Avalanche Forecast

Issued: Dec 15th, 2013 4:46PM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is low. Known problems include Wind Slabs and Deep Persistent Slabs.

conrad janzen, Parks Canada

Banff Yoho Kootenay.

Increased hazard due to moderate W winds, continued light precipitation and mild temperatures is present especially in areas near the divide where more snow fall has occurred. Minimize exposure to wind loaded areas over the next few days. CJ

Summary

Weather Forecast

Continued moderate to strong West winds, light precipitation, and alpine temperatures between -5 and -10'C are forecast over the next three days with a cooling and clearing trend beginning on Wednesday.

Snowpack Summary

25cm of storm snow is present near the divide. Moderate to strong W winds and mild temperatures have formed wind slabs in open areas at tree line and above. The mid pack is facetted but still dense enough to support the weight of a skier in many areas. The October melt freeze crust or a mix of depth hoar and facets is present at the base.

Avalanche Summary

One size 2 natural avalanche slid over the "Heineken Hall" ice climb on Mt Dennis today reaching the bottom of the run out zone. Several size 1 moist sluffs were also observed in the Field area out of steep tree line terrain. One size 2 was observed yesterday on the "Sacre Bleu" ice climb on Mt Rundle. Wind appears to be the trigger in all cases.

Confidence

Intensity of incoming weather systems is uncertain

Problems

Wind Slabs

Moderate to strong W winds, mild temperatures and light snowfall are creating wind slabs in open areas at tree line and in the alpine which are beginning to fail naturally in steep alpine terrain and are susceptible to human triggering.

Minimize overhead exposure; avalanches triggered by wind loading may travel long distances.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Deep Persistent Slabs

20-25cm of storm snow combined with mild temperatures and wind may start causing failures in the deeper basal facets or on the Oct melt freeze crust. Use caution in steep terrain.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Dec 16th, 2013 4:00PM