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Avalanche Canada matt.mueller, Avalanche Canada

Kananaskis Country Avalanche Forecast

Feb 22nd, 2019 3:00PM

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

Winds today caused a rapid spike in hazard that will carry over into tomorrow. Re-align your sites for more conservative objectives. Hazard ratings account for avalanches running further than expected.

Summary

Confidence

Moderate - Wind speed and direction is uncertain

Weather Forecast

For most of the night temps will be around -13. In the early morning expect them to drop a few more degrees. Settling at -18 by 8am. UP to 4cm is expected from flurries. Winds...if it wasn't for wind, we'd no weather discussion at all. They should be from the SW tonight, but at midnight they're expected to pull a 180° shift and blow from the NE. If that weren't enough, by noon tomorrow they'll shift to the south. The good news is that they'll be diminishing as these shifts happen.

Avalanche Summary

A big day for avalanches:-numerous loose dry "facalanches". Many seemed cornice triggered and carried surprisingly far; entraining deeper layers as they went. Healthy sz2's. They are more concentrated to the northern part of the region-A group reported a sz2 on the traverse towards the north side of Hero's Knob. Its unknown exactly what triggered it, but it did carry a skier away for a short distance. E aspect at about 2300m.-Numerous thin slabs around the bottoms of large alpine cliffs-Tent Ridge (surprised?) went sz 3 on its eastern aspect mid day today. A cornice triggered a loose dry which in turn triggered the deep persistent layer.

Snowpack Summary

Interesting day today. To sum up the observations, its fair to say the snowpack is changing and the relatively solid snowpack is taking a turn for the worse. The winds picked up last night and instead of changing to a westerly flow, they held a northerly direction and lingered for the better part of today. This made for a rapid reverse loading pattern in the alpine. Lots of spindrift made reactive windslabs around cliffs. Treeline didn't escape the wind either. Slabs are there, but not as thick or dense as higher up. In an untracked, rocky, thin treeline area we had shooting cracks of up to 20m and large settlements. Remoting avalanches suddenly seemed like a real possibility. Open, below treeline areas also had large settlements on the Jan 17 surface hoar. The solar input is strong enough to soften the snow. The warming trend and wind loading is to blame for this rapid decrease in stability.

Problems

Wind Slabs

An icon showing Wind Slabs

Likelihood

Likely

Expected Size

1 - 2
Strong and variable winds today made new slabs. So far they're more prominent at the bottom of cliffs, but expect them to be widespread by Saturday morning.
Avoid travelling in areas that have been reverse loaded by winds.Caution in lee and cross-loaded terrain near ridge crests.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Deep Persistent Slabs

An icon showing Deep Persistent Slabs

Likelihood

Possible - Unlikely

Expected Size

1.5 - 3
More action involving this layer today. It seems the cold has broken down the bridging layer which makes it easier to disturb this layer.
Be aware of the potential for wide propagations due to the presence of hard windslabs.Be aware of the potential for full depth avalanches due to deeply buried weak layers.Be aware of thin areas that may propogate to deeper instabilites.

Aspects:

All aspects.

Elevations:

Alpine, Treeline.

Loose Dry

An icon showing Loose Dry

Likelihood

Possible

Expected Size

1 - 2
These were most prominent in the northern part of the region today. They all ran surprisingly far. They could be a trigger for deeper layers.
Be cautious of sluffing in steep terrain.

Aspects:

North, North East, East, South East, South, South West.

Elevations:

Alpine.

Valid until: Feb 23rd, 2019 2:00PM