Avalanche Forecast

Issued: Dec 21st, 2018 4:19PM

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

william lawson, Parks Canada

Jasper.

Over 100cm of snow has fallen in the Ice Fields region since Dec 11th. We continue to see wide spread avalanche activity throughout the backcountry. This is the time to be on high alert when traveling in any avalanche terrain.

Summary

Weather Forecast

A cooling trend has taken into affect as the recent storm moved out. Temperatures will gradually warm up through the weekend with alpine highs around -10°c. The sky will be generally a mix of sun and cloud with no precipitation in the near future. Moderate west winds forecasted A detailed mountain weather forecast is available from Avalanche Canada.

Snowpack Summary

Moderate to strong south west winds continue to load lee slopes at tree line and above creating firm windslabs. The Dec. 11th persistent weak layer (facets, crust and isolated surface hoar) has been buried by up to 100cm snow producing sudden results in test profiles. The deep persistent weakness lingers near the ground.

Avalanche Summary

Avalanche control in the Columbia Ice Fields region produced numerous results to size 2.5 triggering both windslabs and persistent slabs at alpine and treeline elevations. A natural avalanche cycle was noted with several large releases to size 3.5. The peak of this natural avalanche cycle seemed to occur during the storm Thursday night.

Confidence

Problems

Persistent Slabs

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

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

Possible - Likely

Expected Size

1.5 - 3.5

Wind Slabs

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

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

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

Elevations: Alpine, Treeline.

Likelihood

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

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1.5 - 3.5

Valid until: Dec 22nd, 2018 4:00PM