Avalanche Forecast

Issued: Dec 23rd, 2016 4:00PM

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

mark herbison, Parks Canada

Jasper.

Previous strong winds have formed reactive wind slabs which require careful evaluation and cautious route finding if you venture into higher elevations or open areas. Decent skiing can be found in low elevation sheltered areas.

Summary

Weather Forecast

Scattered flurries on Saturday as the arctic low moves over our region and dry cold air continues to filter southward. Up to 5cm of snow over night as the temps dip into the -20 range again for s short period of time, with light NE winds. Clearing skies and warmer temps for Christmas day.

Snowpack Summary

10 cm of fresh snow may be found in sheltered areas. Previous strong winds have built slabs in lee features, cross loaded gullies and added to the size of cornices. Weak layers include; buried surface hoar (Dec 11) in sheltered NE aspects around treeline (2100-2300m) and the Nov 12 crust approximately 30cm from the ground..

Avalanche Summary

No new reports or observations in the past 24 hours. The wind loading over the past 4 days has developed reactive slabs. Once triggered these may propagate widely and step down to the November rain crust producing large, fast running avalanches.

Confidence

Problems

Wind Slabs

Strong winds have created a mosaic of snow depths across the landscape. These slabs will vary greatly in their triggering sensitivity requiring each slope to be carefully evaluated. The only rule of thumb to keep in mind is caution is advised.

Be aware of the potential for wide propagations due to the presence of hard windslabs.Watch for whumpfing, hollow sounds, and shooting cracks.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Persistent Slabs

The depth of this crust is now highly variable, and may be as deep as 1m in lee areas that have received significant loading due to strong SW winds. Careful evaluation of this interface is essential.

Sheltered slopes at lower elevations will offer the best skiing.If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Dec 24th, 2016 4:00PM