Archived

Avalanche Forecast

Apr 15th, 2019–Apr 16th, 2019

Alpine

2: Moderate

The avalanche danger rating in the alpine will be moderate

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

2: Moderate

The avalanche danger rating in the alpine will be moderate

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

2: Moderate

The avalanche danger rating at treeline will be moderate

Below Treeline

1: Low

The avalanche danger rating below treeline will be low

Regions: South Columbia.

Be cautious of reactive deposits of fresh snow around ridges and in lee terrain. As the sun shines and the snowpack turns moist, the likelihood of triggering loose wet avalanches will increase, especially in areas with fresh snow.

Confidence

Moderate - Timing or intensity of solar radiation is uncertain

Weather Forecast

MONDAY NIGHT: Mostly clear / west wind, 10-15 km/h / alpine low -4 C / freezing level valley bottom TUESDAY: Cloudy with sunny periods and isolated flurries, trace accumulation / southwest wind, 20-40 km/h / alpine high 0 C / freezing level 2000 mWEDNESDAY: Mainly cloudy with isolated flurries, trace to 5 cm snow accumulation / southwest wind, 25-55 km/h / alpine high +1 C / freezing level 2100mTHURSDAY: Cloudy with wet flurries, 5-20 cm / southwest wind, 20 gusting to 40 km/h / alpine high +3 C / freezing level 2500 m

Avalanche Summary

On Sunday, a skier triggered a size 1.5 wind slab avalanche on a steep convex roll at 2150 m and explosives triggered a size 2 storm slab avalanche at 2350, both avalanches occurred on a northeast aspect. A natural avalanche Sunday was also observed north aspect at 2300 m. The size 2 storm slab avalanche failed on surface hoar likely buried early April. This isolated layer may see increased stress as winds redistribute snow and add load or temperatures penetrate the snowpack.Late Saturday, storm snow was sloughing in steep terrain with skier traffic and gaining cohesion.

Snowpack Summary

20-30 cm fell around the region since Saturday, south and westerly winds have produced isolated pockets of windslab around ridge crest and lee features. The new snow accumulated over a melt freeze crust on most aspects. On north-facing terrain above 2000 m, the new snow accumulated over another 20-30 cm wind-affected snow from early April, in isolated areas surface hoar may now be buried 50-65 cm. Older wind slabs sitting on surface hoar might still be sensitive to human triggers. Below treeline snow is disappearing rapidly. Sun and rising freezing levels are warming the snowpack and settling new snow, the likelihood of loose wet avalanches will increase as heat penetrates into the snowpack.

Avalanche Problems

Loose Wet

As the sun comes out and the snowpack warms and moistens, the likelihood of loose wet avalanches will increase.

Use extra caution on slopes if the snow is moist or wet.Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Minimize overhead exposure to cornices above.

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

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 1.5

Storm Slabs

Fresh snow and wind have produced more reactive deposits around ridge crest and in lee terrain. Older wind slabs may be hidden under new snow.

Be alert to conditions that change with elevation.Be careful with wind-loaded pockets, especially near ridge crests and roll-overs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Possible - Likely

Expected Size: 1 - 1.5