Avalanche Forecast

Issued: Feb 24th, 2017 4:00PM

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

stephen holeczi, Parks Canada

Banff Yoho Kootenay.

Some sporadic natural activity has been seen in the alpine, and human triggered avalanches are still possible. Current conditions are difficult to predict and a wide margin of safety is required.

Summary

Weather Forecast

Highs of -13C Saturday at 2000m and -16C at 3000m with light winds and only trace amounts of snow. Cooler temperatures in the -18 to -20C range for Sunday and Monday with continued light winds.

Snowpack Summary

There is 20-30 cm of low density storm snow (with very little wind effect) at treeline. Common through the area are the weak facets and depth hoar in the lower half of the snowpack, particularly at lower elevations and east of the divide. There is a thin rain-crust below the storm snow at lower elevations.

Avalanche Summary

2 size 2.5 natural avalanches were observed within the last 24 hours. Both were on E-SE aspects in the alpine on Mounts Ball and Brett and both appeared to scrub down to the ground. The trigger was unknown.

Confidence

Due to the number of field observations

Problems

Deep Persistent Slabs

There is a thick slab over a structurally weak snowpack in most areas. Likely areas of triggering are in thin parts of a slope or rocky outcrops at tree line and above. A failure can propagate to deeper areas and cause large avalanches.

Use conservative route selection, choose moderate angled and supported terrain with low consequence.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Feb 25th, 2017 4:00PM