Avalanche Forecast

Issued: Jan 23rd, 2016 4:52PM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is low. Known problems include Wind Slabs, Loose Dry and Storm Slabs.

tim haggarty, Parks Canada

Banff Yoho Kootenay.

A significant avalanche cycle and results from explosive testing confirm that we have left the days of triple low behind us. Climbers and skiers need to take a conservative approach to terrain selection as we come out of this period of change.

Summary

Weather Forecast

A return to cloudy skies this afternoon promises to bring about 5 cm of snow with light west winds. Temperatures will return to -10C values at valley bottom for the period with mainly cloudy skies and possibly a few flurries.

Snowpack Summary

Strong S and SW winds with up to 10 cm of snow Friday produced soft slabs at Alpine and Treeline elevations as well as fragile cornice growth . Below treeline rain fell up to 2000m. There is now 20 to 25 cm over weak faceted snow in the upper snowpack and while the mid and lower pack are supportive in thick areas, thin areas are faceted out.

Avalanche Summary

Following the storm Friday a natural avalanche cycle resulting from the strong SW winds was evident today. Explosive control in Yoho today confirms that soft slabs can be triggered 20 to 40 cm deep in the alpine and treeline to size 2.5 and that loose dry avalanches continue to run a surprising distance at all elevations up to size 2.

Confidence

Problems

Wind Slabs

Many ridgecrest features have been loaded by S and SW winds with the recent storm and new cornice growth is evident. Soft slabs may become buried by incoming snow tonight and may not appear obvious.

Avoid lee and cross-loaded terrain near ridge crests.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 2

Loose Dry

The new surface snow and underlying sugary facets continue to produce impressive sluff avalanches that run a surprising distance in steep terrain. Avoid large or confined terrain features where these events can gather mass and speed.

Good group management is essential to manage current conditions safely.On steep slopes, pull over periodically or cut into a new line to manage sluffing.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Likely

Expected Size

1 - 2

Storm Slabs

The snow that has slowly accumulated over the older sugary facets is starting to form a slab. Use hand tests to evaluate the bond at this interface found 20 to 25 cm deep and be cautious in areas where a dense slab has formed.

Watch for signs of instability such as whumpfing, or cracking.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Jan 24th, 2016 4:00PM