Avalanche forecast

Cariboos

Feb 22 – 23, 2012Avalanche Canada
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Archived · expired 15 years ago

Avalanche danger

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

Very touchy conditions require very conservative decision making. It's a good idea to avoid all avalanche terrain.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely - Certain
    Size
    2–5
    Strong west-northwest winds will continue to build deep windslabs overlying several persistent weaknesses in the upper snowpack.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–5
    Up to 60cm of settling storm snow overlies several weaknesses including surface hoar and a sun crust. It may be possible to trigger avalanches in surprisingly low-angle terrain.

Confidence

Good

Weather Forecast

Thursday: Mainly dry under a weak ridge of high pressure. Isolated flurries are possible but accumulations should be very light. Friday: Light snowfall - 5-10cm with the greatest amounts likely in the south. Winds should be moderate from the southwest. Saturday: Flurries continue in most areas. Winds should ease to light and variable. The freezing level should remain at valley bottom for the forecast period.

Avalanche Summary

It is likely that a natural avalanche cycle occurred in parts of the Cariboos on Wednesday in response to additional snowfall and strong winds. Previous reports include several natural and skier triggered avalanches up to Size 2.0 These avalanches primarily occurred in wind affected terrain in the alpine, or on steep convex shaped features below treeline.

Snowpack Summary

Wind slabs continue to grow in exposed terrain in response to moderate W-SW winds. 30-60cm of storm snow has now settled into a cohesive slab and overlies the Feb. 9 weakness, which includes surface hoar and/or a crust. This surface hoar layer may be widespread in some areas, while others have reported it being confined to shady aspects at treeline and in the alpine. A melt-freeze crust has developed on solar aspects at all elevations, and on all aspects below about 1600 metres. The mid-pack is generally well settled. There is some concern that large loads like cornices may trigger the Jan. 20th facet layer. Some shallow snowpack areas may continue to have a weak layer of basal facets near the ground.

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