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Avalanche Forecast

Dec 3rd, 2016–Dec 4th, 2016
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
3: Considerable
The avalanche danger rating at treeline will be considerable
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
3: Considerable
The avalanche danger rating in the alpine will be considerable
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low
Alpine
2: Moderate
The avalanche danger rating in the alpine will be moderate
Treeline
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
1: Low
The avalanche danger rating below treeline will be low

Regions: Sea To Sky.

Forecast snowfall amounts are highly variable for Saturday night with highest amounts expected in the south of the region. Pay close attention to how much snow falls in your riding area, and be prepared to back off to mellow terrain.

Confidence

Moderate - Forecast snowfall amounts are uncertain on Saturday

Weather Forecast

Saturday night and early Sunday morning: 5-15cm of new snow / Strong southwest winds / Alpine temperatures at -8. Sunday: Generally clearing skies / Light north winds / Alpine temperatures at -12. Monday: Clear skies / Light variable winds / Alpine temperatures at -12. Tuesday: Clear skies / Light north winds / Alpine temperatures at -14

Avalanche Summary

At the time of publishing this bulletin, avalanche observations were highly limited. With the new snow and strong southwest winds on Friday night, I'm sure there was evidence of wind slab activity at treeline and in the alpine, especially in the south of the region (Tantalus/ Diamond Head/ Tricouni) where snowfall amounts were greatest. Looking forward to Sunday, continued snowfall and strong winds will continue to promote ongoing wind slab activity.

Snowpack Summary

As of Saturday about 15cm of recent storm snow had been redistributed by strong southwest winds into reactive wind slabs in higher elevation terrain. With more snow and wind forecast for Saturday night, this developing slab will only increase in size and destructive potential. Below the recent storm snow you may find a layer of buried surface hoar which formed during last week's clear weather, although the size and distribution of this layer is largely unknown at this time. The mid-November melt-freeze crust is widespread and is buried anywhere from 20-200 cm depending on aspect and elevation. Although snowpack tests have shown this layer to be mainly unreactive, I'd expect increased reactivity with this layer in shallow, wind-affected alpine start zones.

Avalanche Problems

Wind Slabs

Strong winds and new snow forecast for Saturday night will add to an ongoing wind slab problem. I expect high alpine terrain to get blasted by the wind, so the best and safest skiing may be in lower-elevation, sheltered terrain.
Be cautious as you transition into wind affected terrain.Be aware of the potential for wide propagations due to the presence of hard windslabs.Stay off recent wind loaded areas until the slope has had a chance to stabilize.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Likely - Very Likely

Expected Size: 1 - 2