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Avalanche Forecast

Apr 4th, 2015–Apr 5th, 2015
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
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

Regions: South Columbia.

Avoid exposing yourself to slopes that are getting affected by the springtime sun. The danger rating reflects conditions during the warm part of the day.

Confidence

Fair - Timing or intensity of solar radiation is uncertain on Sunday

Weather Forecast

Light snow fall is expected on Sunday, with sunny spells. This peters to flurries on Monday. On Tuesday, a ridge moves in, starting a few days of fine, sunny weather. The freezing level is around 1600 m by day, falling towards valley floor by night. Winds are generally light.

Avalanche Summary

On Friday, sun triggered a few size 2 avalanches in steep terrain. A skier was partially buried in a size 2.5 wind slab on a north aspect at 2600 m on Thursday. Some naturally-triggered wind slabs and cornice falls were also reported. On Wednesday, a naturally-triggered size 2.5 wind slab was observed on a NE aspect at 2500 m. An ice fall also triggered a size 3 deep persistent slab which failed at ground.

Snowpack Summary

Up to 20 cm dry snow may be hiding previously formed wind slabs on slopes lee to the NW. These overlie a crust which varies in thickness with elevation. Sun may destabilise new snow and cornices. Below about 2000 m, loose moist snow makes up much of the snowpack underneath a surface crust. Persistent weak layers in the upper snowpack remain a lingering concern. The mid-March crust/facet layer is down around 60 cm. Down around 80 cm is the mid-February crust/facet/surface hoar layer. Both of these layers are slowly improving in strength, although it may still be possible to trigger one of these, causing a very large avalanche.

Avalanche Problems

Loose Wet

Sun. Spring. New snow. The kiss of the sun is likely to spark a round of avalanche activity.
Minimize exposure to sun exposed slopes when the solar radiation is strong.>

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

Elevations: Alpine, Treeline.

Likelihood: Likely

Expected Size: 1 - 3

Wind Slabs

Wind slabs may be found behind terrain breaks like ridges and ribs. Large cornices may be fragile - give these a respectful berth.
Use ridges or ribs to avoid pockets of wind loaded snow.>Give cornices a wide berth when travelling on or below ridges.>

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

Elevations: Alpine, Treeline.

Likelihood: Possible

Expected Size: 1 - 4

Persistent Slabs

Buried persistent weak layers may still be reactive to human-triggering. Most likely triggers include a person or machine on a thin snowpack spot, or a cornice fall.
Dig down to find and test weak layers before committing to a big line.>Caution around convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood: Unlikely - Possible

Expected Size: 3 - 6