Avalanche Forecast

Issued: Feb 29th, 2016 4:00PM

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

garth lemke, Parks Canada

Jasper.

The persistent slab will be with us for sometime particularly with the buried Jan 28th surface hoar/facet layer down 50-80cm. Its sporadically distributed so difficult to predict.

Summary

Weather Forecast

Tuesday will be -12 to -4, flurries with 5cm of snow and Light S winds. Clouds, scattered flurries, freezing level around 1600m, and seasonal temperatures will be the rest of the week.

Snowpack Summary

Weak crust on S through W aspects. Dry, facetted and generally unsupportive facets below this crust. Wind slab on lee aspects from previous SW winds and persistent slab in open areas at tree line. Poor travel conditions below tree line due to weak facetted snowpack. The Jan 28 SH/FC layer down 80cm remains a concern but is sporadically distributed.

Avalanche Summary

On Sunday, a size 3 avalanche was triggered by a skier on a SW facing alpine slope at 2300m about 5km up Portal Creek off Pevril peak. The sliding layer was a 2cm thick layer of facets/decomposed surface hoar buried 80cm. It was 150m wide x 50cm deep (max 1.3m) x 600m long. Likely triggered in shallow spot and stepped down to ground a couple spots.

Confidence

Problems

Persistent Slabs

Persistent weak layers of decomposed surface hoar, facets, and depth hoar are in many locations. These layers have been stubborn to trigger underfoot but could be triggered by cornice failure or from shallow spot and release to ground.

Avoid steep slopes below cornices.Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Wind Slabs

Expect slab development immediate to lee ridge lines and cross loaded features. Bonding should be suspect, progress cautiously into steeper terrain.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Carefully evaluate terrain features by digging and testing on adjacent, safe slopes.

Aspects: North, North East, East, South East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 1st, 2016 4:00PM