Avalanche forecast

Sea To Sky

Dec 15 – 16, 2016Avalanche Canada
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Avalanche danger

Fri
Sat
Alpine
2 · Moderate
Treeline
1 · Low
Below
1 · Low
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Highlights

Beware of wind-loaded and sun-exposed slopes where the recent storm snow has settled into touchy slabs.

Avalanche problems

  • Wind Slabs

    • Alpine
    • Treeline
    • Below treeline
    Likelihood
    Possible
    Size
    1–2
    Fresh soft and old hard winds slabs may be lurking on all aspects due to recent winds from a variety of directions. The recent storm snow may also have settled into a reactive slab on sun-exposed slopes.

Confidence

Moderate - Wind effect is extremely variable

Weather Forecast

On Friday expect a mix of sun and cloud with light to moderate northerly winds and alpine temperatures around -15. Mainly cloudy for Saturday with moderate northwesterly winds and alpine temperatures around -10. Sunday should also be mainly cloudy with flurries bringing 5 cm of fresh snow by the afternoon. Ridgetop winds are expected to increase to moderate to strong westerlies and alpine temperatures around -10.

Avalanche Summary

No new avalanches were reported on Wednesday. Reports from Tuesday are limited to isolated small sluffs in steep terrain in response to riders and sun-exposure. Reports from Monday include a few Size 1-2 naturally occurring storm slab avalanches on west through southwest aspects in the alpine. On Sunday, a small cornice was human-triggered and loose snow avalanches were noted in steeper terrain. Expect the recent storm snow to be reactive to light triggers in areas where it has settled into a cohesive slab, such as lee slopes near ridgecrests and terrain breaks and sun-exposed slopes.

Snowpack Summary

Surface hoar is growing in sheltered lower elevation areas, and the upper snowpack is faceting. Around 20cm of low density snow recently buried the previous variable snow surface, which includes hard wind pressed or scoured areas, old wind slabs, weak faceted snow, or small surface hoar. The cold temperatures appear to be preserving the old (now buried) wind slabs from the end of last week and they still may be reactive to human triggering in isolated areas. Recent snowpack tests near Whistler gave hard but sudden results in faceted snow under the old hard wind slab. Moderate southwest winds over the weekend and more recent northerly winds have formed soft wind slabs in immediate leeward features. The widespread mid-November crust is typically down 1-2m in the snowpack. Recent snowpack and explosive tests have shown the crust to be unreactive, but it could remain a problem in shallow alpine start zones.

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