Avalanche Forecast

Issued: Mar 14th, 2014 4:00PM

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

stephen holeczi, Parks Canada

Banff Yoho Kootenay.

Expect the avalanche danger to increase this weekend. Slopes with a thin and variable snowpack will be the most susceptible to human triggering. SH

Summary

Weather Forecast

Strong to Extreme Westerly winds in the alpine starting Friday evening through to the end of the weekend. A system will enter the region on Saturday afternoon with current forecasts calling for roughly 25-40cm by Monday. Alpine temperatures will stay in -8 to -12 C range, and freezing levels will be at valley bottom.

Snowpack Summary

West winds have created widespread wind effect in the ALP and at TL.Â Below 1500m a rain crust exists. The Feb.10th layer is down 50-110 and is reactive with large whumphs and sudden collapse results in thin snowpack areas, and hard results observed in thick snowpack areas.Â

Avalanche Summary

No new avalanche activity noted today. Yesterday there was still extensive whumpfing on Helen Shoulder which was a thin snowpack with a buried sun crust (E side of divide). We are still only just coming out of a major avalanche cycle.

Confidence

Forecast snowfall amounts are uncertain on Sunday

Problems

Persistent Slabs

This layer is still touchy in thin snowpack areas (especially where there is a buried sun crust), and large whumps and sudden collapse results have been found. With limited observations this layer now seems less reactive in deeper snowpack areas.

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

Likely

Expected Size

2 - 3

Wind Slabs

Lee slopes will be loaded from recent strong westerly winds. With more wind and snow in the forecast, these wind slabs will increase in likelihood and size through the weekend.

If triggered the wind slabs may step down to deeper layers resulting in large avalanches.Use caution in lee areas. Recent wind loading have created wind slabs.

Aspects: North, North East, East.

Elevations: Alpine, Treeline.

Likelihood

Possible - Likely

Expected Size

1 - 2

Valid until: Mar 15th, 2014 4:00PM