Avalanche Forecast

Issued: Mar 22nd, 2014 9:25AM

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

bcorrigan, Avalanche Canada

Northwest Coastal.

Hazard could be higher than forecast on solar aspects in the afternoon. Cornices are growing large, mature and require careful consideration.

Summary

Confidence

Fair - Timing, track, or intensity of incoming weather system 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

Reports of avalanche activity appears dropped of yesterday, but the weak layers are still there. Any rapid change, ....loading, too much sun, or just a rapid temperature increase may bring back the beast. Rider triggering is still possible. Cornices have become quite large in some parts of the forecast region and they are definitely something to watch out for.

Snowpack Summary

The area has received 75 to 150cm of snow over the past 5 to 7 days. The recent storm snow arrived with strong winds and produced wind slabs at tree line and above, increasing the depth of the slab that now overlies the March persistent weak layer. In addition, much of the recent storm snow has fallen on a melt freeze and/or rain crusts that exist in most parts of the region below 1200 metres. This will most likely become reactive on solar aspects when the sun finally comes out.The March weak layer is 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 widespread throughout the forecast region. This layer is now buried close to 150cm in most parts of the region. A late January/early February crust/facet/surface hoar combo is still showing up in snowpack tests with moderate to hard shear tests. Recent warming temperatures will be good for bonding around this layer, but a sudden increase in load, cornice failure, or a large rainfall event could "wake up" this layer and result in a large destructive avalanche.

Problems

Storm Slabs

Considerable amounts of new snow has been redistributed onto lee slopes. This recent storm snow is sitting on a variety of older weak surfaces. Conservative terrain choices are critical right now. Rider triggered avalanches are definitely possible.

Use conservative route selection, stick to moderate angled terrain with low consequence.>Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

2 - 4

Persistent Slabs

Activity on the March and February weak layers has slowed down, but these layers are still subject to triggering with the right load, and would produce a very large destructive avalanche

Avoid runouts where triggering slopes from below is possible.>Avoid areas with overhead hazard.>Assess start zones carefully and use safe travel techniques.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 5

Deep Persistent Slabs

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Be aware of the potential for large, deep avalanches due to the presence of buried weak layers.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 23rd, 2014 2:00PM