Avalanche Forecast

Issued: Apr 25th, 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 Loose Dry.

chris gooliaff, Parks Canada

Banff Yoho Kootenay.

Change will be coming to region on Saturday with the passage of a cold front. Winter conditions will prevail through Sunday.

Summary

Weather Forecast

Strong W winds with freezing levels near 2000m are expected through Friday. Saturday will see the passage of a cold front, bringing 10-30cm of snow, along with continued strong W/SW winds. Freezing levels should drop to 1800m with the passage of the front.

Snowpack Summary

Wind slabs can be found in steep alpine features, especially near ridge crests. These slabs can be triggered on all aspects, especially S where they overly harder crusts. A field team up the Storm valley encountered breakable crust to 2350m. They decided to save their legs for days where cooler overnight temp's establish a more supportive crust.

Avalanche Summary

A field team saw a sz 2 cornice triggered avalanche rumble from the ridge-crest near Storm Mountain today. It was likely triggered by a brief, intense sunny period, coupled with strong W winds. There was also evidence of a natural cycle from the last 24-36hrs from all aspects to 2800m in the Storm valley.

Confidence

Forecast snowfall amounts are uncertain

Problems

Wind Slabs

Moderate winds have created areas of thin wind slabs in open areas above 2200 m. These slabs were more sensitive to triggering on southerly aspects where they overly a smooth crust, but are also a concern on northerly aspects.

Ski crampons make travel easier and safer on frozen surface conditionsWatch for areas of hard wind slab in steep alpine features.

Aspects: All aspects.

Elevations: Alpine.

Likelihood

Unlikely - Possible

Expected Size

1 - 2

Loose Dry

Watch for heavy sloughing where powder overlies harder bed surfaces. In steep terrain, this could push you over a cliff or into a terrain trap.

Be cautious of sluffing in steep terrain.

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

Elevations: Alpine.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Apr 26th, 2013 4:00PM