Avalanche Forecast

Issued: Mar 12th, 2014 9:54AM

The alpine rating is high, the treeline rating is high, and the below treeline rating is considerable. Known problems include Storm 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

Thursday should be relatively dry before the next frontal system reaches the coast on Thursday evening. Precipitation is expected for Friday and Saturday. Heaviest amounts are expected for the south of the region.Thursday: Cloudy, dry conditions during the day, snowfall in the evening, freezing level am: 500m pm: 900m, ridgetop wind light S-SWThurs. Night/Friday:Snowfall10-25cm, freezing level am: 500m pm: 900m, ridgetop wind 30-50 km/h S-SWSaturday: Snowfall light to moderate, freezing level am: 500m pm: 1000m, ridgetop wind light to moderate S-SW

Avalanche Summary

Widespread natural avalanche activity is being reported on Tuesday and Wednesday.

Snowpack Summary

Storm slabs continue to build. In the north of the region, the storm slab is up to 1m thick. The south of the region had less snowfall and the slab is roughly 60cm thick. These slabs sit on a weak layer which may consist 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. Expect moist or wet snow below roughly 1000m elevation. The mid 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 at or below 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 a concern in shallow snowpack areas in the northern part of the region.

Problems

Storm Slabs

60-100cm of recent storm snow sits on a weak layer from early March. This layer is highly reactive due to continued loading from storm systems. Strong to extreme SW winds have formed wind slabs in lee and cross-loaded terrain features.

Avoid all avalanche terrain during periods of heavy loading from new snow, wind, or rain.>Be aware of the potential for wide propagations due to the presence of hard windslabs.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

2 - 5

Deep Persistent Slabs

The weak layer from early Feb is down roughly 1.5m and continues to be reactive in isolated areas. Heavy triggers such as storm avalanches or cornice falls have the potential to trigger this deep layer which would resulting in very large avalanches.

Be aware of the potential for large, deep avalanches due to the presence of buried surface hoar.>Be aware of thin areas that may propogate to deeper instabilites.>Avoid lingering in runout zones.>

Aspects: North, North East, East.

Elevations: All elevations.

Likelihood

Possible

Expected Size

3 - 7

Valid until: Mar 13th, 2014 2:00PM