Avalanche Forecast

Issued: Dec 25th, 2018 4:00PM

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

Rupert Wedgwood, Parks Canada

Jasper.

Avoid placing yourself under any terrain with cornices overhead as several failures have occurred recently producing large avalanches.

Summary

Weather Forecast

Little change is expected in over the holidays, forecasted winds will remain light and variable as arctic air seeps into the region during the next few days. Temperatures will remain cool as the sun traverses low to the horizon with highs of -10C and overnight lows of -17C. A detailed mountain weather forecast is available from Avalanche Canada.

Snowpack Summary

Last weeks storm snow is providing support underfoot to mountain travelers. Snow conditions at treeline are variable from power, in sheltered areas, to slabs in exposed locations and near ridges. The Dec. 11th persistent weak layer is buried 50-100cm. The deep persistent weakness lingers near the ground in the depth hoar and facets.

Avalanche Summary

Several deep releases from the alpine and been observed in the Icefields area. These avalanches are up to size 3 and appear to have been triggered by cornice failures from South Easterly facing slopes. It is likely these occurred at the interface of last weeks snow and then stepped down to the deep persistent interface at the base of the snowpack.

Confidence

Due to the number of field observations

Problems

Persistent Slabs

The new snow from last week is settling and the interface with the old snow surface, buried up to a meter deep, is strengthening. Large triggers such as cornices have produced several releases in the past 48hrs.

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

Deep Persistent Slabs

The base of the snowpack is weak and facetted. Likely trigger locations are around rocks, where cold air can penetrate to the base of the snowpack, and shallow snowpack locations.

Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Unlikely - Possible

Expected Size

1.5 - 3

Wind Slabs

Winds have abated on all but the highest ridge tops where slabs will be at their most developed.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Avoid open slopes and convex rolls at treeline where buried surface hoar may be preserved.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2.5

Valid until: Dec 26th, 2018 4:00PM