Avalanche Forecast

Issued: Mar 17th, 2013 6:12PM

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

snow safety, Parks Canada

Banff Yoho Kootenay.

The new storm snow today has added to the touchy avalanche conditions at and above treeline. Conservative terrain choice is still required. Below treeline the colder temps will freeze the wet snow and lower the danger.

Summary

Weather Forecast

A short lived ridge Tuesday will be followed by a progressive pattern with some precipitation, strong westerliesÂ and moderate temps

Snowpack Summary

Another 10-35cm of storm snow fell with the passing of the arctic air bringing the total this week to near 60 in most alpine areas. Large cornices and storm slabs exist at treeline and above with touchy slabs. Below treeline, the rain line was at nearly 2000 metres, and the snow is still wet below a weak crust that will freeze with cold temps.

Avalanche Summary

A widespread avalanche cycle has been occurring over the last few days. Slabs have been observed to size three failing both with cornice fall, wind and wet conditions. Avalanche control today produced some deep slabs and large cornice falls with several size three avalanches with crowns over 1M thick.

Confidence

Timing or intensity of solar radiation is uncertain on Tuesday

Problems

Storm Slabs

Recent storm snow has created a touchy slab condition in all open areas. Easy triggering of slabs is expected.

Use careful route-finding and stick to moderate slope angles with low consequencesChoose conservative lines and watch for clues of instability.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Cornices

Cornices are very large and unstable due to recent loading and high humidity. Natural and human triggering is likely

Do not travel on slopes that are exposed to cornices overhead.Give cornices a wide berth when travelling on or below ridges.

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

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Mar 18th, 2013 4:00PM