Avalanche Forecast

Issued: Dec 24th, 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.

Rupert Wedgwood, Parks Canada

Jasper.

Play safe and give yourselves lots of time to return home early for some Christmas cheer. Merry Christmas one and all. (TT)

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. Inversions can be expected with slightly warmer temps in the alpine.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 in the depth hoar and facets.

Avalanche Summary

Recent avalanche control (Dec 21) produced consistent size 2-2.5 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) paths.

Confidence

Due to the number of field observations

Problems

Wind Slabs

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

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

1.5 - 4

Valid until: Dec 25th, 2018 4:00PM