Avalanche forecast

South Coast Inland

Mar 17, 2017Avalanche Canada
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Avalanche danger

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

Fresh snow will be touchy in wind affected terrain on Friday, while another wet storm is lined up to elevate the danger this weekend.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely
    Size
    1–2
    The new snow with strong alpine winds has likely formed fresh wind slabs at higher elevations. These slabs will sit over a crust in many areas and are expected to be touchy. Cornices are also reported to be large and may still be weak.

  • Persistent Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Unlikely - Possible
    Size
    2–4
    A weak layer down around 1 metre is creating a low probability/high consequence scenario. It is unlikely to directly trigger this layer but a small avalanche or cornice fall could still step down to it.

Confidence

Moderate - Track of incoming weather systems is uncertain on Saturday

Weather Forecast

FRIDAY: Isolated flurries before the next storm arrives Friday evening, strong southwest winds, alpine temperatures around -7 C.SATURDAY: Storm starts Friday night and delivers 15-25 cm, strong southwest winds, freezing level up to 1500 m with alpine temperatures around -4 C.SUNDAY: Clearing skies following the storm as alpine temperatures drop to around -10 C, moderate west winds.

Avalanche Summary

On Wednesday, evidence of a recent widespread natural avalanche cycle was reported in the northern part of the region. The avalanches included several size 2-3 storm slabs, a number of which stepped down to weak layers over a metre deep. Large cornice failures were also reported. One small skier triggered avalanche was reported on a north-facing wind loaded feature at 1950 m. There are no recent reports from the southern part of the region.On Friday, the most recent snow is expected to form new wind slabs in exposed terrain that may bond poorly to a buried rain crust. It has become difficult to trigger the February weak layers but there is still a chance that a smaller wind slab avalanche or a cornice fall could still step down and release a persistent slab avalanche.

Snowpack Summary

By Friday morning expect 10-20 cm of recent snow sitting above a widespread layer of wet snow up to about 2100 m. The wet snow layer is likely turning into a crust and may become a weak layer as storm snow accumulates. Strong south winds are likely forming wind slabs in the lee of exposed terrain, which may bond poorly to the crust. In the north of the region, the February weak layers are now down 80-120 cm. The layer of buried surface hoar has recently produced a few persistent slab avalanches. The crust/facet layer appears to be gaining strength but may also still be reactive in isolated areas. In the Coquihalla area, the crust/facet layer is down well over 1 m and appears to have gone dormant.

Regions covered