Avalanche Forecast

Issued: Jan 21st, 2014 8:27AM

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

bcorrigan, Avalanche Canada

South Rockies.

Summary

Confidence

Good - Due to the quality of field observations

Weather Forecast

An upper trough will attempt to penetrate the upper ridge today over the province. Protions of it will ride southward through the province late on Wednesday bringing light to precipitation to south central BC. The ridge will rebuild for Thursday and Friday with temperature inversions and light winds.Wed: Flurries, with a trace of precipitation, light winds, freezing level to 1600M.Thursday: Nil Precip., light ridgetop winds, freezing level to 1600m.Friday: Nil precip., sun and clouds, ridge top winds light , freezing levels rise to 2300m.

Avalanche Summary

No reports of recent avalanche activity. Areas of shallow snowpack are of special concern right now, as well as areas where there is a hazard from above such as cornices or steep south facing cliffs. High temperatures at upper elevations may increase the chance of triggering from surface sloughing or cornice failure.

Snowpack Summary

Extensive wind transport and wind slab development has occurred in all areas of the region. Recent storm snow varies from 40-70 cm across the region and in some alpine areas storm slabs are more than a metre thick. Persistent weak layers of buried crusts/facets/surface hoar continue to be a concern, and are suspected to have been the failure plane for recent large natural avalanches. Surface facetting and surface hoar growth throughout the forecast region on northerly and protected aspects. Strong solar radiation and above-freezing temperatures producing sun crust on solar aspects.

Problems

Wind Slabs

Surface hoar and near-surface facetting from cold temperatures are beginning to erode the wind slabs. In some areas, however, winds are continuing to build wind slabs. Be extra cautious in areas of shallow snow pack with wind slabs on top.

Watch for areas of hard wind slab in steep alpine features.>Be careful with wind loaded pockets, especially near ridge crests and roll-overs.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Persistent Slabs

Storm snow and hard wind slabs have been added to the load above buried weak layers. Deeply buried weak layers may become harder to trigger, but the consequences could be very large destructive avalanches.

Be aware of the potential for large, deep avalanches due to the presence of buried facet/crust layer and depth hoar layer.>Make observations and assess conditions continually as you travel.>Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 5

Cornices

Cornices may become weak and fail naturally with the strong solar radiation and warm alpine temperatures. Cornice falls are a large load that could trigger buried persistent weak layers on slopes below, resulting in large and destructive avalanches.

Cornices become weak with daytime heating, so travel early on exposed slopes.>Avoid steep slopes below cornices.>

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Jan 22nd, 2014 2:00PM