Avalanche Forecast

Issued: Dec 22nd, 2016 4:00PM

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

rupert wedgwood, Parks Canada

Jasper.

Look for stashes of fresh snow in low angled sheltered glades below tall timbered.

Summary

Weather Forecast

A weakening moist westerly flow will be replaced by an easterly arctic front overnight. During the next 36 hours winds will continue to decrease and shift to the north as temperatures fall; the arctic air returns. No significant snowfall is forecast and perhaps some sun for the weekend.

Snowpack Summary

10 cm of fresh snow may be found in low angle sheltered slopes. Wind slabs in lee areas and cross loaded gullies continue to grow as do the cornices overhead. Weak layers include; buried surface hoar (Dec 11) in sheltered NE aspects around treeline (2100-2300m) and the Nov 12 crust buried in places 1m below the surface and 20cm 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 larger fast running slab avalanches.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Friday

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.

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

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

Elevations: All elevations.

Likelihood

Likely

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 with this new loading pattern.

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

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 3

Valid until: Dec 23rd, 2016 4:00PM