Avalanche Forecast

Issued: Mar 20th, 2014 9:23AM

The alpine rating is considerable, the treeline rating is moderate, 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 - Timing or intensity of solar radiation is uncertain

Weather Forecast

Synopsis: Cool and unsettled conditions will prevail in the wake of a cold front that passed through the region last nightTonight: Cloudy, trace to 5 cm of precipitation, freezing level at valley bottom, winds light from the south west.Friday: Cloudy, trace of precipitation in the forecast, freezing level at valley bottom, light south ridge top winds.Saturday: Cloudy with snow, trace of precipitation, freezing level up to 1000 metres, ridge top winds, light to moderate from the south west.Sunday: Sunny with cloudy periods, No precipitation in the forecast, freezing level around 1300 metres, light ridge top winds from the south.

Avalanche Summary

No reports of avalanches from yesterday in the forecast region. Conditions seem to be improving, but both the Coquihalla and Joffre region area haveÂ recently experienced a large natural avalanche cycle. 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 within 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

Small, continuous amounts of storm snow have left us with wind slabs at tree line and above. Steep solar aspects may become active when the sun comes out on the recent storm snow. A cornice failure could produce a large destructive avalanche.

Pay attention to overhead hazards like cornices.>Be cautious as you transition into wind affected terrain.>Assess start zones carefully and use safe travel techniques.>

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.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 21st, 2014 2:00PM