Avalanche Forecast

Issued: Mar 19th, 2014 9:23AM

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

bcorrigan, Avalanche Canada

South Coast.

The hazard may be higher than expected on solar aspects if the sun comes out and the temperature goes higher than forecast. Pay careful attention to cornice hazard.

Summary

Confidence

Fair - Freezing levels are uncertain

Weather Forecast

Synopsis: A low pressure system over northwest BC will track south eastward through BC and into Alberta.Tonight: Cloudy with flurries, possible 5 to10 cm of precipitation, freezing level around 300 metres, winds from the west, light occasionally moderate.Thursday: Cloudy with sunny periods and possible flurries, trace of precipitation, freezing level around 700 metres, winds light to moderate, from the west.Friday: Cloudy with flurries, trace of precipitation, freezing level around 900 metres, light ridge top winds from the south.Saturday: Cloudy with flurries, trace of precipitation, freezing level around 1200 metres, ridge top winds, light from the south west.

Avalanche Summary

No reports of avalanches from yesterday in the forecast region. Conditions seem to be improving, but the Coquihalla area has recently experienced a large natural avalanche cycle and it may be too early to be stepping out to bigger objectives.

Snowpack Summary

Between 50 and 70 cm of recent storm snowstorm snow at upper elevations is sitting on a a variety of weak layers. Strong westerly winds continue to form wind slabs on lee slopes. The two persistent weak layers that remain a concern are:The March weak layer. A combination of hard wind-scoured slab surfaces in exposed terrain, facets and/or surface hoar in sheltered and north aspects, and sun crust on steep solar aspects and is generally widespread throughout the forecast region.A late January/early February crust/facet/surface hoar combo that is still showing up in snowpack tests with hard shear tests. This layer will be with us for a long time, and a slide triggered on this layer would be very large and destructive. Recent warming temperatures will be good for bonding on this layer, but a sudden increase in load, a cornice failure, or a big rain event could "wake up" this layer and result in large avalanches. There are also basal facets at the bottom of the snowpack from cold clear weather in early December, but for the most part these have not been a concern, however, recently, large avalanches have scoured some avalanche tracks down to the basal facets and even to the ground.

Problems

Storm Slabs

The last storm left us with wind slabs at tree line and above. Cornices are getting large and mature. Steep solar aspects may become active when the sun comes out on the recent storm snow.A cornice failure could produce a large and avalanche.

Be cautious as you transition into wind affected terrain.>Pay attention to overhead hazards like cornices.>Be careful with wind loaded pockets while approaching and climbing ice routes.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 4

Deep Persistent Slabs

The persistent weak layers buried deep in the snowpack have recently become reactive with new snow loading. Conservative terrain choices are important now.

Be aware of thin areas that may propogate to deeper instabilites.>Be aware of the potential for full depth avalanches due to deeply buried weak layers.>Give cornices a wide berth when travelling on or below ridges.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 20th, 2014 2:00PM