Avalanche Forecast

Issued: Mar 6th, 2012 8:49AM

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

mike.koppang, Alberta Parks

Kananaskis.

Clearing skies and avalanche control work at the end of the storm highlight some impressive avalanche events. Deep fracture lines, long run outs and widespread propagation within soft slabs in the alpine continue to highlight dangerous conditions/BD

Summary

Confidence

Good

Weather Forecast

Snowfall tapering off but NW winds increasing to EXTREME values over next 24 hours.

Avalanche Summary

Numerous natural soft slab avalanches to Size 3.5 over past 24 hours. Typical fracture lines are 75 to 150 cm deep. Avalanche control via helicopter bombing produced numerous Size 2-3 slides with wide propagation and long run outs up to 1000 meters. One natural Size 3 slide on Buller Mtn reached the road with deposits up to 1.5meters deep.

Snowpack Summary

22cm additional snowfall by Tuesday AM when the storm ended. Total snowfall over the past 36 hours is approx 60 in valley bottom with as much as one meter at treeline. Storm snow in wind loaded areas will easily exceed 1 meter depth.

Problems

Wind Slabs

Winds have formed hard and soft slabs at all elevations on lee and cross loaded features. A failure in these slabs will likely step down and trigger the surface hoar or the basal facets. Avalanches are occurring on this layer.

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

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 6

Persistent Slabs

The Valentine's surface hoar and sun crust continue to be a problem The surface hoar is particularly touchy and is now buried over 125 cm's at treeline and above. Remote triggering, cracking and whumpfing are occurring.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 6

Deep Persistent Slabs

Weak facets and depth hoar linger at the base of the snowpack. Thin steep areas are the most likely trigger points. Avalanches are stepping down to this weakness.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

3 - 6

Cornices

Cornices have grown significantly in the alpine. Failures continue to occur and have triggered avalanches up to size 3 on the underlying slopes. Give cornices a wide berth and stay well back from corniced ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 6

Valid until: Mar 7th, 2012 8:00AM