Avalanche Forecast

Issued: Mar 30th, 2012 11:03AM

The alpine rating is considerable, the treeline rating is considerable, and the below treeline rating is moderate. Known problems include Wind Slabs, Cornices and Storm Slabs.

Avalanche Canada mpeter, Avalanche Canada

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather is uncertain

Weather Forecast

Saturday: A system to the South may graze the Sea to Sky, giving a chance of flurries and freezing levels rising to 1400m. Upper level southerly winds continue. Sunday / Monday: Expect continued unsettled conditions with precipitation building to heavy Monday afternoon. Freezing levels may reach 1200m each afternoon. Winds slowly turn southerly to southeasterly and increase as the precip intensifies.

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

The latest pulse of precipitation brings the storm snow totals to between 75-100cm 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. Settlement rate is dramatic with the persistent warm temps. 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. 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.

Problems

Wind Slabs

An icon showing Wind Slabs
Consistent moderate to strong winds have built hard windslabs in the alpine/upper treeline and soft slabs below. These overlie 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

An icon showing 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

An icon showing Storm Slabs
The new snow is reactive in steep terrain at lower elevations where the March 26 melt freeze crust is thicker.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Mar 31st, 2012 9:00AM