Avalanche Forecast

Issued: Mar 8th, 2016 8:52AM

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.

triley, Avalanche Canada

South Columbia.

The persistent weak layer of buried surface hoar continues to allow for long fracture propagations and remote triggering.

Summary

Confidence

Moderate - Timing, track, or intensity of incoming weather system is uncertain on Thursday

Weather Forecast

Freezing down to valley bottoms overnight with light precipitation and moderate southwest winds. Mostly cloudy on Wednesday with moderate southerly winds and freezing level climbing to 1500 metres during the day. Strong southerly winds developing Wednesday night with moderate to heavy precipitation and freezing levels up to 1800 metres. Storm continuing on Thursday with moderate precipitation and freezing levels at 1800 metres. Mostly sunny on Friday with light winds and freezing levels remaining above 1500 metres.

Avalanche Summary

We have limited information about a single fatality avalanche incident in the Monashees south of Sicamous. It appears the avalanche occurred on Sunday and involved a snowmobiler riding alone, we will share more information when it becomes available. Skier accidental and natural avalanches up to size 1.0 were reported from the Monashees, and natural cornice falls and natural avalanches up to size 2.0 were reported from the Selkirks on Monday. On Sunday we received reports of natural storm slab avalanches up to size 2.0 in the Monashees and the Selkirks. Natural avalanches up to size 2.5 were reported on Saturday. Skier accidental, skier remote triggered, and natural avalanches up to size 2.5 continued to be reported on Friday. Most of these avalanches were releasing in the storm snow, or at the storm snow/surface hoar interface. North thru northeast aspects above 2100 metres are the most likely places for the persistent slab problem to exist.

Snowpack Summary

A surface crust has developed on all aspects up to at least 1700 metres. Some reports from the Monashees of a thin melt-freeze crust (March 5th) that has developed within the storm snow has been reactive up to size 2.0 on Sunday. Variable amounts of new snow and wind have continued to develop storm slabs 60-80 cm thick that are bonding poorly to a crust on previously sun-exposed slopes and surface hoar (February 27th) on shady and sheltered slopes. The surface hoar and/or crust layer buried February 10 is likely down over a metre. This layer has become less likely to trigger, but continues to be a concern for commercial operations.

Problems

Wind Slabs

Wind slabs may continue to be easy to trigger with light additional loads. Wind slab avalanches in motion may step down to the deeply buried persistent weak layer of surface hoar from February 27th.

Be cautious as you transition into wind affected terrain.>Be alert to conditions that change with elevation.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

The persistent weak layer of buried surface hoar may be most likely to trigger on north thru northeast aspects above 2100 metres. Remote triggering and long fracture propagations continue to be a concern.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Caution around convexities or areas with a thin or variable snowpack.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 5

Valid until: Mar 9th, 2016 2:00PM