Archived

Avalanche Forecast

Mar 4th, 2012–Mar 5th, 2012

Alpine

5: Extreme

The avalanche danger rating in the alpine will be extreme

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

4: High

The avalanche danger rating below treeline will be high

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

4: High

The avalanche danger rating at treeline will be high

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Alpine

4: High

The avalanche danger rating in the alpine will be high

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

3: Considerable

The avalanche danger rating below treeline will be considerable

Regions: 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.

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.

Avalanche 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