Avalanche Forecast

Issued: Dec 20th, 2018 4:00PM

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

Deryl Kelly, Parks Canada

Jasper.

Winter is Coming, and the long night approaches! Avalanche Control work will take place on the Icefields Parkway from Parkers Ridge to 12 km north of Sask River Crossing. Road is expected to reopen Friday evening.

Summary

Weather Forecast

Stormy weather is expected overnight Thursday. Could be as much as 20cm of snowfall is forecast to fall thorough to Friday morning. The weekend is expected to be cold, with sunny breaks over the day! A detailed mountain weather forecast is available from Avalanche Canada.

Snowpack Summary

New snow has been blown into fresh wind/storm slabs by moderate SW winds. The Dec 11th persistent weak layer (facets, crust and isolated surface hoar) has been buried by up to 80cm of fallen snow and continues to produce whumfs under foot and sudden results in test profiles. The deep persistent weakness lingers near the ground.

Avalanche Summary

Preparing for another natural avalanche cycle overnight in the Icefields region. Recent explosive work in previously controlled terrain produced a few size 1-1.5 loose snow and slab avalanches. A few large (up to size 3) natural storm and persistent slab avalanches observed after the most recent storm.

Confidence

Problems

Persistent Slabs

This layer now sits under close to a meter of snow, any terrain that has not had previous activity on this layer should be given a wide berth.

Minimize overhead exposure during periods of heavy loading from new snow, wind.Watch for signs of instability such as whumpfing, or cracking.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1.5 - 3.5

Wind Slabs

Moderate SW winds and new snow continues to build fresh wind/storm slabs, particularly near ridge-tops.

The new snow will require several days to settle and stabilize.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

Several recent large avalanches have been the result of the entire snowpack failing on or near the ground due to the weak snowpack structure surrounding this interface.

Be aware of thin areas that may propogate to deeper instabilites.Be aware of the potential for wide propagations.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 3.5

Valid until: Dec 21st, 2018 4:00PM