Avalanche Forecast

Issued: Feb 6th, 2015 8:21AM

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

triley, Avalanche Canada

South Columbia.

The warm, wet, and windy storm continues to result in HIGH avalanche danger.

Summary

Confidence

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

Weather Forecast

Very strong Southwest winds and heavy precipitation is expected overnight and ending Saturday morning as the second of three pulses of moisture moves into the region. The Northeast of the region may remain cooler due to the influence of the arctic air to the North. Freezing levels should be between 1500 metres in the northeast and 2200 metres in the Southwest. Cloudy with strong Southerly winds during the day on Saturday with light to moderate precipitation, and then heavy precipitation starting in the late afternoon or evening. Winds dropping to moderate on Sunday combined with light precipitation and freezing levels slowly dropping. A weak Low pressure system is expected to bring moderate to heavy snowfall on Monday combined with moderate Southerly winds.

Avalanche Summary

Widespread natural avalanche activity up to size 2.0 was reported from the Selkirks and Monashees where slab avalanches released within the storm snow on Thursday. Observations were limited due to poor visibility and travel conditions on Friday

Snowpack Summary

The new snow has settled into a reactive soft slab that may release on the buried end of January crust, or on a weakness within the storm snow that is 10-15 cm above the crust. Widespread windslabs at ridgetops may be easy to trigger where they are sitting on the crust that formed last week. The new storm slab is up to 60 cm thick and sits above a variety of old surfaces. The old surfaces include the crust that formed last week, a new layer of surface hoar that developed during the clear weather late last week, and in some places wind slabs that developed smooth hard surfaces. Deeper in the snowpack the mid-January surface hoar remains a concern. It can be found down 60-120 cm across the region, but in most places it is about one metre down. In some locations it has reportedly gained quite a bit of strength, but elsewhere it is still producing sudden collapse (popping) failures in snowpack tests. The mid-December surface hoar layer is now 80 to 140cm below the surface and has become unlikely to fail, the storm at the end of the week should be a good test to see if it will become active again.

Problems

Storm Slabs

Strong winds, heavy snowfalls, and high freezing levels are expected to result in a widespread natural avalanche cycle within the storm snow or releasing on the late January buried crust.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Be cautious as you transition into wind affected terrain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

2 - 5

Persistent Slabs

Buried persistent weak layers may be over-loaded by the forecast new storm snow resulting in human triggering, or storm slab avalanches in motion stepping down to the deeply buried weak layers.

Be aware of thin areas that may propagate to deeper instabilities.>Choose well supported terrain without convexities.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 6

Wet Slabs

Continued rain at lower elevations may result in wet slab avalanches running to valley bottoms. Be aware of avalanche terrain that is above you when travelling on lower elevation access trails and roads.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 5

Valid until: Feb 7th, 2015 2:00PM