Avalanche Forecast

Issued: Mar 27th, 2014 9:07AM

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 Deep Persistent Slabs.

triley, Avalanche Canada

Northwest Inland.

Summary

Confidence

Fair - Wind effect is extremely variable

Weather Forecast

Overnight and Friday: Overcast and cool overnight with freezing levels dropping down to valley bottoms. Continued strong Easterly outflow winds during the day with freezing levels rising to 500 metres.Saturday: Cool and overcast with a chance of flurries and freezing levels rising to 700 metres. Outflow winds are expected to continue from the East.Sunday: Chance of broken skies and periods of sun with a weak Northwest flow. Freezing levels rising to about 600 metres.

Avalanche Summary

No new reports of avalanches.

Snowpack Summary

The recent storm snow (40-50 cm) has been transported into pockets of wind slab by moderate Southwest winds in the South of the region and by Easterly winds in the North of the region. The storm slab is sitting on the March persistent weak layer of crusts/facets/surface hoar that is widespread across the region. A late January/early February crust/facet/surface hoar combo is still showing up in snowpack tests with moderate to hard shear test results. This layer is expected to be with us for a long time, and a slide triggered on this layer could be very large and destructive.

Problems

Wind Slabs

Easterly winds have developed wind slabs on lee aspects. Some areas in the South of the region may have had periods of Southwest winds.

Travel on ridgetops to avoid wind slabs on slopes below.>Avoid freshly wind loaded features.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 4

Persistent Slabs

The recent storm snow may not be well bonded to the buried weak layer of crusts/facets/surface hoar that developed during early March. Forecast cool temperatures may help to preserve this weak layer.

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Deep Persistent Slabs

The deeply buried persistent weak layer from early February continues to be a concern. Heavy loads like cornice falls or storm slab avalanches in motion may trigger this weak layer resulting in very large and destructive avalanches.

Pay attention to overhead hazards like cornices.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

4 - 7

Valid until: Mar 28th, 2014 2:00PM