Avalanche Forecast

Issued: Dec 2nd, 2017 3:55PM

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

mgrist, Avalanche Canada

Sea To Sky.

The lure of powder slopes and sunny skies will be strong on Sunday. Take a cautious approach towards more aggressive terrain - especially steep, wind-affected terrain.

Summary

Confidence

Moderate - Due to the number of field observations

Weather Forecast

We'll see a clearing trend on Sunday and fine weather during the week.Sunday: Clearing in the morning and then dry with some sunny breaks. Light northwesterly winds. Freezing levels 800m.Monday: Sunny with cloudy periods. Freezing levels around 600 m. Light northwesterly winds.Tuesday: Mainly sunny and becoming warm up high. Freezing levels rising to 2000 m. Light northerly winds.

Avalanche Summary

On Saturday, control work with explosives gave mostly Size 1 soft slabs. Over the past three days, ski cutting has consistently produced soft slab avalanches on lee and cross-loaded features, running to size 1.5 in the storm snow at treeline and alpine elevations. On Friday, most slabs triggered were approximately 25cm thick, running on a density change within the recent storm snow.

Snowpack Summary

Approximately 40-60 cm new snow now sits on top of a rain crust (or multiple crusts) that formed during the wet weather at the end of November. Strong (southerly) winds have blown snow around in exposed areas creating drifts and scoured areas. The main areas of concern are lee (northerly) and cross-loaded features in the alpine and treeline elevation bands. Snowpack depths are typically around 150 cm in sheltered treeline locations, although deeper (and shallower) spots certainly exist on account of the strong winds.

Problems

Wind Slabs

Wind slabs have been building over a crust layer. This layer may slide easily, particularly on steep convex terrain or where the wind has blown it into more cohesive slabs.

Use ridges or ribs to avoid pockets of wind loaded snow.Avoid steep lee and cross-loaded featuresBe alert to changing snow conditions, especially where the snow firms up or sounds hollow.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Dec 3rd, 2017 2:00PM