Avalanche Forecast

Issued: Mar 6th, 2016 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, Wind Slabs and Cornices.

aaron beardmore, Parks Canada

Banff Yoho Kootenay.

Seek supported features without overhead hazard. Today's skier accidental at Bow Summit confirms that large avalanches can be triggered from shallow areas on large terrain features. See discussion.

Summary

Weather Forecast

A cooling trend is expected to start tomorrow along with tapering snowfall amounts. The freezing level is expected to be around the surface. Wind is Westerly and tapering to the light/moderate range towards the end of Monday.

Snowpack Summary

5-10cm of recent storm snow with West wind is forming cohesive slabs in lee areas up to 30cm deep. Discernable layers are difficult to identify below the storm snow, however expect a mix of facets and crusts and in shallow areas depth hoar. In shallow areas snowpack tests results are typically collapses on the ground.

Avalanche Summary

Forecasters received a report of a skier accidental size 2 in the slide path above Peyto Lake, which is accessed from Bow Summit. The party indicated they received numerous whumphs while approaching the slope. They then committed to the slope and the second skier triggered the slide. 15-100cm deep, 30m wide and 300m long. No burials or injuries.

Confidence

Freezing levels are uncertain on Monday

Problems

Deep Persistent Slabs

The mid-pack facets remain weak, especially in thin or rocky areas. Avoid steep or unsupported terrain, and watch for signs of instability such as whumphing and cracking. This weakness will be present for some time.

Minimize exposure to steep, sun exposed slopes when the solar radiation is strong.Be aware of thin areas that may propogate to deeper instabilites.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 3

Wind Slabs

W winds have created small wind slabs in leeward ares near ridge crests. Use common sense to avoid these places, and pay attention to the snow surface conditions while touring - you can usually detect wind slabs easily.

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

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Cornices

Warm temperatures over the weekend combined with moderate west winds and some light precipitation could result in increased cornice failures. Minimize your exposure to cornices.

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

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

1 - 2

Valid until: Mar 7th, 2016 4:00PM