Avalanche Forecast

Issued: Mar 22nd, 2014 9:20AM

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

bcorrigan, Avalanche Canada

South Coast.

Hazards may be higher than forecast on solar aspects in the afternoon. Pay close attention to danger from cornices.

Summary

Confidence

Fair - Timing or intensity of solar radiation is uncertain

Weather Forecast

Synopsis: An arctic high pressure ridge in the interior of BC will cool things down before the next Pacific frontal wave arrives on Monday..Tonight: Cloudy with a trace of precipitation, freezing level around 200 metres, winds light, from the north west.Sunday: Sunny with some cloudy periods, no precipitation in the forecast, freezing level around 400 metres, light ridge top winds from the north west.Monday: Cloudy with flurries, freezing level around 400 metres, winds light to moderate from the north.Tuesday: Cloudy with snow, 10 to 15 cm in the forecast, freezing level at 400 metres, winds light, south west.

Avalanche Summary

No reports of avalanche activity from yesterday. Steep south aspects may be of concern in the afternoon. Conditions seem to be improving, but It may be too early to be stepping up to bigger objectives.

Snowpack Summary

Between 35and 60 cm of 7-day storm snow has increased the slab sitting on the persistent weak layers. Wind slabs formed during the storms are reported to be bonding well to the storm slab. 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. This layer is now down between 70 and 80cm from the surface.A late January/early February crust/facet/surface hoar combo that is still showing up in snowpack tests with hard shear tests, now down 150 to 250cm from the surface. Recent warming temperatures will be good for bonding above and below 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, a few large avalanches have stepped down to the basal facets and the ground.

Problems

Storm Slabs

Continued small amounts of storm snow have produced 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 deep persistent layers seem to be dormant for the time being, but may be reactive with a large load, ( a cornice failure )or a rapid warming event.

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 23rd, 2014 2:00PM