Avalanche Forecast

Issued: Nov 26th, 2016 8:05AM

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

andrew jones, Parks Canada

Glacier.

Strong winds and new snow has increased avalanche hazard, especially above treeline. Avoid heavily loaded features and traveling near or below recently formed cornices.

Summary

Weather Forecast

We are mid-storm with an additional 8cm of accumulation expected today. Strong southerly winds with gusts to 70km/h and freezing levels rising to 1800m this afternoon. We return to a weak westerly flow later tonight with unsettled conditions and trace amounts of precipitation through to Tuesday. A high pressure ridge builds next week.

Snowpack Summary

Strong winds and new snow created a wind slab instability on lee features and in avalanche start zones. The Nov 23 temperature crust is down 15-30cm below treeline and snow is bonding poorly to this layer. The Nov 13 crust is widespread and down 70-120cm. Warmer temps this afternoon will encourage slab development in the upper snowpack.

Avalanche Summary

A report of a close call in Cheops N #6 (Nicci's Notch Couloir) in the Connaught drainage where a size 2.0 avalanche terminated 50m from a group of 2. Skiers also reported skier controlled size 1.5 slabs failing on the the Nov 23 temperature crust on open slopes below treeline. Several natural size 2.0-2.5 were observed in the highway corridor.

Confidence

Problems

Wind Slabs

Strong winds accompanied by new snow have created reactive wind slabs on lee features and in avalanche path start zones. Snow depth above treeline will be variable due to redistribution from wind. Heavily loaded pockets will need time to stabilize.

Be careful with wind loaded pockets, especially near ridge crests and roll-overs.Use caution in lee areas. Recent wind loading have created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Persistent Slabs

Settlement resulting in slab formation over the Nov 13 crust. Field tests on the interface and a stellar layer just above indicate the slab may have a poor bond and may be triggered by light loads. The Nov 23 crust lurks down 30cm below treeline.

Dig down to find and test weak layers before committing to a line.Pay attention to overhead hazards like cornices which could easily trigger the deep persistent slab.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Valid until: Nov 27th, 2016 8:00AM