Avalanche Forecast

Issued: Apr 20th, 2017 8:00AM

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

percy woods, Parks Canada

Glacier.

Spring like conditions below treeline need to be factored into your exit plan from the alpine. Plan to be back to trailheads before the lower elevation snowpack becomes weakened by daytime warming.

Summary

Weather Forecast

Cloudy with isolated flurries, light west winds and an alpine temperature of -1C. Friday a mix of sun and cloud, light to moderate NW wind and an alpine temperature of 0C. Strong solar input is expected for Friday.

Snowpack Summary

No overnight freeze leaves below tree line lower elevations weak and isothermal. At higher elevations S through SW winds have redistributed Easter storm snow onto alpine lee features. Cornices are huge and ripe for failure. These large triggers may wake deep persistent weak layers resulting in large avalanches.

Avalanche Summary

Four new slides to size 2 in the highway corridor yesterday all out of solar aspects.

Confidence

Due to the number of field observations

Problems

Wind Slabs

Recent storm snow has been redistributed by moderate S-SW winds forming windslab in the immediate lee of ridges and crosswinded features. These slabs will be forming over sun crust on solar aspects and temperature crust on others.

Use caution in lee areas. Recent wind loading have created wind slabs.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Loose Wet

Limited overnight freeze and freezing levels rising to 1900m today will result in a weak wet snowpack below treeline. Expect surface sluffing this afternoon.

If triggered the loose wet sluffs may step down to deeper layers resulting in large avalanches.Use extra caution on slopes if the snow is moist or wet.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Cornices

Cornices are extra large. The potential for triggering increases with daytime warming and prolonged solar radiation.

Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.Pay attention to overhead hazards like cornices which could trigger slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Apr 21st, 2017 8:00AM