Avalanche Forecast

Issued: Mar 30th, 2012 11:04AM

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.

mpeter, Avalanche Canada

South Coast.

If the sun pokes out and heats up solar aspects below treeline, danger will go up to CONSIDERABLE.

Summary

Confidence

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

Weather Forecast

Saturday: A system in Northern Washington may graze BC's South Coast, giving a chance of flurries and freezing levels rising to 1200m. Upper level southerly winds continue. Areas further east may see more clearing and higher freezing levels. 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 human triggered windslab events up to size 2.have been reported from lee and crossloaded features at treeline and above. Slabs are more reactive where the surface hoar is present, yielding wider propagation. We also have reports of isolated cornice releases in the high alpine to size 2.0 that did not release deeper layers. With persistent warm temperatures, there have been several large (3.0-3.5) natural glide crack releases in the Coquihalla area where the entire snowpack fails down to smooth rock slabs.

Snowpack Summary

30-50cm of new snow now overlies the March 26 interface. This has been accompanied by consistently moderate and at times gusty southerly winds forming windslabs in lee locations. Cornices are huge, and will continue to grow with this weather pattern. Settlement has been very The March 26 interface is a crust on all aspects except true north treeline and alpine, where small surface hoar (5mm) is present in sheltered places. The bonds between the new snow and this interface are weak, especially in locations where the surface hoar is present. Easy planar results have been observed in testing at treeline on surface hoar size 2-4mm. At lower elevations, the consistent high freezing levels have kept the new snow moist and heavy. The deep, persistent early February layers linger in the snowpack and remain a concern with heavy triggers and rapid loading.

Problems

Wind Slabs

New windslabs are forming with the new snow and increased wind. They are more reactive where they overlie small, preserved surface hoar.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Cornices

Large cornices loom at ridgecrest and will grow under the current conditions. They may act as a large trigger to deeper weaknesses.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 6

Storm Slabs

The new storm snow may become reactive if the sun comes out and heats up the slopes.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

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