Avalanche Forecast

Issued: Jan 14th, 2019 4:45PM

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

tim haggarty, Parks Canada

Banff Yoho Kootenay.

Another day of temperature inversions and solar heating will keep slabs sensitive to failure on Tuesday.

Summary

Weather Forecast

Continued warm temperatures and sun are expected Tuesday as the temperature inversion continues .Â Winds that have been in the moderate range out of the West are forecast to diminish through to Wednesday.Â Cooling is expected on Wednesday increasing cloud. Trace amounts of snow can be expected Thursday.

Snowpack Summary

New solar crusts steep South and West slopes. Extensive wind effect in the alpine, less so at treeline. In thick snowpack areas, the Dec 10th weak layer of facets is now down 100-150cm with a stronger snowpack below. In thin snowpack areas, there is little separation between Dec 10 and the weak depth hoar/ facets sitting 40 cm above the ground.

Avalanche Summary

A size 3 slab failed on the south aspect of Mt Fairview sometime during the last couple days of temperature inversions and clear skies. The crown was 70cm to 1m deep and over 1000m wide. The slide ran up the other side of the valley below Sheol. There were 2 sz 2 loose wet avalanches observed on a field trip to Hamilton Lake at 2400m west aspect.

Confidence

Problems

Deep Persistent Slabs

The weak facets and depth hoar just above the ground have an significant slab sitting above them . It is difficult to travel with any confidence given this structure. Some large natural avalanches are still occurring and human triggering is likely.

Be aware of the potential for wide propagations which could result in large avalanches.Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

2 - 3.5

Wind Slabs

These wind slabs are becoming older and are likely less reactive but should be treated with respect especially while the warm conditions continue. If initiated these slabs could provide enough load to trigger the deeper basal layers.

Use caution in lee and cross-loaded terrain near ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Jan 15th, 2019 4:00PM