Avalanche Forecast

Issued: Feb 5th, 2016 7:58AM

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

jsmith, Avalanche Canada

Kootenay Boundary.

Extra Caution required in alpine and open treeline features.

Summary

Confidence

Moderate - Forecast snowfall amounts are uncertain

Weather Forecast

5-10cm of snow with moderate southwesterly winds on Friday night. No snow forecasted for rest of forecast period. Freezing levels rise sharply on Monday to 3000+m.

Avalanche Summary

Several skier triggered storm slab avalanches to size 2 were reported on Thursday. These were primarily triggered in lee features at treeline. One natural storm slab size 1.5 was observed on an east aspect at 2000m.

Snowpack Summary

5cm of new snow brings the storm slab to 35-45 cm and can be found across most of the region. This new snow lies above a variable old surface buried at the end of January. This interface is being reported as a layer of surface hoar at treeline in the Rossland area. However, in most other parts of the region the new snow sits on a rain crust and/or old wind slabs. A weak layer buried mid-January can be found down 45-50cm, however, snow pit tests indicate that this layer is gaining strength. Deeper in the snowpack, the persistent weak layer that was buried earlier in January is now down 80-120 cm and continues to give sudden planar fractures in snowpack tests under moderate to heavy loads.

Problems

Storm Slabs

Storm slabs may remain easy to trigger in alpine and open treeline.

Avoid exposure to terrain traps where the consequences of a small avalanche could be serious.>Choose well supported terrain without convexities.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

This persistent weak layer is a classic low probability but high consequence problem. Dig down to see if the surface hoar exists in your area.

Be aware of the potential for large avalanches due to the presence of buried surface hoar. >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 - 5

Valid until: Feb 6th, 2016 2:00PM