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Avalanche Forecast

Mar 29th, 2012–Mar 30th, 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
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
2: Moderate
The avalanche danger rating at treeline will be moderate
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
2: Moderate
The avalanche danger rating at treeline will be moderate
Below Treeline
2: Moderate
The avalanche danger rating below treeline will be moderate

Regions: Sea To Sky.

Confidence

Fair - Intensity of incoming weather is uncertain

Weather Forecast

Friday: Expect continued flurries with accumulations of 10cm possible. Winds ease to light southerlies with freezing levels climbing to 1400. Saturday: Morning convection should give way to a weak ridge giving sunny breaks through the afternoon. Winds should continue light southerly with freezing levels reaching 1200. Sunday: Another weak system could give light precipitation and slightly increased winds from the west.

Avalanche Summary

Many windslab events have been reported up to size 2.0. These have been triggered naturally, with explosives and with human traffic. Isolated windslab events have triggered remotely. Crown depths are a typically around 60cm and over 100cm in some locations. Isolated, small loose moist events are running below treeline.

Snowpack Summary

30-40cm of new snow fell in the past 24 hours bringing storm snow totals to between 70-90cm overlying the March 26 interface. This has been accompanied by consistently moderate and at times gusty southerly winds, forming deep windslabs in lee locations. Cornices are huge, and will continue to grow with this weather pattern. The 0326 interface is a crust on all aspects except true north treeline and alpine, where small surface hoar is present in sheltered places. In snowpack tests, the bond of the new snow and the March 26 interface is poor, with easy planar results. At lower elevations the high freezing level has kept the new snow heavy and moist. Below the newest storm interface, last week's storm snow is well settled and bonded, with further strength gains deeper in the pack. In isolated locations the weaknesses from early February linger and the chance for a large, deep release is possible in times of rapid loading from new snowfall, rain or cornice fall.

Avalanche Problems

Wind Slabs

Consistent moderate to strong winds have built windslabs in lee locations over the slick melt freeze crust and spotty surface hoar.

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 5

Cornices

Cornices are very large and may become more fragile with the increased load and wind.

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

Elevations: Alpine.

Likelihood: Possible - Likely

Expected Size: 2 - 6

Storm Slabs

The heavy, new snow is reactive in steep terrain at lower elevations

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 3