Avalanche Forecast

Issued: Jan 19th, 2014 8:36AM

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 Cornices.

bcorrigan, Avalanche Canada

South Rockies.

Summary

Confidence

Fair - Due to the quality of field observations on Wednesday

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 to moderate from the Southwest, freezing level in the alpine to 1400.Tuesday: Nil precipitation. Winds light from the Southwest, freezing level in the alpine to 1400.Wednesday: Nil precipitation. Winds light to moderate from the Southwest, freezing level in the alpine to 1400. Wednesday:

Avalanche Summary

Report of a size 2.5 snowmobile triggered avalanche in steep shallow snowpack, failing to ground level. Areas of shallow snowpack are of special concern, as well as areas where there is a hazard from above such as cornices or steep south facing cliffs.

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 may have been the failure plane for recent large natural avalanches. Forecast very warm temperatures may result in loose wet avalanches or cornice falls that could trigger the persistent weak layer at the base of the snow pack ( depth hoar ) or the surface hoar layer from late in November. Strong solar radiation combined with above freezing temperatures in the alpine could create very touchy triggering on Southerly aspects.

Problems

Wind Slabs

Strong winds have created hard wind slabs in the alpine and at tree line, very warm temperatures and strong solar radiation may increase the likelihood of triggering. A cornice failure or radiation sloughing in cliffs may trigger lower slopes.

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 - 4

Persistent Slabs

Recent 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 - 6

Cornices

Cornices may become weak and fail naturally with the strong solar radiation and warm alpine temperatures. Cornice falls are a large load that may release buried persistent weak layers on slopes below, resulting in very large 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 20th, 2014 2:00PM