Avalanche Forecast

Issued: Apr 16th, 2015 8:05AM

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

Lydia Marmont, Parks Canada

Glacier.

Strong solar effect will weaken the snowpack at all elevations today. The buried surface hoar continues to be easily triggered by riders although there is little natural activity to indicate it's sensitivity.

Summary

Weather Forecast

Mostly sunny today with some convective cloud cover building around mid day. Freezing levels going to 2300m with alpine temps warming to 3 deg. Light flurries expected tomorrow before a warm ridge brings very warm air to the region Friday night and through the weekend

Snowpack Summary

Crust on solar aspectsfrom yesterdays warming will break down with forecasted temperatures. Up to 50cm of snow has settled into a slab sitting a crust on solar aspects and surface hoar on sheltered north and east aspects. Below 2200m a moist or wet layer that persists down 50cm will weaken rapidly with the forecasted warm temps.

Avalanche Summary

2 size 2 naturals were observed along the highway on Tuesday, triggered by windloading. On Sunday, skiers triggered slab avalanches to size 1.5 in the Tree Triangle gully at ~2000m, 30-40cm deep, 20m wide and 75m long. In the surrounding region there are reports of cornices triggering slabs, and skier remote's and accidentals to size 2.

Confidence

Intensity of incoming weather systems is uncertain on Saturday

Problems

Storm Slabs

40cm of recent snow has settled into a slab sitting on surface hoar on N'ly aspects and a sun crust on S aspects. Strong winds at ridgetop have created deeper pockets and loaded lee slopes. Today's strong sun will likely make it more reactive.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Loose Wet

The storm snow will get it's strongest sun so far today and loose avalanches are expected. Once moving, avalanches will likely dig down into wet snow deeper in the snowpack resulting in large wet avalanches.

Watch for clues, like sluffing off of cliffs, that the snowpack is warming up. Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.

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

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Cornices

New snow and strong winds at ridgetop have caused the existing cornices to grow even larger. Today they will be weakened by strong solar. Large cornice failures have been observed recently, sometimes triggering very large deep slab avalanches.

Cornices become weak with daytime heating, so travel early on exposed slopes.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

2 - 3

Valid until: Apr 17th, 2015 8:00AM