Avalanche Forecast

Issued: Jan 19th, 2014 8:38AM

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

bcorrigan, Avalanche Canada

Kootenay Boundary.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Synopsis: A strong ridge of high pressure over BC and western Alberta is doing a good job of blocking Pacific moisture from the region. An inversion will see temperatures higher in the alpine than at treeline.Overnight: Nil precipitation. Winds light to moderate from the west, freezing level at valley bottom.Monday: Nil precipitation. Winds light at ridge tops, freezing level in the alpine to 1300m.Tuesday: Nil precipitation. Winds light at ridge tops, freezing level in the alpine to 1400m.Wednesday: Nil precipitation. Winds light at ridge tops, freezing level in the alpine to 1400m.

Avalanche Summary

Recent explosive controls reported results in storm snow only. Sluffing in steep terrain, snowballing and pinwheel activity on steep solar aspects.

Snowpack Summary

Wind continues to redistribute surface snow throughout the region. The snowpack varies widely, but appears to be deeper in the north and east. Basal facets continue to be a concern where wind slabs and storm slabs have added load above these weak layers. The forecast very warm alpine temperatures may result in periods of rapid warming of the wind and storm slabs above weak layers. Strong solar radiation may cause moist or wet loose snow avalanches or cornice falls in the alpine resulting in large additional loads above deeply buried weak layers. Surface hoar has been reported forming on protected north and east slopes along with facetting of the surface and storm slab in protected locations.

Problems

Wind Slabs

Wind slabs continue to grow at higher elevations. In some areas up to one metre thick. Warm alpine temperatures may result in loose wet avalanches on southerly aspects, or cornice falls, triggering deeper instabilities.

Avoid shallow snowpack areas where triggering is more likely.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 4

Persistent Slabs

Recent storm snow may not be bonding to the surface hoar and melt-freeze crusts that developed before the storm. Storm slabs are more likely in areas sheltered from the recent strong winds. Forecast warm temperatures may result in easier triggering.

Be aware of thin areas that may propogate to deeper instabilites.>Watch for whumpfing, hollow sounds, shooting cracks or recent avalanches.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 5

Deep Persistent Slabs

This problem is more likely in areas that had a shallow snowpack during the cold arctic outbreak. Loose wet avalanches or cornice falls may trigger deeply buried weak layers resulting in large destructive avalanches.

Avoid lingering in runout zones.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Jan 20th, 2014 2:00PM