Avalanche Forecast

Issued: Mar 24th, 2014 9:30AM

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

triley, Avalanche Canada

Northwest Inland.

Forecast new snow and wind are expected to increase the avalanche danger.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Tuesday

Weather Forecast

Overnight and Tuesday: Some Pacific moisture (3-5 cm) is expected to push into the Northern coastal areas and then slide inland. Mostly overcast with light precipitation, cold alpine temperatures, and moderate to strong Southwest winds. Freezing levels at about 500 metres.Wednesday: Overcast with light precipitation and light winds. Freezing level about 500 metres and alpine temperatures around -15.Thursday: Overcast with a chance of sunny breaks in the afternoon. Light Easterly winds and temperatures around -15 in the alpine.

Avalanche Summary

No new reports of avalanches since the Silverking involvement on Saturday. The storm slab continues to be a concern for triggering from light additional loads. Long fracture propagations and triggering from adjacent terrain are likely.

Snowpack Summary

There has been 40 - 65 cm of new snow in the past week in parts of the forecast region. That, combined with strong winds, continues to build wind slabs in lee terrain and increase the depth of the storm slab that overlies the persistent weak layers. A rain crust has formed at lower elevations, typically below 1200 metres. Solar aspects have been reported to be moist to ridgetops, and may have a crust with new snow on top of it. The March weak layer is a combination of wind pressed snow, 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 well over a metre in some 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. This layer will be with us for a long time, and a slide triggered on this layer could be very large and destructive.

Problems

Storm Slabs

Forecast new snow and wind are expected to add to the load of the recent storm snow. Pockets of wind transported snow may develop at higher elevations.

Avoid freshly wind loaded features.>Minimize exposure during periods of heavy loading from new snow, wind.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 4

Persistent Slabs

The added load of new snow may result in increased sensitivity to triggering the persistent weak layer of crusts/facets/surface hoar.

Be aware of thin areas that may propogate to deeper instabilites.>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 - Likely

Expected Size

2 - 4

Deep Persistent Slabs

The deeply buried persistent weak layer from early February continues to be a concern. Heavy loads like cornice falls or storm slab avalanches in motion may trigger this weak layer resulting in very large and destructive avalanches.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Pay attention to overhead hazards like cornices.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

4 - 7

Valid until: Mar 25th, 2014 2:00PM