Avalanche Forecast

Issued: Apr 2nd, 2012 10:32AM

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

jlammers, Avalanche Canada

Sea To Sky.

Summary

Confidence

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

Weather Forecast

The big story for the forecast period is an intense frontal system lined-up to hit the South Coast on Monday night. WInds will be in the strong to extreme range with heavy snow accumulations. Tuesday: moderate snowfall tapering off around mid-day - moderate to strong southwest winds decreasing throughout the day - freezing level at 1100m Wednesday: very light snowfall - light southwest winds - freezing levels at 900m Thursday: Mix of sun and cloud as a clearing trend develops - light north winds - freezing level at 1100m

Avalanche Summary

On Sunday, ski cutting and explosives control produced numerous size 1-1.5 windslab avalanches that ran within snow that fell over the previous 24hrs. Expect widespread wind and storm slab avalanche activity with potential to step down to the deeper March 26 interface with weather forecast for Monday night.

Snowpack Summary

Light to moderate new snow accumulations have added to the 75-100cm that fell last week. Winds have mostly been moderate with strong gusts creating wind slabs on lee slopes. The past week's snow overlies reactive surfaces that were buried on March 26. This interface consists of a crust which exists on all aspects except true north facing slopes at treeline and in the alpine, where small surface hoar may be present in sheltered places. Below the March 26 interface, the snowpack is well settled and bonded. Cornices are huge, and will continue to grow with the forecast weather pattern.

Problems

Wind Slabs

Forecast strong to extreme winds and heavy snowfall will form reactive and potentially destructive new wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 5

Storm Slabs

Forecast heavy snowfall will add to an ongoing storm slab problem. Storm slabs will be more destructive than usual if they fail on weak layers buried on March 26th.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 6

Cornices

Cornices are very large, potentially unstable and will continue to grow with forecast weather.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 6

Valid until: Apr 3rd, 2012 9:00AM