Avalanche Forecast

Issued: Jan 2nd, 2019 4:00PM

The alpine rating is high, the treeline rating is high, and the below treeline rating is high. Known problems include Storm Slabs, Deep Persistent Slabs and Loose Dry.

ian jackson, Parks Canada

Banff Yoho Kootenay.

A major storm is starting Wednesday night. It is a good time to ski at the resorts and stay out of avalanche terrain.

Summary

Weather Forecast

A major system is heading for the forecast region starting tonight. The models have varying data but upwards of 40cm is expected throughout Thursday and Friday. The system is accompanied by warm temperatures and moderate to strong westerly winds = a perfect recipe for avalanches!

Snowpack Summary

Wind effect exists in the alpine and at treeline. Below treeline, the surface is faceted powder. This overlies the Dec. 10th layer of facets and depth hoar which is down 60-100 cm. In thin snowpack areas, the Dec. 10th layer is mixed in with the basal facets and October crust. In thicker areas, it is a distinct layer, with a stronger snowpack below

Avalanche Summary

Two skiier accidentals and a skiier remote avalanche

were reported by the public in the Banff, Yoho & Kootenay forecast region yesterday. They were all size 1.5-2 and all failed in thin snowpack areas. Two were in the alpine and one was below treeline in a steep gully feature. Avalanche control on Mt Field today produced avalanches up to size 3

Confidence

Intensity of incoming weather systems is uncertain

Problems

Storm Slabs

Forecasts are calling for ~25 cm's by the morning and up to 50 cm's by Thursday evening. This will certainly form a touchy slab. Any avalanches initiated here are likely to step down to the deeper Dec. 10th layer.

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

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely - Very Likely

Expected Size

1 - 2.5

Deep Persistent Slabs

The 60-100 cm slab overlying the Dec. 10th layer of facets and surface hoar will become overloaded with the forecasted 30-50 cm of snow on Thursday. Any avalanche that initiates is highly likely to step down to this layer.

Be aware of the potential for wide propagations which could result in large avalanches.Avoid all avalanche terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1.5 - 3

Loose Dry

25-50 cm of new snow on Thursday will sluff easily and is very likely to initiate a larger avalanche on the Persistent slab layer

Be very cautious with gully features.Avoid all avalanche terrain.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Very Likely

Expected Size

1 - 2

Valid until: Jan 3rd, 2019 4:00PM