Avalanche Forecast

Issued: Dec 17th, 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.

jonas hoke, Parks Canada

Jasper.

The avalanche danger will spike again over the next couple of days as another series of storms passes our area.Avalanche control is planned between Parkers Ridge and Sask. Crossing on Wednesday Dec. 19th, no ice climbing in the area please.

Summary

Weather Forecast

Unsettled stormy weather through the week as a series of coastal lows bring moisture over the region. Up to 30cm of snowfall is forecast to fall between Monday night and Wednesday morning, with gusting strong westerly winds. A detailed mountain weather forecast is available from Avalanche Canada.

Snowpack Summary

Up to 10cm of new snow is being blown in to fresh wind slabs by moderate SW winds. The December 11th persistent weak layer (facets, crusts and isolated surface hoar) has been buried by up to 70cm of fallen snow - this has been loaded into lee terrain by moderate to strong SW wind. The deep persistent weakness still lingers near the ground.

Avalanche Summary

Large human and explosive triggered avalanches continue to be reported by our neighbors. On Saturday, a field team at Parkers Ridge observed many signs of instability (shooting cracks and whumphs). Last week, a natural avalanche cycle and subsequent avalanche control work resulted in many slab avalanches up to size 3.5 in the Parkers ridge area.

Confidence

Intensity of incoming weather systems is uncertain

Problems

Persistent Slabs

Determining the strength of bond at the Dec11th interface is key to safe travel in avalanche terrain.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1.5 - 3.5

Wind Slabs

Moderate SW winds continue building windslabs particularly at ridge-tops. These were sensitive in lee areas, most notably NE, treeline and alpine features.

Use caution in lee areas. Recent wind loading has created wind slabs.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 the potential for wide propagations.If triggered the wind slabs may step down to deeper layers resulting in large avalanches.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3.5

Valid until: Dec 18th, 2018 4:00PM