Avalanche Forecast

Issued: Dec 22nd, 2018 4:00PM

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

deryl kelly, Parks Canada

Jasper.

Over 100cm of snow has fallen in the Ice Fields region since Dec 11. We continue to see wide spread avalanche activity throughout the back country. This is the time to be on high alert when traveling in any avalanche terrain.

Summary

Weather Forecast

A cooling trend has taken hold. Temperatures will gradually "warm", through the weekend with alpine highs near -10C. The sky will be generally a mix of sun and cloud with no precipitation in the near future. Moderate south-west winds forecastedA detailed mountain weather forecast is available from Avalanche Canada.

Snowpack Summary

Moderate south west winds continue to load lee slopes at tree line and above. The Dec. 11th persistent weak layer has been buried by up to 100cm snow and producing a significant natural cycle up to size 4, observable from the Icefields Parkway . The deep persistent weakness lingers near the ground.

Avalanche Summary

Friday's avalanche control produced consistent size 2 to 2.5 avalanches running to roadside. Damage from the most recent, intensive natural cycle is only now visible; with large slides, on skied terrain. Most notably is a large, possibly cornice triggered size 3.5, which ran nearly full run-out, on the Churchill (north and south) slide paths.

Confidence

Due to the number and quality of field observations

Problems

Wind Slabs

Moderate SW winds and new snow continues to build fresh wind, particularly near ridge-tops.

The new snow will require several days to settle and stabilize.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Persistent Slabs

This layer now sits under a meter of snow, any terrain that has not had previous activity on this layer should be given a wide berth.

Minimize overhead exposure during periods of heavy loading from new snow, wind.Watch for signs of instability such as whumpfing, or cracking.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3.5

Deep Persistent Slabs

Several recent large avalanches have been the result of the entire snowpack failing on or near the ground due to the weak snowpack structure surrounding this interface.

Be aware of thin areas that may propogate to deeper instabilites.Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 4

Valid until: Dec 23rd, 2018 4:00PM