Avalanche Forecast

Issued: Jan 17th, 2013 4:00PM

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

chris gooliaff, Parks Canada

Banff Yoho Kootenay.

Pay attention to localized wind-loading. Where present, it could be rapidly overloading weak layers. Dig into the snowpack and determine whether you want to commit to steeper features.

Summary

Weather Forecast

Temperatures are forecasted to stay warm over the next couple of days, with freezing levels rising to 1600m. Thankfully the winds should drop to 30-50km/h from the W, which is a welcome change from the honkin' 60-100km/h! We may see a trace of snow tonight/tomorrow. The warmth and the winds remain the key factor to watch.

Snowpack Summary

30 to 50cm of snow sit over the Jan 6th interface. In several locations in Kootenay and some areas near Sunshine, the Jan 6 interface is a well preserved surface hoar (3 to 5mm in size). Tests show easy sudden planar shears. It's worth digging down to it in a few locations to check if it's present. Alpine features have been blasted by recent wind.

Avalanche Summary

During the wind event over the past few days, several size 1.5 - 2 avalanches have been noted in the alpine. One natural triggered size 2 avalanche near Bow Summit in an open wind-effected lee feature at tree-line. We may see continued sporadic small avalanches tomorrow with strong winds forecasted, although most of the snow has been moved already.

Confidence

Problems

Wind Slabs

Recent wind loading have created new wind slabs, predominantly in the alpine. They will certainly be reactive to human loads. A natural size 2 was observed at Bow Summit yesterday. The ensuing strong winds reloaded the slope in a couple of hours.

Avoid freshly wind loaded features.Carry avalanche safety equipment on ice climbs in avalanche terrain.

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

Elevations: Alpine, Treeline.

Likelihood

Likely

Expected Size

1 - 3

Persistent Slabs

Beware of open areas at tree-line and below tree-line. Surface hoar is well preserved in sporadic locations. In wind-loaded areas, it may be buried deeper, creating a thicker slab to avalanche.

Dig down to find and test weak layers before committing to a line.Be cautious as you transition into wind affected terrain.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Possible

Expected Size

2 - 3

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