Avalanche Forecast

Issued: Jan 18th, 2014 8:39AM

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.

Daytime heating and solar radiation will play a large role in the danger rating for the next few days.

Summary

Confidence

Good - Timing or intensity of solar radiation is uncertain

Weather Forecast

Overnight: Temperatures cooling down, nil precip., freezing level at valley bottom, light to moderate SW winds.Sunday: Sunny with some cloudy periods, nil precip., variable light winds. Freezing level around 1300m.Monday: Sunny with some cloudy periods, nil precip., light winds, freezing level to 1300m.Tuesday: Sunny with some cloudy periods, nil precip., light winds, freezing levels rise to around 1700m.

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

The storm slab in the North is close to a metre thick and appears to be more touchy than in most of the rest of the region. The Rossland area appears to have a shallower snowpack and weak basal facets continue to be a concern where wind slabs and storm slabs have added load above the weak layers. The forecast very warm alpine temperatures may result in periods of rapid warming of the wind and storm slabs above weak layers. Periods of strong solar radiation may cause moist or wet loose snow avalanches and/or cornice falls which could result in large additional loads above deeply buried weak layers. Surface hoar has been reported forming on protected north slopes along with facetting of surface HST and storm slab in protected locations.

Problems

Wind Slabs

Recent storm snow and strong wind has produced wind slabs 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 sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Be cautious as you transition into wind affected terrain.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>Avoid shallow snowpack areas where triggering is more likely.>

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.

Avoid sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar, facets/crust and depth hoar.>Avoid areas with overhead hazard.>

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 sun exposed slopes when the solar radiation is strong, especially if snow is moist or wet.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Avoid lingering in runout zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Jan 19th, 2014 2:00PM