Avalanche Forecast

Issued: Mar 23rd, 2014 9:13AM

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

bcorrigan, Avalanche Canada

Northwest Inland.

The hazard may be higher than forecast on solar aspects in the afternoon. Pay attention to temperatures and possible cornice hazards.

Summary

Confidence

Fair - Forecast snowfall amounts are uncertain on Monday

Weather Forecast

Synopsis: The arctic high pressure ridge over the interior will keep things cool for the next few days.Tonight: Cloudy, no precipitation in the forecast, freezing level at valley bottom, winds moderate, from the south east.Monday: Cloudy with flurries, freezing level at valley bottom, winds light to moderate from the south east.Tuesday: Cloudy with snow,10 to 15 cm in the forecast, freezing level at valley bottom, winds light to moderate from the north.Wednesday: Sunny with come cloudy periods, no precipitation in the forecast, freezing level at valley bottom, ridge top winds light from the north.

Avalanche Summary

Reports of avalanche activity have dropped off, but the possibility is still out there. Cornice failures can produce large avalanches. With continued wind loading, rider triggering is definitely possible at this time.

Snowpack Summary

40 to 65 cm of precipitation 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 moist to ridgetops, and may have a crust with new snow on top of it. The solar aspects may become reactive when the sun comes out.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 would be very large and destructive. Recent warm temperatures are good for bonding around this layer, but a sudden increase in load, or a large rainfall event could "wake up" this layer and result in very large avalanches.

Problems

Storm Slabs

Storm snow and winds have left us with wind slabs at tree line and above, and growing cornices. Solar aspects may become active when the sun comes out on the recent storm snow. A cornice failure could produce a large destructive avalanche.

Avoid freshly wind loaded features.>Use conservative route selection, stick to moderate angled terrain with low consequence.>Cornices become weak with daytime heating. >

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 4

Persistent Slabs

There are persistent weak layers buried deep in the snowpack. Conservative terrain choices are important now.

Be aware of the potential for large, deep avalanches due to the presence of buried weak layers>Be aware of thin areas that may propogate to deeper instabilites.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Deep Persistent Slabs

These layers appear to be dormant right now, but could wake up with a large load.

Avoid exposure to overhead avalanche terrain, large avalanches may reach the end of run out zones.>Assess start zones carefully and use safe travel techniques.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

4 - 7

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