Avalanche Forecast

Issued: Jan 7th, 2015 5:49PM

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

ian jackson, Parks Canada

Banff Yoho Kootenay.

Although natural avalanche activity will taper, avalanche control on Jan. 7th produced size 2 (deep enough to bury a human) or greater avalanches on most if not all shots. Now is the time for caution!

Summary

Weather Forecast

NW flow continues but with a break in the weather systems for Thursday. Expect clearing skies and temperatures falling to between -10 and -15 and falling winds. Friday the temperatures will warm back up again, with the possibility of light precipitation.

Snowpack Summary

Moderate SW winds and warm temperatures today created windslabs at alpine and treeline elevations. These windslabs bond poorly to the Dec 18 layer of facets, crust and some surface hoar down 20-40 cm. At the bottom of the snowpack, the deep peristent basal problem is still a concern and was triggered using explosives today.

Avalanche Summary

Avalanche control in Kootenay and Yoho Park produced between 10-15 avalanches between size 2 and 3. Mostly size 2's with a couple of larger ones. Human triggering is very likely at this time.

Confidence

Due to the number and quality of field observations

Problems

Wind Slabs

Warms temperatures and wind on Jan. 7th have created windslabs that overly the Dec. 18th facet/ surface hoar/ crust layer. Any avalanche triggered on this layer will likely step down to the deep persistent slab layer.

Stick to non-avalanche terrain or small features with limited consequence.Use caution in lee areas. Recent wind loading have created wind slabs.

Aspects: All aspects.

Elevations: Alpine, Treeline.

Likelihood

Likely - Very Likely

Expected Size

1 - 2

Deep Persistent Slabs

The lower part of the snowpack is weak and will be overloaded easily with much additional load. Avoid steep (>35 degree) open slopes at treeline and above. Shallow rocky areas are likely areas to trigger this problem.

If triggered the storm/wind slabs may step down to deeper layers resulting in large avalanches.Be aware of the potential for full depth avalanches due to deeply buried weak layers.

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

2 - 3

Valid until: Jan 8th, 2015 4:00PM