Avalanche Forecast

Issued: Feb 20th, 2013 4:00PM

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

aaron beardmore, Parks Canada

Banff Yoho Kootenay.

Today, explosive control of cornices produced surprisingly large avalanches. Essentially, these large cornices acted like a rake and entrained the loose and faceted snowpack in the avalanche paths affected. Don't forget to look up.

Summary

Weather Forecast

On Friday weather models are showing up to 16cm of precipitation, Additionally, the winds will increase to moderate from the west. This new snow and wind will increase the danger rating to considerable late Friday or early Saturday.

Snowpack Summary

The recent storm snow is starting to settle. On average the storm snow has settled to about 10cm. This storm snow sits on top of wind slabs, both soft and hard, in alpine lee areas.

Avalanche Summary

Avalanche control on Mt. Whymper and Mt. Dennis produced some large 'facet' avalanches. Explosive control was used to drop the cornices above start zones, which subsequently scrapped out the faceted snowpack. However, without a large cornice like scrub brush, avalanches were actually quite hard to trigger.

Confidence

Timing, track, or intensity of incoming weather system is uncertain on Friday

Problems

Wind Slabs

The recent storm snow has started to settle. On average, this amounts to about 10cm. Additionally, wind slabs, both hard and soft, still linger in alpine lee areas.

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

Elevations: Alpine, Treeline.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Cornices

Cornices seem particularly ripe at the moment. Bigger cornices above start zones have the potential to fail and rake out the faceted snowpack, creating large avalanches. Keep in mind what is looming over your head

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 3

Valid until: Feb 21st, 2013 4:00PM