Avalanche Forecast

Issued: Feb 14th, 2014 4:10PM

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

Lisa Paulson, Parks Canada

Banff Yoho Kootenay.

Avalanche control planned for tomorrow on Mt. Bourgeau and the Vermillion Crossing (KNP) slide paths. Please no recreational activities in these areas. Extremely touchy conditions in high snow fall areas: KNP, Sunshine back-country, & Yoho.

Summary

Weather Forecast

A break in the snow tomorrow and the wind will be moderate with strong gusts (SW). Another system starting Saturday night through Monday will bring another 10-25 cm, more to the North end of the region. Winds will be strong SW with gusts over 100 kph on Sunday.

Snowpack Summary

Treeline storm snow amounts are 75 cm in Kootenay & Yoho, 60 cm in the Sunshine area, & 25 cm in the Louise/Hwy 93N areas. Winds,warm temps causing slab development in exposed areas,which overlies a complex layer of facets, surface hoar and sun crust on solar aspects. Below this a generally well settled midpack overlying the basal depth hoar layer.

Avalanche Summary

Another field trip to Kootenay, forecasters were able to remote trigger several size 2`s on any steep (>35 deg) unsupported terrain features. One was triggered from 300 m away. These were running 100-300m and were on average 30-40cm deep. One natural size 3 observed on a SE aspect, ran about 1000m. Still touchy around sunshine as well.

Confidence

Due to the quality of field observations

Problems

Persistent Slabs

Touchy slabs continue to build and stiffen over a combination of facets, surface hoar, and sun crust on solar aspects. Large propagations (upto 300 m) and several skier remote triggered avalanches to size 2 were observed today in KNP.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Very Likely

Expected Size

1 - 3

Wind Slabs

Winds will continue to build slabs in the lee of ridge crests and exposed areas. These slabs rest on facets or hard surfaces and have not bonded to these layers yet.

Avoid freshly wind loaded features.Avoid areas with overhead hazard.

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

Elevations: Alpine.

Likelihood

Likely - Very Likely

Expected Size

1 - 3

Deep Persistent Slabs

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

2 - 3

Valid until: Feb 15th, 2014 4:00PM