Avalanche Forecast

Issued: Dec 23rd, 2018 4:26PM

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.

william lawson, Parks Canada

Jasper.

Over 100cm of snow has fallen in the Ice Fields region since Dec 11. This is the time to be on high alert when traveling in any avalanche terrain.

Summary

Weather Forecast

Little change expected in over the holidays, forecasted winds will tamper Sunday night as a SW flow will settle in for the next few days. Temperatures will remain cool with daytime alpine highs of -10°c. A detailed mountain weather forecast is available from Avalanche Canada.

Snowpack Summary

Moderate to strong south west winds continue to load lee slopes at tree line and above. The Dec. 11th persistent weak layer has been buried 50 to 100cm and is ripe for human triggering. The deep persistent weakness lingers near the ground.

Avalanche Summary

Recent avalanche control produced consistent size 2 to 2.5 avalanches running to roadside. Previous to the control work, a large natural avalanche cycle occurred primarily failing on the Dec 11 weak layer. 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

Problems

Wind Slabs

Moderate to strong south west winds have created firm windslabs in the alpine and exposed treeline slopes.

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

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.

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

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 4

Valid until: Dec 24th, 2018 4:00PM