Avalanche Forecast

Issued: Nov 15th, 2012 4:00PM

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

chris gooliaff, Parks Canada

Banff Yoho Kootenay.

A warm and windy storm may blow through on the weekend, but expect little change in the danger levels until it arrives Saturday afternoon.

Summary

Weather Forecast

Little change in the weather on Friday, but expect ridge-top winds to pick up to strong/extreme from the W/SW on Saturday, with freezing levels spiking to 1800m and 5-10cm Saturday night.

Snowpack Summary

A field trip to the Bow Summit area today found an average snowpack of 55-65cm. Generally, 20-25cm of variable soft slabs with pockets of unconsolidated snow overlay the laminated November rain crust, which supported skis but not a person on foot.

Avalanche Summary

No new activity seen in the last 48 hours. Expect a natural cycle to develop on Saturday, especially later in the day, when warm temperatures, strong winds, and new snow combine to create windslabs.

Confidence

Forecast snowfall amounts are uncertain

Problems

Wind Slabs

Various hard and soft wind slabs (20-50cm thick) in the alpine are sitting on the Nov 6 crust and producing moderate/hard shears in compression tests. Slabs are stubborn but still possible for a skier to trigger these in steep lee terrain.

Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Persistent Slabs

Deep slabs size 2-3 have been noted on isolated steep alpine slopes over the past week. Failure plane was at the bottom of the snow pack on firn or glacier ice.�No new have been reported these last few days but are still possible in the high alpine.

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

Aspects: North, North East, East.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Nov 16th, 2012 4:00PM