Archived

Avalanche Forecast

Apr 15th, 2015–Apr 16th, 2015

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Alpine

3: Considerable

The avalanche danger rating in the alpine will be considerable

Treeline

3: Considerable

The avalanche danger rating at treeline will be considerable

Below Treeline

2: Moderate

The avalanche danger rating below treeline will be moderate

Regions: Glacier.

Strong sun on new snow will make conditions touchy today, with solar triggered avalanches and cornice failures expected. Below treeline we are beginning to see a melt-freeze cycle, use caution when the crust is breaking down.

Weather Forecast

Expect mostly dry and clear weather until Friday. Today strong solar with light west winds and an alpine high of -1'C will destabilize the recent storm snow. Thurs will be similar but warmer with freezing levels rising to 2100m, a high 2'C and temps will stay warm overnight. Fri will be increasingly cloudy with showers and freezing levels to 2400m.

Snowpack Summary

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. Wind effected snow at treeline and above. Above 1700m the top 40-50cm is dry with moist or wet snow below it with multiple crusts in the top 1.5m of the snowpack. Sustained warm temps will rapidly weaken the snowpack.

Avalanche Summary

2 size 2 naturals were observed along the highway yesterday, 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 were reports of cornices triggering slabs, and skier remote's and accidentals to size 2.

Confidence

Timing or intensity of solar radiation is uncertain

Avalanche 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.

Choose well supported terrain without convexities.Be careful with wind loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 3

Loose Wet

The new snow will get a strong dose of sun today and loose avalanches are expected. Once moving, avalanches may dig down into wet snow deeper in the snowpack resulting in large wet avalanches.

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

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

Elevations: All elevations.

Likelihood: 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 - Likely

Expected Size: 2 - 4