Avalanche Forecast

Issued: Dec 23rd, 2016 8:00AM

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

andrew jones, Parks Canada

Glacier.

Although stability is improving, the current avalanche hazard requires careful assessment and thoughtful decision making.

Summary

Weather Forecast

Cloudy with scattered flurries today accumulating to 5cm. Freezing levels rising to 700m with an alpine high of -9. Ridge winds will be southeast 25 km/h. Sun returns on the weekend with a ridge of high pressure but temperatures will remain cold. On monday a low pressure system with a SW flow brings more scatted precipitation and another 10cm.

Snowpack Summary

10cm of new snow fell overnight bringing the height of snow at treeline to 2m. Recent storm snow is settling into a persistent slab sitting on the December 18th facet/ surface hoar layer down55cm. Stability tests are showing that the Dec 18th interface is reactive. Buried wind slabs exist near ridges. The lower pack contains faceted weak layers.

Avalanche Summary

Hand charge testing produced 1 size 1 avalanche in a thin storm slab. Yesterday, a field team observed whumphing and cracking in the storm slab on approach to the Grizzly Shoulder head wall.

Confidence

Problems

Storm Slabs

Cold temperatures have kept recent storm snow light and powdery, but slab properties are beginning to form. The slab sits on the December 18 facet/ surface hoar down 50-60cm. Stability tests show that the storm slab is reactive to skier loads.

Dig down to find and test weak layers before committing to a line.New snow will require several days to settle and stabilize.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Wind Slabs

Strong SW winds during the last storm loaded lee slops and formed stiffer slabs. Wind slabs are poorly bonded to facetted snow below. A field team confirmed that these slabs were touchy around ridges and in areas of cornice growth.

Watch for signs of instability such as whumpfing, or cracking. Use caution in lee areas in the alpine and treeline. Recent storm snow has formed wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Dec 24th, 2016 8:00AM