Archived

Avalanche Forecast

Feb 27th, 2012–Feb 28th, 2012

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

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

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Kananaskis.

Don't let the sunny skies lure you into more serious terrain. Surface hoar now buried 40 to 80cm remains highly reactive and caused cracking, whumpfing and remote triggered avalanches today. This problem will persist for some time. Be conservative.

Confidence

Good

Weather Forecast

Ridge of high pressure to dominate again on Tuesday with sunny skies. Winds moderate SW.

Avalanche Summary

Evidence of widespread Na and Nc cycle in past 12 to 48 hours up to size 2.5 on all asp and all elevations, with one size 3.0 observed on SE asp in ALP. All slides appeared to fail on 120213 SH or SC. Observed two Na on Commonwealth ridge, E asp, size 2.0 with tracks visible in on of the slides. Sev Sr(20m) in Burstall Pass from moderate terrain failing down 50 to 70cm on SH. One size 1.0 solar triggered slide, SW asp, 1700m on Mt Rundle.

Snowpack Summary

Average of 5cm Hn at TL. Extensive wind affect in ALP with large cornice growth and isolated wind affect at TL. Widespread whumpfing, cracking and Sr in moderate terrain at TL. Profile at 2300m, Hs = 200cm, CTM(12)(SC) down 50cm on 120213 SH, P density midpack overlies P- density basal FC/DH. Isolated solar affect os steep SW asp BTL only.

Avalanche Problems

Persistent Slabs

The Valentine's surface hoar and sun crust continue to be problems with extensive avalanche activity in the past 48 hours. The surface hoar is particularly touchy and is buried 40 to 80cm. Remote triggering, cracking and whumpfing occurred today.

Aspects: All aspects.

Elevations: All elevations.

Likelihood: Likely - Very Likely

Expected Size: 1 - 6

Wind Slabs

Widespread wind slab formation has occurred in the alpine on lee and cross loaded features. It is likely that a failure in these wind slabs will step down and trigger the buried surface hoar or sun crust.

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

Elevations: Alpine.

Likelihood: Likely

Expected Size: 1 - 6

Cornices

Cornices have grown significantly in the alpine. 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 ridgcrests.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 2 - 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. This problem is still a low probability issue, but with high potential consequences.

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

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 6