Avalanche Forecast

Issued: Mar 7th, 2012 8:22AM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

Avalanche control produced several large results with slides reaching the end of their runouts. Solar triggering will likely be a concern on Thursday. Extreme westerly winds expected. Very conservative terrain selection is strongly recommended.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Clearing trend Thursday with freezing levels climbing to at least 1500m. Strong to extreme west winds expected. A weak wave of precipitation arriving on Friday.

Avalanche Summary

Observations were limited in the main forecast zone, but avalanche control on EEOR and the Big Sister produced results up to size 3.0 with many slides running full path with deep deposits.

Snowpack Summary

Trace amount of Hn. Valentines layers buried 150cm on average at treeline. Significant wind transport at ridgetop today.

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

Likely - Very Likely

Expected Size

1 - 7

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 up to 150cm at treeline and above. Remote triggering, cracking and whumpfing continue to occur.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 7

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 - 7

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 8th, 2012 8:00AM