Avalanche forecast

Northwest Coastal

Nov 26 – 27, 2011Avalanche Canada
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Avalanche danger

Mon
Tue
Alpine
4 · High
Treeline
4 · High
Below
3 · Considerable
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Highlights

A series of strong frontal systems will affect the region resulting in HIGH avalanche danger throughout the forecast period. Travel in avalanche terrain is not recommended.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Very Likely
    Size
    2–6
    Expect to find deep and dense wind slabs in exposed terrain well below ridge crests.

  • Storm Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Likely - Very Likely
    Size
    2–5
    Weaknesses may exist within or under the recent storm snow.

Confidence

Fair - Due to limited field observations

Weather Forecast

Snow should ease off on Sunday morning with a freezing level lowering to around 500-600m. Winds should be light to moderate from the W-SW. Another frontal system arrives on Monday bringing heavy snowfall and rising southwesterly winds to most areas through Tuesday morning. 40-70cm of snow is possible with a freezing level around 700m. Precipitation should ease off by Tuesday afternoon.

Avalanche Summary

Recent reports are limited to the highway corridors near Bear Pass and Terrace. Several natural avalanches up to Size 3 were observed, primarily in response to strong westerly winds. Explosive control produced a few Size 2-2.5 avalanches involving the recent storm snow. Both natural and human triggered avalanche activity should remain likely throughout the forecast period.

Snowpack Summary

Heavy snowfall continued on Saturday with some areas reporting more than 50cm of snow by mid-day. The snowpack depth near treeline is already around 300cm. Fluctuating freezing levels and varying precipitation intensity and wind throughout the recent storms has probably resulted in various weaknesses within upper snowpack. Widespread surface hoar was also observed on the previous snow surface at all elevations, but there is no recent information on this layer. The mid and lower snowpack is generally well settled and strong with an old rain crust near the ground.

Regions covered