Avalanche Forecast

Issued: Apr 2nd, 2015 8:37AM

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

pgoddard, Avalanche Canada

Cariboos.

The persistent slab problem is still on the radar, but shifting into a low-probability/ high-consequence situation. Be confident in your local snowpack before committing to any big terrain.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system is uncertain

Weather Forecast

Light snow starts on Friday night and continues through the weekend. (Estimates: 5-15 cm on Saturday; 5 cm on Sunday). Only light flurries are expected on Monday. The freezing level is around 1500 m by day, falling towards valley floor by night. Winds are generally light.

Avalanche Summary

On Wednesday, several size 2-3 slabs failed naturally. While the likelihood of triggering a large persistent slab avalanche is decreasing slowly, the consequences remain high.

Snowpack Summary

10-20 cm dry convective snow has been shifted by NW winds into wind slabs on lee slopes in the alpine. These overlie a recently formed crust which varies in thickness with elevation. Several persistent weak layers exist in the upper 1m of the snowpack and remain a concern. The mid-March crust/facet layer is down around 60 cm and has been reactive to light triggers recently. Down around 80-100 cm is the mid-February crust/facet/surface hoar layer which has also been reactive to heavy loads like avalanches in motion stepping down, cornice failures, or explosives. Both layers have the potential for wide propagations and very large avalanches are still possible.

Problems

Wind Slabs

Recent winds have shifted snow into wind slabs on lee and cross-loaded slopes. Cornices may be fragile.

Use ridges or ribs to avoid areas of wind loaded snow.>Be cautious as you transition into wind affected terrain.>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 - Likely

Expected Size

1 - 3

Persistent Slabs

Buried persistent weak layers may still be reactive to human-triggering and large avalanches remain possible. Smaller avalanches in motion or a cornice failure could step down to one of these deeper layers.

Caution around convexities or areas with a thin or variable snowpack.>Dig down to find and test weak layers before committing to a big line.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Valid until: Apr 3rd, 2015 2:00PM