Avalanche Forecast

Issued: Nov 20th, 2015 4:00PM

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

garth lemke, Parks Canada

Jasper.

Winds will increase moderate to strong WNW Saturday afternoon. With the storm snow still available for transport, this may be the weather that tips the scales to forming widespread windslab conditions. Be vigilant.

Summary

Weather Forecast

Expect seasonal temperatures next few days with a slight warming trend Saturday. A wind event may occur Saturday afternoon into Sunday bringing moderate to strong WNW winds. Monday may bring 20-30cm of storm snow. Be observant the impacts of wind transport and resulting slab development.

Snowpack Summary

Profile at Parkers study plot at treeline 2000m had 90cm snowpack. Top 30cm is low density recent storm snow over slightly more dense midpack. Foot penetration is 50cm. In the field, snow depths vary between 70 to 140 cm in the Icefields. Unsupportive conditions persist below treeline and improve with elevation. Wind slabs forming on lee aspects.

Avalanche Summary

Explosive work on Parkers slabs on Wednesday produced avalanches up to size 2.5. Friday's patrol revealed no new avalanches and visibility was excellent.

Confidence

Wind speed and direction is uncertain on Saturday

Problems

Wind Slabs

After the storm, northerly alpine winds reverse loaded lee aspects. Strong winds since yesterday have been forming new wind slabs on lee aspect slopes. These slabs are sitting on a weakness at the ground, full depth avalanches are possible.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Be cautious as you transition into wind affected terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Loose Dry

50-70 cm of unconsolidated snow is sitting on steep terrain. Expect point releases from cliffs and steep smooth surfaces. Wind, sun and other triggers could release this snow and be enough mass to bury a person or push an ice climber off.

Be cautious of sluffing in steep terrain.Be very cautious with gully features.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Valid until: Nov 21st, 2015 4:00PM