Avalanche Canada mpeter, Avalanche Canada

Sea to Sky Avalanche Forecast

Mar 28th, 2012 11:19AM

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

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain

Weather Forecast

Expect precip to ramp up overnight and into Thursday morning, with as much as 25cm of new snow and strong southerly winds. The freezing level should fall overnight then reach a maximum of 1200m. Friday / Saturday: Precipitation should slow down with winds turning from southerly to westerly. Freezing levels will fall as the flow turns, bringing more seasonal temperatures.

Avalanche Summary

Small windslabs (to size2.0) are forming in lee locations, and are triggering naturally and with rider traffic with limited propogation.

Snowpack Summary

Above 1700m, 30-40cm of new snow now overlies the March 26 interface. This has been accompanied by consistently moderate and at times gusty southwesterly winds forming 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. At lower elevations, the surface snow has had less recovery and the upper snowpack is predominantly moist. Below the newest storm interface, last week's storm snow is well settled and bonded, with further strength gains deeper in the pack.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Very Likely - Likely

Expected Size

1 - 4
New windslabs are growing in lee locations over the slick melt freeze crust and spotty surface hoar. Some thin windslabs formed in unusual places from downflow winds on the weekend; these will now be disguised by the new snow.

Aspects:

North, North East, East, South East.

Elevations:

Alpine, Treeline.

Cornices

An icon showing Cornices

Likelihood

Likely - Possible

Expected Size

1 - 6
Cornices are very large and may become more fragile with the increased load and wind.

Aspects:

North, North East, East, South East.

Elevations:

Alpine.

Loose Wet

An icon showing Loose Wet

Likelihood

Likely - Possible

Expected Size

1 - 4
The heavy, new snow may sluff in steep terrain at lower elevations

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Valid until: Mar 29th, 2012 9:00AM