Avalanche Forecast

Issued: Feb 19th, 2019 3:10PM

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

jeremy.mackenzie, Alberta Parks

Kananaskis.

Lots of avalanches of different character today (loose dry, wind slabs, deep persistent), and although some were size 2.0, there was generally nothing really big. Conservative terrain choices will help avoid these problems.

Summary

Confidence

High -

Weather Forecast

Wednesday will be mostly cloudy with light flurries. Winds will be light to moderate from the NE and temperatures should climb to -9 by the afternoon. Very light flurries expected Thursday and Friday.

Avalanche Summary

Recent strong winds resulted in several loose dry avalanches up to size 2.0, primarily in very steep Alpine terrain on all aspects. In addition, the deep persistent layer of basal facets finally woke up and a size 2.0 naturally triggered slab occurred on the north end of Tent Bowl around midday today. This slide occurred at Treeline and was only about 40m wide, but was between 120 and 140cm deep and failed on the basal facets. Avalanche control today on EEOR resulted in another full depth avalanche that deposited large amounts of debris on HWY 742.

Snowpack Summary

Alpine and Treeline areas suffered some wind damage in the past 24 hours, and there are now fresh wind slabs in some of this terrain. Typical lee and cross-loaded features will have wind slabs, but reverse wind-loading can also be expected due to recent N and NW winds. The late February sun is now powerful enough to create sun crusts on some steep solar aspects, but cold temperatures have been reducing this somewhat. The mid pack has enough strength and depth (in most places) that triggering the bottom layers is becoming more difficult. The key to avoiding trouble is avoiding thin areas where the bridging is minimal.

Problems

Wind Slabs

Strong winds last night led to wind slab development in the Alpine and just into Treeline. Watch for reverse loading due to northerly winds.

Caution in lee and cross-loaded terrain near ridge crests.Avoid travelling in areas that have been reverse loaded by winds.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Loose Dry

Several loose dry avalanches from very steep terrain in the past 24hrs. Be mindful of what's above you.

Avoid travelling under cliffs that are exposed to sluffing from above.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Deep Persistent Slabs

The basal facets finally woke up today. Some time around midday a full depth avalanche occurred at Treeline on Tent Ridge. This layer is still unlikely to trigger, but has severe consequences if it does fail.

Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2.5

Valid until: Feb 20th, 2019 2:00PM