Avalanche Forecast

Issued: Apr 8th, 2016 8:00AM

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

danyelle magnan, Parks Canada

Glacier.

Another warm night prevented an overnight recovery. Danger will rise quickly today as the sun hits the slopes. Temps will finally drop overnight and will help to form strong surface crusts. Plan to start and end your days early this weekend.

Summary

Weather Forecast

Today will be warm and sunny with freezing levels are expected to rise as high as 3600m, and alpine temps in the shade reaching 10'C. Overnight temps are expected to drop below freezing which will finally allow an overnight recovery and the beginning of a melt-freeze cycle. Sat and Sun should be mostly sunny with alpine temps reaching 4'C.

Snowpack Summary

At treeline and above a ~30cm storm slab overlies a crust. Below the crust the upper ~70cm of snow is warm, moist and weak. Sustained S'ly winds at ridgetop will have built deeper, more cohesive slabs on lee and cross-loaded slopes. At 1300m the surface crust that formed overnight is only 3cm thick with a very weak overnight recovery.

Avalanche Summary

Natural avalanches continue to occur daily with loose wet avalanches running to valley bottom. They have been occurring primarily from aspects where the start zones are in the sun. On Wed a skier triggered a size 2.5 on the headwall of Youngs Peak; a W aspect at ~2675m. The avalanche was 20-80cm deep and ran 150m. Luckily the skier was not buried.

Confidence

Problems

Loose Wet

We have yet to undergo a true melt-freeze cycle due to warm overnight temps and the snowpack is generally weak. It doesn't take long for the strong solar and very warm temps to break down the weak surface crust. Loose wet avalanches are expected.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.Avoid exposure to solar aspects overhead, large avalanches may reach the end of run out zones.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3

Storm Slabs

A ~30cm deep storm slab has developed and sits on a crust. Sustained winds will have built deeper pockets on lee slopes and in cross-loaded areas. These are likely to exist in areas where skiers/boarders are searching for skiable snow.

Be cautious as you transition into wind affected terrain.Use caution in lee areas in the alpine and treeline. Storm snow is forming touchy slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Cornices

Huge cornices along ridges will be weakened by the strong sun today and continued above freezing temps. A chunk of cornice tumbling down-slope is a concern in itself, but cornices failures also provide a heavy trigger and may trigger large avalanches

Give cornices a wide berth when travelling on or below ridges.Cornices become weak with daytime heating, so travel early on exposed slopes.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Apr 9th, 2016 8:00AM