Avalanche Forecast

Issued: Feb 23rd, 2016 7:29AM

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

bcorrigan, Avalanche Canada

Kootenay Boundary.

Cautious terrain selection is critical these days. Pay attention to daytime heating on solar aspects and avoid cornice features.

Summary

Confidence

Moderate - Freezing levels are uncertain

Weather Forecast

A ridge of high pressure has moved in over province. We should see mostly sunny skies with a few clouds and the possibility of morning valley fog in some areas. Freezing levels are forecast to rise to 1500 metres during the day, but should drop to valley bottoms overnight. On Friday, freezing level may go to 3000 metres.

Avalanche Summary

Reports from yesterday tell us that wind slab avalanche activity is still not over. A widespread cycle of natural activity in the Bonnington range up to size 2.5 was also reported, and seems to have been the storm snow from the last wind and snow event. The February crust interface mentioned in the Snowpack Discussion section appears to be still active in some parts of the region, and is still something to be wary of. Warm temperatures and increased radiation on solar aspects makes for a good recipe for large avalanches.

Snowpack Summary

A considerable amount of snow fell during the past week, with the eastern part of the region receiving the most out of the storms. Moderate to strong south west winds have redistributed the surface snow into touchy wind slabs. A melt-freeze crust that formed during the 2nd week of February has been reported at various levels from 50 to 120cm throughout the region. This crust is widespread and may co-exist with surface hoar or weak facets, especially at treeline and below on north aspects. This reactive interface is a critical layer to watch in the region, and has been the active layer for some very large avalanches recently. Buried surface hoar layers exist in the drier areas on the west side of the region near Rossland and are worth keeping in mind. Surface hoar growing up to 6mm has been reported in the past 2 days throughout the region. Sun crust may exist on solar aspects at the surface and has also been reported in the region 20cm below the surface. Daytime heating will help settle the snowpack but could also make for touchy conditions on south facing slopes in the afternoon. Cornices can grow weak with daytime heating.

Problems

Wind Slabs

Use caution in terrain that was affected by wind during the last storm

Sluffs may trigger deeper instabilities.>Stay off recent wind loaded areas until the slope has had a chance to stabilize.>Avoid freshly wind loaded features.>Avoid all avalanche terrain.>

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

The storm slab should be bonding on north aspects, but may become reactive on solar facing slopes.

Use conservative route selection, stick to moderate angled terrain with low consequence.>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

2 - 5

Cornices

Cornices may become weak with daytime heating. Give them a wide berth.

Extra caution needed around cornices with current conditions.>Do not travel on slopes that are exposed to cornices overhead.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 4

Valid until: Feb 24th, 2016 2:00PM