Avalanche Forecast

Issued: Nov 21st, 2011 9:43AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Wind Slabs and Storm Slabs.

ccampbell, Avalanche Canada

Northwest Coastal.

This bulletin is based on limited data. Local variation in conditions and danger levels are likely to exist. To produce more accurate forecasts, we need information. Please send an email to forecaster@avalanche.ca

Summary

Confidence

Fair - Due to limited field observationsfor the entire period

Weather Forecast

Tuesday: Expect another 30-40cm, especially in southern coastal areas, with freezing levels as high as 700m and strong southwesterly winds.Wednesday: Continued moderate snowfall in southern coastal areas with another 30-40cm possible. Freezing levels back down to valley bottoms and strong southwesterly winds.Thursday: Another pulse of moderate snowfall is expected.

Avalanche Summary

No recent avalanche have been reported, but I suspect natural avalanche activity occurred in response to recent heavy loading from snow and especially wind. I expect natrual avalanche activity to continue as long as it's snowing asn blowing, and the potential for human-triggering to remain for the forecast period.

Snowpack Summary

As of Monday afternoon, recent storm snow totals were in the 30-60cm range. Varying temperature, precipitation intensity, and wind throughout the recent storm, as well as surface hoar on the previous snow surface, has probably resulted in various weaknesses within and under the recent storm snow. Previous storm snow weaknesses could also be lurking in the upper snowpack. The mid and lower snowpack is generally well settled and strong with an old rain crust near the ground.

Problems

Wind Slabs

Near ridge crests and terrain breaks, and in cross-loaded gullies. Heavy loading from wind probably resulted in natural avalanche activity.

Aspects: North, North East, East, South East, South.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

2 - 5

Storm Slabs

Storm slabs are likely very touchy, especially where they are sitting on surface hoar.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 4

Valid until: Nov 22nd, 2011 8:00AM