Avalanche forecast

South Columbia

Mar 3 – 4, 2016Avalanche Canada
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Avalanche danger

Sat
Sun
Alpine
3 · Considerable
Treeline
3 · Considerable
Below
2 · Moderate
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Highlights

Storm slabs are highly reactive to human-triggering and conservative terrain selection remains critical for the next few days. Extra caution is required on south-facing slopes in the afternoon if the sun pokes out.

Avalanche problems

  • Cornices

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–5
    Warm temperatures, strong winds, and possible sunny breaks are all factors that could weaken large droopy cornices. 

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–5
    Heavier triggers such as cornice falls, groups of people, or smaller avalanches stepping down, or lighter triggers (such as a person) in the wrong spot may be enough load to trigger a crust and/or surface hoar layer down around a metre.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    1–4
    Fresh storm slabs are primed for human triggering. Particularly touchy wind slabs are lurking below ridge crests, behind terrain features and in cross loaded gullies.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

FRIDAY: Cloudy with sunny breaks and light precipitation starting late in the day. Freezing levels reaching 1600 m late in the day with moderate to strong southwesterly ridgetop winds. SATURDAY: Periods of snow bringing another 5-15cm. Freezing levels steady around 2000-2200 m with strong southwesterly ridgetop winds. SUNDAY: Periods of snow. The freezing level is around 1600-1800 m and ridge winds ease to light and variable.

Avalanche Summary

Continued natural and rider-triggered avalanche activity up to size 2 was reported throughout the region on Wednesday. These slides occurred on all aspects, at all elevations, and were generally 30-60 cm deep. Reports from Tuesday include more of the same plus evidence of a widespread natural avalanche cycle that occurred early Monday, primarily in the Monashee Mountains, with avalanches up to Size 3 running on surface hoar buried late February.

Snowpack Summary

40-60 cm thick storm slabs are bonding poorly to on a crust on previously sun-exposed slopes and surface hoar on shady and sheltered slopes. Thicker and touchier wind slabs are lurking throughout exposed terrain at and above treeline. A weak layer of surface hoar and/or a sun crust buried February 21 is now close to a metre below the surface. Where it exists, this layer may become reactive to human triggers as the overlying slab develops. The surface hoar and/or crust layer buried February 10 is likely down over a metre. This layer was less reactive over the weekend with cooler temperatures, but remains a concern for large triggers like cornice falls or a smaller avalanches stepping down. Cornices are large and potentially weak and should be avoided where possible.

Regions covered