Avalanche Forecast

Issued: Mar 23rd, 2014 9:26AM

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, and scary-looking and require careful consideration.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Monday

Weather Forecast

Synopsis: The high pressure ridge in the interior of has cooled things down a bit, but will recede with the oncoming Pacific frontal system.Tonight: Cloudy, no precipitation in the forecast, freezing level around 100 metres, winds light to moderate, from the north west.Monday: Cloudy with flurries. Forecast models differ on precipitation amounts for Monday night freezing level around 400 metres, winds light to moderate from the north. .Tuesday: Cloudy with a trace of precipitation in the forecast, freezing level at 600 metres, winds light, from the north.Wednesday: Cloudy with isolated flurries, trace of precipitation in the forecast. freezing level around 600 metres, light ridge top winds.

Avalanche Summary

No reports of avalanche activity in the forecast region from yesterday. Remember that the weak layers are still there, and 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 and increasing the depth on 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. This layer is widespread throughout the forecast region and is now buried close to 150cm in most parts of the area. A late January/early February crust/facet/surface hoar combo is still showing up in snowpack tests with moderate to hard shear tests. It appears to be dormant for the time being, but a sudden increase in load, a cornice failure, or a large rainfall event could "wake up" this layer and result in a large destructive avalanche.

Problems

Storm Slabs

Considerable 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.

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

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 will produce a very large destructive avalanche

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

1 - 5

Deep Persistent Slabs

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 6

Valid until: Mar 24th, 2014 2:00PM