Avalanche Forecast

Issued: Mar 4th, 2012 8:41AM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

More than 30cm of new snow, warm temperatures and extreme westerly winds are forecasted. A significant avalanche cycle is expected. Avoid all avalanche terrain.

Summary

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Moderate to heavy snowfall with mild temperatures and strong to extreme W winds. Wind will shift to the N late Monday and precip will taper off.

Avalanche Summary

Visibility was very limited, but one size 2.0 Na slab on N asp at 2600m was observed at 10:30. It failed underneath a cornice, but the cornice was still intact, so suspect rapid wind loading was the trigger.

Snowpack Summary

5cm Hn with HST totals 10 to 15cm. 120213 SH now buried 40 to 80cm. HSL and SSL at ALP and TL and SSL forming in open areas BTL. Extensive cracking and whumpfing.

Problems

Persistent Slabs

The Valentine's surface hoar already buried up to 80cm will quickly become overloaded with the forecasted snowfall of 30cm and extreme W winds. Remote triggering is a real concern. Avoid wind loaded terrain at all elevations.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 7

Wind Slabs

Hard and soft slabs are present at all elevations on lee and cross loaded features. These slabs will continue to develop with the forecasted wind and snow. A failure in these slabs will likely step down and trigger the deeper weak layers.

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

Elevations: All elevations.

Likelihood

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. Snowboarders triggered a size 3.0 slide on Thursday on this layer when the initial wind slab stepped down to ground.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Cornices

Cornices have grown significantly at alpine and treeline elevations. Failures continue to occur and have triggered avalanches up to size 2.5 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 - Very Likely

Expected Size

2 - 6

Valid until: Mar 5th, 2012 8:00AM