Avalanche Forecast

Issued: Nov 29th, 2017 3:15PM

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

KESAdmin, Alberta Parks

Kananaskis.

Thin areas in the Alpine and at treeline are where you may be able to trigger the persistent slab. Watch for new windslabs building overnight.

Summary

Confidence

High -

Weather Forecast

Trace amounts of snow are forecast over the next 24hrs. Temps will be cooler in the -12C range and winds will continue to be strong at Alpine elevations. Later in the week we may see a few more cm of snow up to 10cm.

Avalanche Summary

Only one new slab was observed near Mt Lawson, on a NE aspect at 2700m. The start zone was obscured but it was a sz 2.5 that ran down and into treeline.

Snowpack Summary

5-14cm of snow over the past 24hrs with moderate alpine westerly winds is continuing to build windslabs in alpine areas. Field teams on Wednesday in the Highwood pass area found these slabs 20-30cm thick but they were stubborn to trigger. Places where we have the most concern for this problem is along ridgelines in immediate lee, cross loaded gullies. The snow pack is currently fairly complex. The Nov 26th crust is being found up to 2450m (30cm down), the Nov 23rd crust (down 50cm) up to 2600m and the Halloween crust up to 2600m (down 100cm at treeline). Hard result were observed in a weak facet layer below the Halloween crust. Avoid thin areas where you may trigger this weakness.

Problems

Wind Slabs

Expect windslab development in lee and cross loaded gullies. These problems are easy to locate in the alpine and more specific in treeline areas.

Watch for areas of hard wind slab in steep alpine features.Avoid freshly wind loaded features.Use caution in lee areas. Recent wind loading has created wind slabs.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

The new crusts are preventing the deeper layers from disturbance. Remember, in shallow areas it is still possible to trigger the deeper layers.

Be cautious in shallow snowpack areas where triggering is more likely.Be aware of the potential for wide propagations.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Nov 30th, 2017 2:00PM