southeasterly. Monday: Clear with sunny spells. Temperatures below freezing at low elevations but alpine areas may see inversion conditions that will elevate temperatures to near zero.

Avalanche Summary

On Friday, slab avalanches up to size 3.5 were reported in response initially to rain and then during the day to intense solar radiation. On Thursday, numerous large (up to size 3) slab avalanches were reported out of lee terrain (SW predominantly) along Bear Pass during the warming period as the snow turned to rain. Lower elevations were especially active.

Snowpack Summary

Total snowpack depths pushing 5m at treeline are at new record levels for this time of year. Recent warm temperatures helped settle storm snow into a touchy surface slab at lower elevations. Other weaknesses can be found within the upper snowpack and the Jan. 20th facets down around 150cm. These create the potential for large step-down avalanches, but things seem to be settling rapidly. Strong winds associated with recent storms means large weak wind slabs and cornices on lee and cross-loaded terrain. Most snowpack concerns are limited to the surface layers. However, large triggers such as cornice falls and smaller avalanches stepping-down could affect deeper weaknesses.

Regions covered