Avalanche Forecast

Issued: Apr 4th, 2015 8:27AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Loose Wet, Wind Slabs and Persistent Slabs.

pgoddard, Avalanche Canada

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.

Summary

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.

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

Valid until: Apr 5th, 2015 2:00PM