Avalanche Forecast

Issued: Dec 22nd, 2014 5:04PM

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

tim haggarty, Parks Canada

Waterton Lakes.

Significant amounts or recent snow now sits on a weak layer and human triggering is a real possibility. Travel off of trails below about 1900m is still a poor idea. Watch weather forecasts carefully to see exactly what the storm will bring Tuesday.

Summary

Weather Forecast

A system is forecast to approach on Tuesday. West Winds and temperatures will both increase until about midnight and about 10 cm of precip should arrive by midday Wednesday. Models seem to disagree on the intensity of the precip and temperatures from this system but seem to agree on strong winds.

Snowpack Summary

Warm temperatures have kept the coverage thin below 1900m. Up to 170cm of snow now at treeline. 5 to 10cm of Facet Cyrstals capped with isolated pockets of Surface Hoar is sitting on the strong Dec 13 Crust. This weak layer is now buried by 20 to 40cm of Storm Snow at treeline. West Winds have built significant slabs in alpine features

Avalanche Summary

Evidence of a few storms slabs to size 2 could be seen at treeline. Small settlements were also felt by forecasters on patrol near treeline. In alpine areas a few recent slabs could be seen in the lee areas, the North and East aspects, of steep alpine features.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Tuesday

Problems

Storm Slabs

Test the shear found on the weak snow above the crust frequently. Although clean shears found on the facets alone are serious, the isolated areas that hold surface hoar should be treated with even more respect. More snow may make this more touchy.

Dig down to find and test weak layers before committing to a line.Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Wind Slabs

West and South slopes have largely been stripped of snow but expect to find these slabs in the lee areas of exposed features above treeline. Also watch for crossloaded features such as gullies and bear in mind that the small new cornices are weak.

Be cautious as you transition into wind affected terrain.The new snow will require several days to settle and stabilize.

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

Elevations: Alpine.

Likelihood

Likely

Expected Size

1 - 2

Valid until: Dec 25th, 2014 4:00PM