Avalanche Forecast

Issued: Dec 15th, 2018 4:00PM

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

deryl kelly, Parks Canada

Jasper.

We have a very complicated snowpack that will require a careful and conservative assessment before committing to any avalanche terrain. Ice climbs with significant overhead hazard should be avoided until the hazard abates.

Summary

Weather Forecast

Low approaching from the Coast. Building cloud, increasing SW winds and light precipitation for Sunday afternoon, with further snowfall and mild temperatures continuing into the week.A detailed mountain weather forecast is available from Avalanche Canada.

Snowpack Summary

60cm of new snow has fallen since Dec. 11th in the Icefields, south to Rampart Creek areas (much less to the north), and has been redistributed by moderate SW wind. The resulting storm and wind slabs overly several weak interfaces - facets, crusts and isolated surface hoar. A deep persistent weaknesses still lingers in the bottom of the snowpack.

Avalanche Summary

A natural avalanche cycle triggered by this weeks storm resulted in numerous storm and wind slab avalanches up to size 3.5. Avalanche control work in the Parkers ridge area on Friday (Dec. 14th) produced numerous slab avalanches up to size 2.5 - direct evidence that despite natural triggering having slowed, human triggering remains likely.

Confidence

Problems

Wind Slabs

Moderate winds, perfect for slab production has been observed at all elevations. Noticeably sensitive lee areas observed on NE, alpine aspects.

Use caution in lee areas. Recent wind loading has created wind slabs.Minimize overhead exposure during periods of heavy loading from wind.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1.5 - 3

Storm Slabs

The new snow will continue to settle over time. Determining the strength of bond at the Dec. 11 interface will be key to safe travel in open features at treeline and below.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.The new snow will require several days to settle and stabilize.

Aspects: All aspects.

Elevations: Treeline, Below Treeline.

Likelihood

Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

Normally found 20-30cm off the ground. Potential for step-down avalanches if you trigger a wind slab or storm slab.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3.5

Valid until: Dec 16th, 2018 4:00PM