Avalanche Forecast

Issued: Mar 10th, 2017 4:00PM

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

garth lemke, Parks Canada

Jasper.

Winds are whipping up 45cm of low density snow into slabs. Assess each slope carefully.

Summary

Weather Forecast

Saturday into Sunday a.m. will be clouds, 5-10cm of snow, 25km/hr South to Southwest sinds, and -4 to -6 degrees Celsius. Winds speed increases slightly Sunday and Monday out of the W-SW with clouds and flurries. Temperatures will remain the same.

Snowpack Summary

SE Winds are creating windslabs 30-60cm thick. It rests on a persistent slab that has a cornucopia of wind and facet layers throughout the midpack. The lower snowpack is weak with depth hoar and a November rain crust. S aspect at Parker's there is a Surface hoar layer on a sun crust down 30cm testing unstable sudden planar fracture characteristic.

Avalanche Summary

Friday's field patrol into Portal creek from Marmot basin had no whumphing or shooting cracks. Thursday a cornice triggered a size 2.5 on Parkers Slabs. Churchill slide path on Thursday observed no whumphing or shooting cracks but the team stayed very conservative near the trees. Skiers on March 7 in Bald hills triggered a size 2 from a km away.

Confidence

Wind effect is extremely variable

Problems

Wind Slabs

SE winds are creating slab on lee aspects and firming it up on windward aspects. March 3rds 45cm of low density snow is available for transport. It may be overtop a decomposed SH layer on CR 30cm down on South TL aspects.

Make observations and assess conditions continually as you travel.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

Persistent mid-pack slab condition has been developing all season. Various wind and facet layers exist. Spatial variability exists with thick and thin snowpack areas.

Be wary of slopes that did not previously avalanche.Watch for whumpfing, hollow sounds, and shooting cracks.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 3

Deep Persistent Slabs

Natural activity has subsided but don't let your guard down. It remains a major concern with a extremely weak base of depth hoar. Trigger spots would be shallow zones or a step down effect if upper layers are initiated.

Avoid shallow snowpack areas where triggering is more likely.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Mar 11th, 2017 4:00PM