Avalanche Forecast

Issued: Mar 15th, 2014 9:29AM

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

rbuhler, Avalanche Canada

Northwest Coastal.

Summary

Confidence

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

Weather Forecast

The storm is expected to end on Sunday night. A break between storms is expected for most of Monday before the next system arrives Monday evening. The north of the region can expect less snowfall amounts than the south.Sat. Night/Sunday: Snowfall 20-40cm, freezing level am: 800m pm: 500m, ridgetop winds 30-50 km/h S-SW easing during the day.Monday: Cloudy with sunny breaks, mostly dry during the day, freezing level am: 300m pm: 600m, ridgetop winds 20-40 km/h W-NWMon. Night/Tuesday: Snow 15-25cm, freezing level am: 500m pm: 1000m, ridgetop winds 30-50 km/h SW

Avalanche Summary

Observations during the storm are limited but we have received reports of wind slab activity and explosive triggered slabs releasing on the early-March layer. Widespread natural activity is expected for Saturday night and Sunday.

Snowpack Summary

Storm slabs continue to build. S-SW winds are building wind slabs in leeward features. A widespread crust is expected below the storm snow at lower elevations.Before the weekend storm, the early March persistent weak layer was down up to 1m in the north of the region. The south of the region had less snowfall and the slab was down roughly 60cm. This weak layer consists of any of the following: hard wind slabs or wind-scoured slopes in exposed terrain, a thick layer of faceted snow on sheltered/shady slopes, isolated surface hoar on sheltered/shady slopes, and sun crust on steep solar aspects. The early-February weak layer of surface hoar or a crust/facet combo is typically buried over 1.5m deep. This layer continues to react in snowpack tests, primarily on sheltered north aspects around treeline. The weight of the new snow and rain has the potential to reactivate this layer resulting in large, destructive avalanches. Basal facets and/or depth hoar remain an isolated concern in shallow snowpack areas in the northern part of the region.

Problems

Storm Slabs

Heavy snowfall and strong winds continue to build new storm slabs. Expect stiffer wind slabs in leeward features from strong S-SW wind.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 3

Persistent Slabs

The early-March weak layer remains very active and there has been a lot of recent activity on this layer. Expect much of the new storm activity to release on this layer.

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 - 5

Deep Persistent Slabs

The deep February persistent weak layer has been quiet recently but may reactivate with the weight of the new storm snow. Smaller avalanches have the potential to step down to this deep layer resulting in very large, destructive avalanches.

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

3 - 7

Valid until: Mar 16th, 2014 2:00PM