Avalanche Forecast

Issued: Nov 15th, 2011 9:07AM

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

ccampbell, Avalanche Canada

Sea To Sky.

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

Poor - Due to limited field observationsfor the entire period

Weather Forecast

Wednesday: 10-20cm of snow expected, with freezing levels around 900m, and moderate to strong southerly winds.Thursday: Another 5-10cm with freezing levels around 500m, and light to moderate southwesterly winds. Friday: Another pulse of significant precipitation is possible, but the timing and track are uncertain.

Avalanche Summary

No reports of avalanches, but I suspect wind slabs and any new storm slabs will be susceptible to human triggering. The size of the ensuing avalanche depends on slab thickness, with slabs thicker than 30cm generally producing avalanches sufficiently large to bury or injure a person.

Snowpack Summary

Total snowpack depth at treeline is around 60-80 cm, while many alpine areas have over a metre. Expect to find deeper pockets of wind-blown snow immediately down-wind of terrain features and ridge crests. Cold temperatures early last week resulted in some faceting, which kept surface snow cohesionless and weakened the bond to a mid-pack rain crust. However, warmer temperatures last Thursday probably helped things settle and strengthen, and may have even resulted in another crust on the snow surface, which would have been buried over the weekend.

Problems

Wind Slabs

Isolated pockets near ridgecrests and terrain breaks may be susceptible to human triggering.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Storm Slabs

Steep slopes with enough snow on the ground to smooth any roughness in areas with sufficiently intense storms to form thick cohesive slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Nov 16th, 2011 3:00AM