Avalanche Forecast

Issued: Feb 16th, 2017 6:03PM

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

brian webster, Parks Canada

Banff Yoho Kootenay.

Potential for large avalanches persist. Conservative route choices remain the theme of the day. Iceclimbers should pay attention to freezing levels and adjust there route choices accordingly.

Summary

Weather Forecast

Friday will be mainly cloudy with some isolated flurries. Freezing levels will be around 1300m and the winds will be moderate from the west. There will be a continued cooling trend for Saturday.

Snowpack Summary

10-20 cm of fresh snow (at treeline) and up to 50 cm of storm snow in the past week have formed a cohesive slab overtop of a series of weak layers. Test results show sudden shear failures on these layers. Moderate SW winds have created fresh wind slabs on lee aspects at treeline and above. Below 1800 m the snowpack is moist from rain event on Thur.

Avalanche Summary

A series of loose wet avalanches triggered by warm weather and rain were observed at lower elevations on Thursday. Skihills reported several smaller windslab avalanches near ridgetops. A Skier triggered a size 2.5 avalanche on Lipalian 2 (west aspect) outside Lake Louise ski area occurred on Wednesday.

Confidence

Problems

Wind Slabs

Fresh snow and moderate SW winds have created touchy windslabs in alpine and open terrain near treeline.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Deep Persistent Slabs

The recent storm snow has created a touchy slab over the weak faceted midpack at all elevations. Avalanches could run full path. Extra caution is warranted until the snowpack has adjusted to this extra load.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 4

Loose Wet

Loose wet avalanches were observed on Thursday below 1900m. Despite cooler temperatures forecast for Friday this still may be a problem at lower elevations. Pay attention to day-time temperatures.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Feb 17th, 2017 4:00PM