Avalanche Forecast
Issued: Mar 18th, 2012 4:00PM
The alpine rating is Wind Slabs, Deep Persistent Slabs and Cornices.
, the treeline rating is , and the below treeline rating is Known problems includeSummary
Confidence
Fair - Forecast snowfall amounts are uncertain
Weather Forecast
Monday: Unsettled conditions with flurries or periods of snow, and possible sunny breaks (2-5cm). The freezing level should be around 1000-1200m. Winds will be moderate and gusty from the SW. Tuesday: Light to moderate snow - 5-15cm. The freezing level is around 1000m during the day and valley bottom overnight. Winds are moderate to strong from the SW. Wednesday: Unsettled conditions with cloudy skies and light flurries. The freezing level is around 800-1000m. Winds ease to light from the SW.
Avalanche Summary
Recent avalanche activity includes one Size 2 accidentally triggered avalanche. It occurred in relatively well-supported treed terrain on a north aspect. The skier triggered the avalanche in a shallow rocky area. There was also a report of a Size 3.5 avalanche on Saturday that was remotely triggered by a snowcat. This occurred just north of the region in the southern Purcells. It highlights the potential for triggered very large and destructive avalanches. Other observations on Saturday include several loose snow avalanches up to Size 2 on all aspects and skier controlled or explosive controlled avalanches up to Size 2 with 10-150cm deep crowns.
Snowpack Summary
Rain fell to around 2000 m on Thursday afternoon and froze into a crust on all aspects below this elevation. 10-30cm of new snow now sits above the crust. The previous storm snow overlies a sun crust on southern aspects and maybe a spotty 2-6mm surface hoar on north and east aspects, down around 60cm. Below that, the more significant early February surface hoar is down 80-140cm. Snowpack tests show moderate to hard forces generating sudden planar shears on this layer. Below the early February surface hoar layer, the snowpack is strong in most places. Cornices are growing and would act as a significant trigger for all the layers mentioned above if they drop.
Problems
Wind Slabs
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Deep Persistent Slabs
Aspects: All aspects.
Elevations: All elevations.
Likelihood
Expected Size
Cornices
Aspects: North, North East, East, South East.
Elevations: Alpine, Treeline.
Likelihood
Expected Size
Valid until: Mar 19th, 2012 9:00AM